battery imformation

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Battery Tutorial If you have done any research on how batteries work or what you should look for when selecting a battery, you are probably buried in information, some of which is conflicting. At BatteryStuff, we aim to clear that up a bit.You have most likely heard the term K.I.S.S. (Keep It Simple, Stupid). I am going to attempt to explain how lead acid batteries work and what they need without burying you with a bunch of needless technical data. I have found that battery data will vary somewhat from manufacturer to manufacturer, so I will do my best to boil that data down. This means I may generalize a bit, while staying true to purpose. The commercial use of the lead acid battery is over 100 years old. The same chemical principal that is being used to store energy is basicly the same as our Great Grandparents may have used. If you can grasp the basics you will have fewer battery problems and will gain greater battery performance, reliability, and longevity. I suggest you read the entire tutorial, however I have indexed all the information for a quick read and easy reference. A battery is like a piggy bank. If you keep taking out and putting nothing back you soon will have nothing. Present day chassis battery power requirements are huge. Consider today’s vehicle and all the electrical devices that must be supplied. All these electronics require a source of reliable power, and poor battery condition can cause expensive electronic component failure. Did you know that the average auto has 11 pounds of wire in the electrical system? Look at RVs and boats with all the electrical gadgets that require power. It was not long ago when trailers or motor homes had only a single 12-volt house battery. Today it is standard to have two or more house batteries powering inverters up to

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Page 1: Battery Imformation

Battery TutorialIf you have done any research on how batteries work or what you should look for when selecting a battery, you are probably buried in information, some of which is conflicting. At BatteryStuff, we aim to clear that up a bit.You have most likely heard the term K.I.S.S. (Keep It Simple, Stupid). I am going to attempt to explain how lead acid batteries work and what they need without burying you with a bunch of needless technical data. I have found that battery data will vary somewhat from manufacturer to manufacturer, so I will do my best to boil that data down. This means I may generalize a bit, while staying true to purpose.

The commercial use of the lead acid battery is over 100 years old. The same chemical principal that is being used to store energy is basicly the same as our Great Grandparents may have used.

If you can grasp the basics you will have fewer battery problems and will gain greater battery performance, reliability, and longevity. I suggest you read the entire tutorial, however I have indexed all the information for a quick read and easy reference.

A battery is like a piggy bank. If you keep taking out and putting nothing back you soon will have nothing. Present day chassis battery power requirements are huge. Consider today’s vehicle and all the electrical devices that must be supplied. All these electronics require a source of reliable power, and poor battery condition can cause expensive electronic component failure. Did you know that the average auto has 11 pounds of wire in the electrical system? Look at RVs and boats with all the electrical gadgets that require power. It was not long ago when trailers or motor homes had only a single 12-volt house battery. Today it is standard to have two or more house batteries powering inverters up to 4000 watts.

Average battery life has become shorter as energy requirements have increased. Life span depends on usage; 6 months to 48 months, yet only 30% of all batteries actually reach the 48-month mark.

A Few Basics

The Lead Acid battery is made up of plates, lead, and lead oxide (various other elements are used to change density, hardness, porosity, etc.) with a 35% sulfuric acid and 65% water solution. This solution is called electrolyte, which causes a chemical reaction that produce electrons. When you test a battery with a hydrometer, you are measuring the amount of sulfuric acid in the electrolyte. If your reading is low, that means the chemistry that makes electrons is lacking. So where did the sulfur go? It is resting on the battery plates and when you recharge the battery, the sulfur returns to the electrolyte.

1. Safety 2. Battery types, Deep Cycle and Starting 3. Wet Cell, Gel-Cell and Absorbed Glass Mat (AGM)

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4. CCA, CA, AH and RC; what's that all about? 5. Battery Maintenance 6. Battery Testing 7. Selecting and Buying a New Battery 8. Battery Life and Performance 9. Battery Charging 10. Battery Do's 11. Battery Don'ts

1. We must think safety when we are working around and with batteries. Remove all jewelry. After all you don't want to melt your watchband while you are wearing the watch. The hydrogen gas that batteries make when charging is very explosive. We have seen several instances of batteries blowing up and drenching everything in sulfuric acid. That is no fun, and would have been a good time to use those safety goggles that are hanging on the wall. Heck, just break out your disco outfit. Polyester is not affected by Sulfuric Acid, but anything with cotton will be eaten up. If you do not feel the need to make a fashion statement just wear junk clothes, after all Polyester is still out of style. When doing electrical work on vehicles it is best to disconnect the ground cable. Just remember you are messing with corrosive acid, explosive gases and 100's amps of electrical current.

2. Basically there are two types of lead acid batteries (along with 3 sub categories); The two main types are Starting (cranking), and Deep Cycle (marine/golf cart). The starting battery (SLI starting lights ignition) is designed to deliver quick bursts of energy (such as starting engines) and therefore has a greater plate count. The plates are thinner and have somewhat different material composition. The deep cycle battery has less instant energy, but greater long-term energy delivery. Deep cycle batteries have thicker plates and can survive a number of discharge cycles. Starting batteries should not be used for deep cycle applications because the thinner plates are more prone to warping and pitting when discharged. The so-called Dual Purpose Battery is a compromise between the two types of batteries, though it is better to be more specific if possible.

3. Wet Cell (flooded), Gel Cell, and Absorbed Glass Mat (AGM) are various versions of the lead acid battery. The Wet cell comes in two styles; Serviceable and Maintenance free. Both are filled with electrolyte and are basicly the same. I prefer one that I can add water to and check the specific gravity of the electrolyte with a hydrometer. The Gel Cell and the AGM batteries are specialty batteries that typically cost twice as much as a premium wet cell. However they store very well and do not tend to sulfate or degrade as easily as wet cell. There is little chance of a hydrogen gas explosion or corrosion when using these batteries; these are the safest lead acid batteries you can use. Gel Cell and some AGM batteries may require a special charging rate. If you want the best,most versatile type, consideration should be given to the AGM battery for applications such as Marine, RV, Solar, Audio, Power Sports and Stand-By Power just to name a few. If you don't use or operate your equipment daily, AGM batteries will hold their charge better that other types. If you must depend on top-notch battery performance, spend the extra

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money. Gel Cell batteries still are being sold but AGM batteries are replacing them in most applications. There is a some common confusion regarding AGM batteries because different manufactures call them by different names; some of the more common names are "sealed regulated valve", "dry cell", "non spillable", and "Valve Regulated Lead Acid" batteries. In most cases AGM batteries will give greater life span and greater cycle life than a wet cell battery. SPECIAL NOTE about Gel Batteries: It is very common for individuals to use the term GEL CELL when referring to sealed, maintenance free batteries, much like one would use Kleenex when referring to facial tissue or "Xerox machine" when referring to a copy machine. Be very careful when specifying a battery charger, many times we are told by customer they are requiring a charger for a Gel Cell battery and in fact the battery is not a Gel Cell.

AGM: The Absorbed Glass Matt construction allows the electrolyte to be suspended in close proximity with the plates active material. In theory, this enhances both the discharge and recharge efficiency. Common manufacturer applications include high performance engine starting, power sports, deep cycle, solar and storage battery. The larger AGM batteries we sell are typically good deep cycle batteries and they deliver their best life performance if recharged before allowed to drop below the 50% discharge rate. The Scorpion motorcycle batteries we carry are a nice upgrade from your stock flooded battery, and the Odyssey branded batteries are fantastic for holding their static charge over long periods of non use. When Deep Cycle AGM batteries are discharged to a rate of no less than 60% the cycle life will be 300 plus cycles.

GEL: The Gel Cell is similar to the AGM style because the electrolyte is suspended, but different because technically the AGM battery is still considered to be a wet cell. The electrolyte in a Gel Cell has a silica additive that causes it to set up or stiffen. The recharge voltage on this type of cell is lower than the other styles of lead acid battery. This is probably the most sensitive cell in terms of adverse reactions to over-voltage charging. Gel Batteries are best used in VERY DEEP cycle application and may last a bit longer in hot weather applications. If the incorrect battery charger is used on a Gel Cell battery poor performance and premature failure is certain.

4. CCA, CA, AH and RC. What are these all about? These are the standards that most battery companies use to rate the output and capacity of a battery.

Cold cranking amps (CCA) is a measurement of the number of amps a battery can deliver at 0 ° F for 30 seconds and not drop below 7.2 volts. So a high CCA battery rating is especially important in starting battery applications, and in cold weather.This measurement is not particularly important in Deep cycle batteries, though it is the most commonly 'known' battery measurement.

CA is cranking amps measured at 32 degrees F. This rating is also called marine cranking amps (MCA). Hot cranking amps (HCA) is seldom used any longer but is measured at 80 ° F.

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Reserve Capacity (RC) is a very important rating. This is the number of minutes a fully charged battery at 80 ° F will discharge 25 amps until the battery drops below 10.5 volts.

An amp hour (AH) is a rating usually found on deep cycle batteries. If a battery is rated at 100 amp hours it should deliver 5 amps for 20 hours, 20 amps for 5 hours, etc.

5. Battery Maintenance is an important issue. The battery should be cleaned using a baking soda and water solution; a couple of table spoons to a pint of water. Cable connections need to be cleaned and tightened as battery problems are often caused by dirty and loose connections. A serviceable battery needs to have the fluid level checked. Use only mineral free water, Distilled is best as all impurities have been removed, and there is nothing left that could contaminate your cells. Don't overfill battery cells especially in warmer weather because the natural fluid expansion in hot weather can push excess electrolytes from the battery. To prevent corrosion of cables on top post batteries use a small bead of silicon sealer at the base of the post and place a felt battery washer over it. Coat the washer with high temperature grease or petroleum jelly (Vaseline), then place cable on the post and tighten. Coat the exposed cable end with the grease. Most folks don't know that just the gases from the battery condensing on metal parts cause most corrosion.

6. Battery Testing can be done in more than one way. The most accurate method is measurement of specific gravity and battery voltage. To measure specific gravity buy a temperature compensating hydrometer, to measure voltage use a digital D.C. Voltmeter. A quality load tester may be a good purchase if you need to test sealed batteries.

For any of these methods, you must first fully charge the battery and then remove the surface charge. If the battery has been sitting at least several hours (I prefer at least 12 hours) you may begin testing. To remove surface charge the battery must be discharged for several minutes. Using a headlight (high beam) will do the trick. After turning off the light you are ready to test the battery.

State of Charge Specific Gravity Voltage

12V 6V

100% 1.265 12.7 6.3

*75% 1.225 12.4 6.2

50% 1.190 12.2 6.1

25% 1.155 12.0 6.0

Discharged 1.120 11.9 6.0

*Sulfation of Batteries starts when specific gravity falls below 1.225 or voltage measures less than 12.4 for a 12v battery, or 6.2 for a 6 volt battery. Sulfation hardens on the

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battery plates reducing and eventually destroying the ability of the battery to generate Volts and Amps.

Load testing is yet another way of testing a battery. Load test removes amps from a battery much like starting an engine would. A load tester can be purchased at most auto parts stores. Some battery companies label their battery with the amp load for testing. This number is usually 1/2 of the CCA rating. For instance, a 500CCA battery would load test at 250 amps for 15 seconds. A load test can only be performed if the battery is near or at full charge.

The results of your testing should be as follows:

Hydrometer readings should not vary more than .05 differences between cells.

Digital Voltmeters should read as the voltage is shown in this document. The sealed AGM and Gel-Cell battery voltage (full charged) will be slightly higher in the 12.8 to 12.9 ranges. If you have voltage readings in the 10.5 volts range on a charged battery, that typically indicates a shorted cell.

If you have a maintenance free wet cell, the only ways to test are voltmeter and load test. Any of the maintenance free type batteries that have a built in hydrometer(black/green window) will tell you the condition of 1 cell of 6. You may get a good reading from 1 cell but have a problem with other cells in the battery.

When in doubt about battery testing, call the battery manufacturer. Many batteries sold today have a toll free number to call for help.

7. Selecting a Battery - When buying a new battery I suggest you purchase a battery with the greatest reserve capacity or amp hour rating possible. Of course the physical size, cable hook up, and terminal type must be a consideration. You may want to consider a Gel Cell or an Absorbed Glass Mat (AGM) rather than a Wet Cell if the application is in a harsher environment or the battery is not going to receive regular maintenance and charging.

Be sure to purchase the correct type of battery for the job it must do. Remember that engine starting batteries and deep cycle batteries are different. Freshness of a new battery is very important. The longer a battery sits and is not re-charged the more damaging sulfation build up there may be on the plates. Most batteries have a date of manufacture code on them. The month is indicated by a letter 'A' being January and a number '4' being 2004. C4 would tell us the battery was manufactured in March 2004. Remember the fresher the better. The letter "i" is not used because it can be confused with #1.

Battery warranties are figured in the favor of battery manufactures. Let's say you buy a 60-month warranty battery and it lives 41 months. The warranty is pro-rated so when taking the months used against the full retail price of the battery you end up paying about the same money as if you purchased the battery at the sale price. This makes the

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manufacturer happy. What makes me happy is to exceed the warranty. Let me assure you it can be done.

8. Battery life and performance - Average battery life has become shorter as energy requirements have increased. Two phrases I hear most often are "my battery won't take a charge, and my battery won't hold a charge". Only 30% of batteries sold today reach the 48-month mark. In fact 80% of all battery failure is related to sulfation build-up. This build up occurs when the sulfur molecules in the electrolyte (battery acid) become so deeply discharged that they begin to coat the battery's lead plates. Before long the plates become so coated that the battery dies. The causes of sulfation are numerous. Let me list some for you.

Batteries sit too long between charges. As little as 24 hours in hot weather and several days in cooler weather.

Battery is stored without some type of energy input. "Deep cycling" an engine starting battery. Remember these batteries can't stand

deep discharge. Undercharging of a battery to only 90% of capacity will allow sulfation of the

battery using the 10% of battery chemistry not reactivated by the incompleted charging cycle.

Heat of 100 plus F., increases internal discharge. As temperatures increase so does internal discharge. A new fully charged battery left sitting 24 hours a day at 110 degrees F for 30 days would most likely not start an engine.

Low electrolyte level - battery plates exposed to air will immediately sulfate. Incorrect charging levels and settings. Most cheap battery chargers can do more

harm than good. See the section on battery charging. Cold weather is also hard on the battery. The chemistry does not make the same

amount of energy as a warm battery. A deeply discharged battery can freeze solid in sub zero weather.

Parasitic drain is a load put on a battery with the key off. More info on parasitic drain will follow in this document.

There are ways to greatly increase battery life and performance. All the products we sell are targeted to improve performance and battery life.

An example: Let's say you have "toys"; an ATV, classic car, antique car, boat, Harley, etc. You most likely don't use these toys 365 days a year as you do your car. Many of these toys are seasonal so they are stored. What happens to the batteries? Most batteries that supply energy to power our toys only last 2 seasons. You must keep these batteries from sulfating or buy new ones. We sell products to prevent and reverse sulfation. The PulseTech products are patented electronic devices that reverse and prevent sulfation. Also Battery Equaliser, a chemical battery additive, has proven itself very effective in improving battery life and performance. Other devices such as Solar Trickle Chargers are a great option for battery maintenance.

Parasitic drain is a load put on a battery with the key off. Most vehicles have clocks,

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engine management computers, alarm systems, etc. In the case of a boat you may have an automatic bilge pump, radio, GPS, etc. These devices may all be operating without the engine running. You may have parasitic loads caused by a short in the electrical system. If you are always having dead battery problems most likely the parasitic drain is excessive. The constant low or dead battery caused by excessive parasitic energy drain will dramatically shorten battery life. If this is a problem you are having, check out the Priority Start and Marine Priority Start to prevent dead batteries before they happen. This special computer switch will turn off your engine start battery before all the starting energy is drained. This technology will prevent you from deep cycling your starting battery.

9. Battery Charging - Remember you must put back the energy you use immediately. If you don't the battery sulfates and that affects performance and longevity. The alternator is a battery charger. It works well if the battery is not deeply discharged. The alternator tends to overcharge batteries that are very low and the overcharge can damage batteries. In fact an engine starting battery on average has only about 10 deep cycles available when recharged by an alternator. Batteries like to be charged in a certain way, especially when they have been deeply discharged. This type of charging is called 3 step regulated charging. Please note that only special SMART CHARGERS using computer technology can perform 3 step charging techniques. You don't find these types of chargers in parts stores and Wal-Marts. The first step is bulk charging where up to 80% of the battery energy capacity is replaced by the charger at the maximum voltage and current amp rating of the charger. When the battery voltage reaches 14.4 volts this begins the absorption charge step. This is where the voltage is held at a constant 14.4 volts and the current (amps) declines until the battery is 98% charged. Next comes the Float Step. This is a regulated voltage of not more than 13.4 volts and usually less than 1 amp of current. This in time will bring the battery to 100% charged or close to it. The float charge will not boil or heat batteries but will maintain the batteries at 100% readiness and prevent cycling during long term inactivity. Some Gel Cell and AGM batteries may require special settings or chargers.

10. Battery Do's Think Safety First. Do read entire tutorial Do regular inspection and maintenance especially in hot weather. Do recharge batteries immediately after discharge. Do buy the highest RC reserve capacity or AH amp hour battery that will fit your

configuration.

11. Battery Don'ts Don't forget safety first. Don't add new electrolyte (acid). Don't use unregulated high output battery chargers to charge batteries. Don't place your equipment and toys into storage without some type of device to

keep the battery charged.

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Don't disconnect battery cables while the engine is running (your battery acts as a filter).

Don't put off recharging batteries. Don't add tap water as it may contain minerals that will contaminate the

electrolyte. Don't discharge a battery any deeper than you possibly have to. Don't let a battery get hot to the touch and boil violently when charging. Don't mix size and types of batteries.

There are many points and details I have not written about because I wanted to keep this

as short and simple as possible. Further information can be found at the links below. If you are aware of sites with good battery

maintenance information please let me know.

CAR AND DEEP CYCLE BATTERY FAQ 2010April 2, 2010

Car and deep cycle battery answers to Frequently Asked Questions (FAQs), tips, manufacturer's information, references and hyperlinks are contained on this consumer oriented Web site about car, power sports (including motorcycle), truck, boat, marine, recreational vehicle, solar, and other starting and deep cycle applications.

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Car Battery Construction (Source: Eurobat)

Car and Deep Cycle Battery Frequently Asked Questions (FAQ) 2010

This consumer oriented FAQ contains answers and information about lead-acid batteries used to start car, truck, boat, recreational vehicle (RV), power sports (including motorcycle), motor home, tractor and other engines. It also answers questions about golf cart, EV, traction, motive, solar, standby, stationary, UPS, network, industrial and other lead-acid batteries used in deep cycle applications. It covers charging (and chargers), testing, buying replacement batteries, installing, myths, overnight draining, removing sulfation, storing (or winterizing), jump starting, and other topics about car (starting) and deep cycle batteries. The FAQ was last updated on April 2, 2010.

Battery Manufacturers and Brand Names List

This popular and frequently updated list contains hyperlinks to lead-acid battery manufacturers' and large distributors' Web sites, telephone numbers, battery brand names, replacement selector and fitment guides, and private labeling information. The file size is approximately 148 KBytes. This list was last updated on April 2, 2010.

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Battery Information Links List

This frequently updated list contains hyperlinks to product information associated with lead-acid batteries, for example, alternators, cables and wiring products, chargers, converters, desulfators, generators, inverters, isolators, low voltage disconnects, jump starters, regulators, solar and PV, switches, test and monitoring systems, etc. The file size is approximately 141 KBytes. This list was last updated on April 2, 2010.

Battery References Link List

This frequently updated list contains hyperlinks to reference resources about lead-acid batteries, for example, 42-volt, associations, books, business directories, dealers and distributors, FAQs, glossaries, history, hyperlink lists, magazines, magazine articles, manuals, primers, newsgroups, safety, standards, etc. The file size is approximately 68 KBytes. This list was last updated on April 2, 2010.

Temperature Compensated Battery State-of-Charge (SoC) Table

When printed, this Excel spreadsheet produces a single page that contains table with the Specific Gravity and Open Circuit Voltage measurements by temperature vs. various States-of-Charges. This is for wet Standard (Sb/Sb), wet Low Maintenance (Ca/Sb), wet "Maintenance Free" (Ca/Ca), AGM VRLA (Ca/Ca), Gel Cell VRLA (Ca/Ca), and SLA (Ca/Ca) Car and Deep Cycle lead-acid batteries. The file size is approximately 22 KBytes.

Battery.Zip

A zipped version of all the above current version battery related Web pages, graphics and spreadsheet on this Web site can be easily down loaded to your computer. Just create a directory for the FAQ and unzip into it. The file size is approximately 1,001 KBytes and was last updated on April 2, 2010.

I will be happy to try and answer your lead-acid battery and charging questions in English within 48 hours. Please inclose a valid "Reply To:" e-mail address in your

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message, to include the word "Battery" somewhere in Subject field, and to insure that your e-mail will not be blocked by my spam filter. All e-mail received with a virus, spam or a worm will be unread and automatically deleted. For questions, errors, omissions, comments, suggestions, or broken link notifications, please send e-mail to infoATbatteryfaqDOT.org. Please replace the AT with an @ and DOT with a period when typing the e-mail address. This is necessary due to the spam and viruses. I apologize for this inconvenience.

I highly recommend that you hyperlink to http://www.batteryfaq.org/ rather than republishing any of these documents because the information is frequently updated to keep up with advancements in batteries and changes in the battery industry, resources, hyperlinks, telephone numbers, etc. Revisions will be indicated with more recent date. These documents are in the public domain and can be freely reproduced or distributed without permission subject to the "fair use" restrictions below. Attribution is always kindly appreciated, but not required.

The Car Battery FAQ was first published on the Internet on June 24, 1995 and the Deep Cycle Battery FAQ on October 24, 2003. The two FAQs were combined into the Car and Deep Cycle Battery FAQ on April 9, 2004 in Version 4.0.

Fair Use Notice

This Web site may contain copyrighted material the use of which has not always been specifically authorized by the copyright owner. I am making such material available in my efforts to advance understanding of educational, economic, and scientific issues, etc., of batteries and not for profit. I believe this constitutes a "fair use" of any such copyrighted material as provided for in section 107 of the United States Copyright Law. In accordance with Title 17 U.S.C. Section 107, the material on this Web site is distributed without profit to those who have expressed a prior interest in receiving the included information for nonprofit educational purposes. For more information see: www.law.cornell.edu/uscode/17/107.shtml. If you wish to use copyrighted material from this Web site for purposes of your own that go beyond "fair use", you must obtain permission from the copyright owner.

1. WHAT IS THE BOTTOM LINE AND TIPS?

BOTTOM LINE:

The six major keys to longer battery service life are:

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Using the battery manufacturer's recommended temperature compensated charging voltages and procedures

Reducing the average Depth-of-Discharge Adding distilled water to wet batteries when

required and practicing good preventive maintenance

Keeping the batteries cool in hot temperatures Reducing the number of discharge-charge cycles Periodically equalizing wet batteries

TIPS:

1.1. Please wear glasses when working with a lead-acid battery in the unlikely event it might explode from the gasses produced during charging. Safety First!

1.2. For a starting battery, at the first signs of slow starting, dim headlights at low RPM, ammeter indicating discharge at higher RPM, or if the battery seems to be losing performance, fully recharge the battery, remove the surface charge, and load test it and the charging system. Some auto parts or battery stores will test your battery, charging system or starter for free. Weak or bad batteries can also cause stress or premature failures of charging systems and starters and vice versa. (Please see Section   4. )

1.3. Perform regular preventive maintenance on starting and deep cycle batteries, especially during hot weather and before cold weather. Keep the battery top clean, cable mating surfaces, posts and terminals free from corrosion, and routinely tighten cable connections and retention alternator belts. Keep non-sealed wet batteries (with filler caps) filled to the proper level with distilled, deionized or demineralized water, but do not overfill or use tap water. The plates must be covered at all times to prevent internal battery explosions or sulfation. (Please see Section   3. )

1.4. In hot climates try and keep batteries as cool as possible. For under the hood, use a non-sealed wet starting battery (with filler caps so you add water) or a sealed spiral wound AGM VRLA battery. (Please see Section   7. )

1.5. For batteries not in weekly use, people kill more deep cycle and starting batteries with bad charging practices than batteries will die of old age. To prevent permanent sulfation and especially in hot weather, in a well ventilated area, keep the battery continuously connected to a "smart" or float charger matched to the battery type; recharge the battery whenever it drops below 80% State-of-Charge (SoC); or use AGM (Ca/Ca) or Gel Cell (Ca/Ca) VRLA battery. A cheap, unattended,

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unregulated "trickle" charger can destroy a battery by overcharging it. (Please see Section   9. for more information on charging and chargers.)

1.6. When buying a replacement starting battery, buy the heaviest and freshest battery compatible with the vehicle's charging system, with the largest Reserve Capacity (RC) and longest free replacement warranty that will physically fit in your vehicle, and sized with the cranking amp rating for the coldest climate the engine is started in. For deep cycle batteries, buy the freshest and heaviest battery with thickest plates and Amp Hour (AH) capacity that best suits the application, matches the charger, and has the lowest Total Cost of Ownership. (Please see Section   7. )

1.7. Avoid a deep discharge (below 20% State-of-Charge or 12.0 VDC) of the battery because this could prematurely kill it, due to cell reversal. After deep discharges or jump-starts, fully recharge a starting battery with an external charger, remove the surface charge, and load test the battery and charging system for latent damage. (Please see Section   4. )

1.8. Temperature and temperature compensation matter! Heat kills batteries and cold reduces their available capacity.

1.9. For longer battery life, do not add battery acid (except to replace electrolyte spills) or additives, keep your battery securely fastened, recharge batteries within 24 hours of each use, use thicker plates, and if recommended by the battery manufacturer, equalize it. Lowering the average Depth-of-Discharge (DoD) percentage will significantly increase the service life of any lead-acid battery. (Please see Section   11. for more information on increasing battery service life.)

1.10. For starting and motive deep cycle batteries, match the charging system (or charger's settings) to the battery type, recharge at 77° F (25° C) unless temperature compensated, and insure that the charging system produces enough power to keep the battery fully charged based of your electrical use and driving habits. Use battery charger (or charger settings) sized not to exceed 25% of the total Amp Hour battery capacity and adjusted to the battery manufacturer's recommended charging voltages with good ventilation, especially when recharging wet non-sealed batteries (with filler caps). A better approach is to slowly recharge your starting and deep cycle batteries over eight to ten hours.

1.11. For negative grounded systems, always jump start 12-volt batteries POSITIVE (+) terminal to POSITIVE (+) terminal and NEGATIVE (-) terminal to the frame or engine block away from the battery or or use AGM (Ca/Ca) or Gel Cell (Ca/Ca) VRLA batteries to greatly reduce the risk of a battery explosion. (Please see Section   6. for more information on jump starting.)

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1.12. For deep cycle batteries, try to avoid shallow discharges (less than 10% Depth-of-Discharge) or deep discharges (more than 80% Depth-of-Discharge or less than 12.0 VDC). This could prematurely kill them. Using an adjustable low voltage disconnect set at 80% Depth-of-Discharge (DoD) or approximately 12.0 VDC will increase the batteries' service life and help protect the batteries and valuable electronic and electrical appliances. (Please see Section   11. )

1.13. Do NOT use wet lead-acid batteries around salt water. If salt water is mixed with the battery's electrolyte, deadly chlorine gas is produced. Only use sealed AGM (Ca/Ca) or Gel Cell (Ca/Ca) VRLA batteries around salt water.

1.14. Remove the surface charge before testing. For non-sealed batteries (with filler caps), use a hydrometer to check Specific Gravity (SG) in each cell because it is more accurate than a DC voltmeter to determine the State-of-Charge (SoC). For sealed batteries, use a accurate (.5% or better) digital DC voltmeter to measure the Open Circuit Voltage (OCV) to determine the SoC. (Please see Section   4. for more information on testing batteries.)

1.15. If the temperature is below 0 degrees F (-17.8 degrees C) and you are not using an AC powered engine block and battery warmer or if the vehicle can not be parked in a warmer location, then disconnect the battery, take it indoors, keep it fully charged, and reconnect it just before starting the engine. (Please see the CCA vs. Temperature Diagram in Section   7.2 ) Alternatively use two 12-volt AGM (Ca/Ca) batteries in parallel and a low viscosity synthetic oil in the engine. Batteries that have less than a 40% State-of-Charge will freeze at 0 degrees F (-17.8 degrees C) and fully discharged batteries will freeze at approximately 20 degrees F (-6.7 degrees C

2. HOW ARE BATTERIES MADE? WORK? and DIE? and WHY NEGATIVELY GROUNDED?

INDEX:

2.1. How Is a Battery Made?

2.2. How Does a Battery Work?

2.3. How Do Batteries Die?

2.4. Why Are Vehicles Negatively Grounded?

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A lead-acid battery (also know as an "accumulator") is a secondary (rechargeable) electrochemical device that stores chemical energy and releases it as electrical energy upon demand. When a battery is connected to an external device, such as a motor, chemical energy is converted to electrical energy and direct current flows through the circuit. In terms of the quantity of lead-acid batteries that are produced, starting batteries represent approximately 88% of the total. The total breaks down to 65% Car, 23% Other Starting Batteries (motorcycle, etc.), 8% Deep Cycle Motive (wheelchairs, golf carts, fork lift trucks, etc.), and 4% Deep Cycle stationary (backup, UPS, standby, etc.).

BATTERY PRODUCTION

In the order of importance, the four major purposes of a car or "SLI" (Starting, Lighting and Ignition) battery, as it is known in the battery industry, are:

To start the engine.

To filter or stabilize the pulsating DC power from the vehicle's charging system.

To provide extra power for the lighting, two-way radios, audio system and other accessories when their combined load exceeds the capability of the vehicle's charging system. This commonly occurs while the vehicle's engine is idling or during short trips with a heavy power load like at night in bad weather.

To supply a source of power to the vehicle's electrical system when the charging system is not operating.

A good quality car battery will cost between $50 and $100 and, if properly maintained, should last five years or more. In 1927, a car battery typically costed

Page 16: Battery Imformation

$70. With a 5% compounded annual growth rate, worldwide retail sales of car lead-acid batteries represent roughly 63% of the estimated $30 billion annually spent on batteries. In North America, BCI reports that 106.6 million car batteries were sold in 2001, of which approximately 80% were for replacement and 20% were for original equipment. For 2003, Eurobat estimates that in Western Europe 58.5 million car batteries will be sold and 71% will be replacement (after market) and 29% will be OEM (Original Equipment Manufacturer). At the Robert W. Baird Industrial Technology Conference, Johnson Controls reported that approximately 350 million starting batteries will be made in the world in 2004. Of that, Johnson Controls is the largest manufacturer with 34% of the total followed by Exide with 14%, GS Yuasa (pending merger of Yuasa and Japan Storage Battery with 10%, Matsushita with 4%, East Penn with 3%, and all others with 35%. In another marketing study by Recharge, in 2003 the worldwide battery market was roughly $30 billion, with 30% of that being SLI (car) and 15.3% industrial (deep cycle) lead-acid batteries.

The purpose of a deep cycle battery is to provide power for wheelchairs, trolling motors, golf carts, boats, fork lift trucks, uninterruptible power supplies (UPS), and other accessories for marine and recreational vehicle (RV), commercial and stationary applications. A good quality wet deep cycle (or "leisure") battery will cost between $50 and $300 and, if properly maintained and used, will give you at least 200 deep discharge-charge cycles. For differences between a car and deep Cycle battery, please see Section 7.1.8. Purportedly, Exide and EnerSys are the two largest deep cycle battery manufacturers in the world.

2.1. How is a Battery Made?

A 12-volt lead-acid battery is made up of six cells, each cell producing approximately 2.11 volts that are connected in series from POSITIVE (+) terminal of the first cell to the NEGATIVE (-) terminal of the second cell and so on. Each cell is made up of an element containing positive plates that are all connected together and negative plates, which are also all connected together. They are individually separated with thin sheets of electrically insulating, porous material "envelopes" or "separators" (in the diagram below) that are used as spacers between the positive (usually light orange) and negative (usually slate gray) plates to keep them from electrically shorting to each other. The plates (in the diagram below), within a cell, alternate with a positive plate, a negative plate and so on.

CAR BATTERY CONSTRUCTION

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[Source: Eurobat]

DEEP CYCLE BATTERY CONSTRUCTION

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[Source: US Department of Energy]

The most common plate type in use today is made up of a metal grid that serves as the supporting framework for the active porous material that is "pasted" on it. After the "curing" of the plates, they are made up into cells, and the cells are inserted into a high-density tough polypropylene or hard rubber case. The positive plates in cells are connected in parallel to the external POSITIVE (+) terminal and the negative plates in each cell are connected to the NEGATIVE (-) external terminal. Instead of pasted Lead Oxide, some batteries are constructed with more expensive solid lead cylindrical (spiral wound); Manchester or "Manchex" (buttons inserted into the grid); tubular; or prismatic (flat) solid lead (Planté) positive plates. The case is covered and then filled with a dilute sulfuric acid electrolyte. The battery is initially charged or "formed" to convert the active yellow Lead Oxide (PbO or Litharge) in the

Page 19: Battery Imformation

positive plates (cathode) into Lead Peroxide (PbO2), which is usually dark brown or black. The active material in the negative pasted plates (anode) becomes sponge Lead (Pb), but with a very porous structure which is slate gray. If sponge Lead is rubbed with a hard object, it will be silvery in color. Antimony (Sb), Calcium (Ca) or other alloys are often added to the plates to enhance their performance or service life. The electrolyte is replaced and the battery is given a finishing charge. A "Wet charged" battery is a wet lead-acid battery shipped with electrolyte in the battery and a "dry charged" battery is shipped without electrolyte. When dry charged batteries are sold, electrolyte (battery acid) is added, allowed to soak into the plates, charged (or "formed"), and put into service. This avoids having to maintain the batteries until they are sold.

PASTED PLATE

[Source: BCI]

FLAT AND TUBULAR PLATE

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PLANTÉ PLATE

[Source: US Department of Energy]

SPIRAL WOUND PLATE

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[Source: US Department of Energy]

Two important considerations in battery construction are porosity and diffusion. Porosity is the pits and tunnels in the plate that allows the sulphuric acid to get to the interior of the plate. Diffusion is the spreading, intermingling and mixing of one fluid with another. When you are using your battery, the fresh acid needs to be in contact with the plate material and the water generated needs to be carried away from the plate. The larger the pores or warmer the electrolyte, the better the diffusion.

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[Source: Varta]

There is an excellent detailed description of how battery is made, equipment used and quality assurance on the Best Manufacturing Practices Web site at http://www.bmpcoe.org/library/books/navso%20p-3676/index.html. If you prefer watching a Quick Time video, Surrette has a first-class one on http://www.surrette.com/rolls/video/video.htm.

[back to Index]

2.2. How Does a Battery Work?

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DISCHARGING PROCESS

PbO2 + Pb + 2H2SO4 → 2PbSO4 + H2O

CHARGING PROCESS (Reverse of Discharging Process)

2PbSO4 + H2O → PbO2 + Pb + 2H2SO4

A battery is created by alternating two different metals such as Lead Dioxide (PbO2), the positive plates, and Sponge lead (Pb), the negative plates. Then the plates are immersed in diluted Sulfuric Acid (H2SO4), the electrolyte. The types of metals and the electrolyte used will determine the output of a cell. A typical fully charged lead-acid battery produces approximately 2.11 volts per cell. The chemical action between the metals and the electrolyte (battery acid) creates the electrical energy. Energy flows from the battery as soon as there is an electrical load, for example, a starter motor, that completes a circuit between the positive terminal connected to the positive plates and the negative terminal connected to the negative plates. Electrical current flows as charged portions of acid (ions) between the battery plates and as electrons through the external circuit. The action of the lead-acid storage battery is determined by chemicals used, State-of-Charge, temperature, porosity, diffusion, and load. A cycle is defined as one discharge and one recharge of the battery.

A more detailed description of how a battery works can be found on the BCI web site at http://www.batterycouncil.org/works.html.

[back to Index]

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2.3. How Do Batteries Die?

When the active material in the plates can no longer sustain a discharge current, a battery "dies". Normally a car (or starting) battery "ages" as the active positive plate material sheds (or flakes off) due to the normal expansion and contraction that occurs during the discharge and charge cycles. This causes a loss of plate capacity and a brown sediment, called sludge or "mud," that builds up in the bottom of the case and can short the plates of a cell out. This will kill the battery as soon as the short occurs. In hot climates, additional causes of failure are positive grid growth, positive grid metal corrosion, negative grid shrinkage, buckling of plates, or loss of water. Deep discharges, heat, vibration, fast charging, and overcharging all accelerate the "aging" process. Approximately 50% of premature car battery failures is caused by the loss of water for normal recharging charging due to the lack of maintenance, evaporation from high under hood heat, or overcharging. Positive grid growth and undercharging causing sulfation also cause premature failures.

Normally well maintained and properly charged deep cycle batteries naturally die due to positive grid corrosion causing an open connection. The shedding of active material is an additional cause. If deep cycle battery is left discharged for long period of time, dendrite shorts between the plates can occur when the battery is recharged. The low resistance bridge in the shorted cell will heat up and boil the electrolyte out of the cell causing a high volumes of hydrogen and oxygen. That is why proper venting and ventilation is so important when recharging batteries. Approximately 85% of premature deep cycle and starting batteries failures that are not recharged on a regular basis is due to an accumulation of sulfation. Sulfation is caused when a battery's State-of-Charge drops below 100% for long periods or under charging. Hard lead sulfate crystals fills the pours and coats the plates. Please see Section   16 for more information on sulfation. Recharging a sulfated battery is like trying to wash your hands with gloves on.

In a hot climate, the harshest environment for a battery, a Johnson Controls survey of junk batteries revealed that the average life of a car battery was 37 months. In a separate North American study by BCI, the average life was 48 months. In a study by Interstate Batteries, the life expectancy in extreme heat was 30 months. If your car battery is more than three years old and you live in a hot

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climate, then your battery is probably living on borrowed time. Abnormally slow cranking, especially on a cold day, is another good indication that your battery is going bad. It should be externally recharged, surface charge removed, and load tested. Dead batteries almost always occur at the most inopportune times. You can easily spend the cost of a new battery or more for an emergency jump start, tow or taxi ride.

Most of the "defective" batteries returned to manufacturers during free replacement warranty periods are good. This strongly suggests that some sellers of new batteries do not know how to or fail to take the time to properly recharge and test batteries. This situation is improving with the widespread use of easy to use battery testers like those made by Cadex, Midtronics and Argus. They are used to predict the capacity of the batteries without having to fully recharge them first.

[back to Index]

2.4. Why Are Vehicles Negatively Grounded?

The best explanation to this question comes from a 1978 Rolls-Royce Enthusiasts' Club service manual.

"...it has been found that cars wired positive earth [ground] tend to suffer from chassis and body corrosion more readily than those wired negative earth. The reason is perfectly simple, since metallic corrosion is an electrolytic process where the anode or positive electrode corrodes sacrificially to the cathode. The phenomenon is made use of in the "Cathodic Protection" of steel-hulled ships and underground pipelines where a less 'noble' or more electro-negative metal such as magnesium or aluminum is allowed to corrode sacrificially to the steel thus inhibiting its corrosion."...

For more information on cathodic protection, please read Roger Alexander's article, An idiots guide to cathodic protection or Chris Gibson's article What is Galvanic Erosion, is it serious and can it be prevented? for metal boat hulls. By 1956, all the North American manufactured cars and trucks, except the Metropolitan, were using negative earth [grounding]. For more specific information on grounding systems used in North American vehicles, please see

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the Antique Automobile Radio's chart on http://www.antiqueautomobileradio.com/battery.htm.

3. HOW DO I PERFORM PREVENTIVE MAINTENANCE?

Performing preventive maintenance on batteries is easy and should occur at least once a month during hot weather and every three months in cold weather. While working with car and deep cycle lead-acid batteries (and corrosion), please wear glasses to protect your eyes in the unlike even of an explosion. Here are some simple steps to maintain your battery:

3.1. Before you start the engine for the first time during the day, check the electrolyte level for non-sealed wet batteries (with filler caps). If above the plates and for all other battery types, check the State-of-Charge (SoC) of the battery. Please see Section   4.4 for more information on determining the SoC. If the battery is not fully charged (100% State-of-Charge), recharge it with an external battery charger in a well ventilated area. Please see Section   9 for more information on charging. This is because State-of-Charge is based on your driving habits. Some vehicle charging systems have been known to consistently undercharge the battery causing an accumulation of lead sulfate, know as sulfation. A gradual build up of sulfation will reduce the capacity of the battery. Periodically fully recharging with an external charger will restore most or all of the battery's capacity. Once per month is recommended during summer and every three months during winter.

3.2. Checking electrolyte levels of non-sealed (with filler caps) batteries once per month is recommended during summer and every three months during winter. The plates need to be covered at all times to prevent sulfation and reduce the possibility of an internal battery explosion. For non-sealed wet car batteries and small deep cycle batteries (less than 200 amp hours) with low electrolyte levels, recharge the battery first and allow the battery to cool to room temperature. Then add only distilled, deionized or demineralized water to the level indicated by the battery manufacturer or just to the bottom of the filler tubes (vent wells or splash barrels) as shown in the diagram below. On large deep cycle batteries, fill to within 1/4 to 3/8 inch (6 to 10 mm) below the bottom of the filler tubes. Avoid overfilling, especially in hot weather, because the heat will cause the electrolyte to expand and overflow. In an emergency, use rain water. Do not use tap water or water from residential Reverse Osmosis (RO) systems to refill batteries because it could contain chlorine, calcium or magnesium and produce chlorine gas or calcium or magnesium sulfate crystals. These crystals can gradually fill the pores or coat the plates which will reduce the battery's capacity and cause premature failure.

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State-of-Charge (SoC) readings will be inaccurate immediately after the addition of water, recharges or discharges. Please see Section   4.3 for more information on removing a Surface Charge.

ELECTROLYTE FILL LEVELS FOR SMALL BATTERIESLess Than 200 AH

[Source: Exide]

ELECTROLYTE FILL LEVELS FOR LARGER BATTERIESGreater Than 200 AH

[Source: Mountain Top Golf Cars]

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To reduce the water consumption for wet batteries, there are special battery caps, for example, Hydocaps, Water-Mizer, etc. that are specifically designed for that purpose. To water the batteries, there are watering systems available that will add water to each battery cell. Please see Watering Systems and Battery Filler Caps for more information. If electrolyte has been spilled, please see Section   9.14 for more information on adding electrolyte or adjusting the Specific Gravity within a cell. If a battery has dried out due to an overcharge, you can try to recovery it by refilling with distilled water and slowly recharging it. It might take several discharge/charge cycles before some or all of the capacity is restored.

3.3. Remove any corrosion, lead oxidation, paint or rust with a brass wire battery brush or with a "ScotchBrite" pad from the terminal's mating surfaces on both ends of each battery cables, battery posts, lugs or terminals, and engine grounding strap connections. For safety, brush the corrosion away from you and wear eye protection. A stiff steel wire brush or sandpaper may damage protective lead plating on copper connectors or terminals. Corrosion is normally a white powdery substance, but could have other colors mixed in with it like gray, yellow or green. Heavy corrosion can be neutralized with a mixture of one pound of baking soda (bicarbonate of soda) to one gallon of warm water. Some folks have been known to use Diet Coke or Pepsi to dissolve corrosion. You are probably thinking why "diet"? Diet is used because it does not contain sugar which will leave a sticky residue. Bare metal to metal mating surfaces are required for very low electrical resistance and good current conductivity.

To prevent corrosion caused by batteries located under the hood, thinly coat the terminals, posts, terminal clamps, lugs and exposed metal around the battery with high temperature and water resistant wheel bearing grease, lithium grease or silicone. Petroleum jelly (Vaseline) or Calcium grease is not recommended for use under the hood because they have a low melting point. Gluing a sacrificial anode, such as a piece of copper to the top of the battery between the posts or using VRLA batteries will prevent or reduce terminal corrosion. Do not use the felt or metal washers between the mating conductive surfaces with General Motors-type side terminals. For car or deep cycle batteries not subject to high temperatures, use "No Oxide A" (or the battery manufacturer's recommended grease) on the posts, lugs, terminals or connectors. Do not use the felt or metal washers between the mating conductive surfaces with side, stud or "L" terminal batteries. Use of some stainless steel alloys and other metal lugs, washers, nuts and bolts have also been known to cause problems with electrolysis and high resistance.

Corrosion is caused by one or more the following:

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Dirty or wet battery tops normally caused from expansion of electrolyte from overfilled cells or weeping from faulty battery terminal seals

Acid fumes leaking through the vent caps, which could be a sign of overcharging

Not enough battery box or room ventilation Electrolysis due to the mismatch of metal alloys used

in the battery posts, lugs, terminal clamps or terminals

3.4. Tighten loose hold-down clamps to prevent excessive vibration, battery lugs, terminals and connectors.

3.5. Clean the battery top to eliminate conductive paths created by dried or wet electrolyte and to prevent corrosion.

3.6. Clean the alternator or charging system to allow better heat transfer and check the alternator belts for cracks and correct tension.

3.7. Replace any battery cables (or cable terminals) that are corroding, swelling or damaged with equal or larger diameter cable. If electrical problems are experienced in vehicles with GM's side terminal connectors, check for corrosion inside the positive terminal, lug or connector with the multiple cables. Larger cable and lugs, connectors or terminals are better because there is more surface area and less voltage drop. Please see Exide's Voltage Drop in Cables for additional information.

3.8. Replace the battery if the battery case is bulging, cracked or leaking, especially around "GM" style side terminals.

3.9. Periodically rotate batteries in a bank because the lowest capacity batteries tend to fail first and to insure that the connections are clean and tight.

4. HOW DO I TEST A BATTERY?

INDEX:

4.1. Inspect

4.2. Charge

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4.3. Remove Surface Charge

4.4. Measure State-of-Charge (SoC)

4.4.1. Specific Gravity vs. Temperature at Various States-Of-Charge (SoC) for a Wet Low Maintenance (Sb/Ca) or Standard (Sb/Sb) Battery Table

How Do I Use a Hydrometer?

Electrolyte Freeze Points Table

4.4.2. Open Circuit Voltage vs. Temperature at Various States-Of-Charge (SoC) for a Wet Low Maintenance (Sb/Ca) or Standard (Sb/Sb) Battery Table

4.4.3. Open Circuit Voltage vs. Temperature at Various States Of Charge (SoC) for a Wet "Maintenance Free" (Ca/Ca) or VRLA (AGM or Gel Cell) Battery Table

4.4.4. Interpreting the SoC Measurements

4.5. Performance or Capacity Load Testing

Performance Load Test Table

4.6. Bounce Back Test

4.7. Recharge

4.8. Refill

While working with car or deep cycle lead-acid batteries, please help to prevent blindness by wearing glasses in the unlikely event of an explosion. Below are eight simple steps in performance and capacity testing a battery. Alternatively, some auto parts or battery stores in the United States and Canada, like Auto Zone, Sears, Wal-Mart, Pep Boys, etc., will test your battery, charging system and starter for free. If you have a non-sealed wet battery (with filler caps), it is highly recommended that you use a good quality temperature compensating hydrometer, like an E-Z   Red   SP101 , which can be purchased online or at an auto parts or battery store for less than $10.

If you have a sealed battery or need to troubleshoot a charging or electrical system, you will need a digital voltmeter with 0.5% (or better) DC accuracy, such as a Fluke 73-3 or 175. A digital voltmeter (or multimeter) can be purchased at an electronics store for between $20 and $200. A good, free digital multimeter

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applications manual for testing electrical systems is available on-line from Fluke at http://us.fluke.com/usen/support/appnotes/default?category=AP_AUTO(FlukeProducts). Analog voltmeters are not accurate enough to measure the millivolt differences of a battery's State-of-Charge or output of the charging system. Do not use a 12-volt test light to troubleshoot vehicle electrical circuits, except for testing the parasitic load at the battery, because you might damage the emissions computer or other sensitive electronic devices. A good source of information on measuring voltage and for maximum voltage drops can be found at Exide's Caring For Your Battery. A battery performance load tester is optional. For batteries with at least a 50% State-of-Charge, another way of testing the CCA (Cold Cranking Amp) starting performance or Reserve Capacity (RC) or amp hour (AH) capacity of lead-acid batteries is using an electro-chemical impedance spectroscopy (EIS) tester, such as a Cadex Spectro CA-12 or a conductance tester, for example a Argus or Midtronics.

A sulfated sealed battery's voltage often will read higher than the SoC actually is, so load testing maybe required to determine the battery's actual performance or capacity.

[back to Index]

4.1. Inspect

Inspect for obvious problems such as a low electrolyte levels; loose, corroded or swollen cables, corroded battery terminals or posts; loose or broken alternator belt; frozen battery; loose hold-down clamps; dirty or wet battery top; or a leaking, cracked, bulging or damaged battery case or terminals. If the electrolyte levels are below the tops of the plates, add enough distilled, deionized or demineralized water to cover the plates and recharge the battery, allow to cool to room temperature and then top off the levels. The plates need to be covered at all times to prevent sulfation and reduce the possibility of an internal battery explosion. Please see Section   3.2 for electrolyte fill level information.

If electrolyte has been spilled, please see Section   9.14 for more information on adding electrolyte or adjusting the Specific Gravity within a cell.

4.2. Charge

Charge the battery to 100% State-of-Charge in a well ventilated area. If non-sealed wet battery has a .030 (sometimes expressed as 30 "points") or more difference in Specific Gravity reading

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between the lowest and highest cell or if a cell is .010 or 10 "points" below the reading for a fully charged cell, then you should equalize the battery using the battery manufacturer's procedures. (Please see Section   9 . for more information on equalize charging.)

[back to Index]

4.3. Remove Surface Charge

Surface charge (or "counter voltage") is the uneven mixture of sulfuric acid and water along the surface of the plates as a result of charging or discharging as the electrolyte has an opportunity to diffuse in the pores of the plates. It will make a weak battery appear good or a good battery appear bad. Larger wet lead-acid batteries (especially over 100 amp hours) could also have electrolyte stratification where the concentration of acid is greater at the bottom of the cell than near the surface. The Open Circuit Voltages (OCV) will read higher than they actually are. Stratification can be eliminated by an equalizing charge, stirring or gently shaking the battery to mix the electrolyte.

A surface charge can be eliminated by one of the following methods after recharging a lead-acid battery:

Allow the car or deep cycle battery to sit (or rest) without discharge or charge for between two and eight hours at room temperature, if possible, to allow for the surface charge to dissipate. (Recommended method.)

For car batteries, turn the headlights on high beam for five minutes and wait ten minutes.

For car batteries, apply a load with a battery load tester at one-half the battery's CCA rating for 15 seconds and then wait ten minutes.

For car batteries, disable the ignition, turn the engine over for 15 seconds with the starter motor, and wait ten minutes.

For deep cycle batteries, apply a load that is 33% of the amp-hour capacity for five minutes and wait at least ten minutes.

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4.4. Measure the State-of-Charge (SoC)

The State-of-Charge acts like a "battery fuel gauge", but it only measures the state of the battery's charge and not it's storage capacity, or state of health to produce rated starting current or performance. For storage capacity measurements, please see Section   4.5 , below. For example, a 50% SoC reading does not necessarily mean that a 100 amp hour (C/20) battery will produce 50 amp hours at five amp discharge load (with five amps being the 20 hour discharge load) or starting current. This is because the battery might not have a 100 amp hours of storage capacity to begin with. Depth-of-Discharge (DoD) is the inverse of State-of-Charge (SoC) as shown in the following graphic.

[Source: Andre Packwood]

To measure a battery's State-of-Charge, perform the following steps:

If the battery's electrolyte is above 120° F (48.9° C), allow it to cool.

Measure the electrolyte temperature (Recommended). If the battery has not been charged or discharged within the last four hours, the ambient or surrounding air temperature can be used.

Measure Specific Gravity of each cell of wet, non-sealed (with filler caps) wet lead-acid batteries with a hydrometer or Open Circuit Voltage (OCV) of sealed wet and VRLA batteries with an accurate (.5% or better) digital voltmeter.

If the battery manufacturer's State-of-Charge (SoC) specifications are not available for the battery, select the appropriate table below for the appropriate battery

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type for an approximation. If you are unsure about the battery type, please refer to Section   7.1 for more information. For wet, non-sealed (with filler caps) Low Maintenance (Sb/Ca) or Standard (Sb/Sb) lead-acid batteries, use the Specific Gravity vs. Temperature at Various States-Of-Charge (SoC) for a Wet Low Maintenance (Sb/Ca) or Standard (Sb/Sb) Battery Table or Open Circuit Voltage (OCV) vs. Temperature at Various States-Of-Charge (SoC) for a Wet Low Maintenance (Sb/Ca) or Standard (Sb/Sb) Battery Table. For wet, sealed "Maintenance Free" (Ca/Ca) or VRLA (AGM or Gel Cell) lead-acid batteries, use the Open Circuit Voltage (OCV) vs. Temperature at Various States-Of-Charge (SoC) for a Wet "Maintenance Free" (Ca/Ca) Battery Table.

Based on the electrolyte (or ambient) temperature and the measurement, determine the State-of-Charge (SoC) from the appropriate temperature row and SoC column in the table selected. Some interpolation may be required.

A downloadable Temperature Compensated Battery State-of-Charge (SoC) Table is available. When printed, this Excel spreadsheet produces a single page that contains table with the Specific Gravity and Open Circuit Voltage measurements by temperature vs. various States-of-Charges. This table is for wet Low Maintenance (Ca/Sb), wet Standard (Sb/Sb), and wet "Maintenance Free" (Ca/Ca) or VRLA (AGM or Gel Cell) batteries. The file size is approximately 22 KBytes.

[back to Index]

4.4.1. Specific Gravity vs. Temperature at Various States-Of-Charge (SoC) for a Wet Low Maintenance (Sb/Ca) or Standard (Sb/Sb) Battery Table

Using a temperature compensated hydrometer to measure the Specific Gravity is the most accurate way of determining a wet, non-sealed (with filler caps) lead-acid battery's SoC. When the SoC measured by a hydrometer does not materially agree with the SoC measured by an accurate digital voltmeter, it is probably due to sulfation. If you suspect that a battery is sulfated, it probably is, especially if it will not hold a charge, has not been charged in a while, or has been continuously undercharged. For more on sulfation, please

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see Section   16 . This table has a baseline that assumes that a 1.265 Specific Gravity (SG) reading for a fully charged (100% SoC), wet Low Maintenance (Sb/Ca) or Standard (Sb/Sb) lead-acid battery at rest at 80° F (26.7° C). The Specific Gravity readings for a battery at 100% SoC will vary by plate chemistry, so if possible, check the battery manufacturer's specifications for their State-of-Charge definitions for the battery being measured. If the baseline is unknown at 100% SoC, please see Section   9.5. How Do I Know When My Battery Is Fully Charged? Depending on the plate chemistry, the Specific Gravity can range from 1.215 to 1.300 for a fully charged wet Low Maintenance (Sb/Ca) or Standard (Sb/Sb) car batteries at 80° F (26.7° C) and tend to be higher in deep cycle batteries.

Specific Gravity vs. Temperatureat Various States-Of-Charge (SoC)for a Wet Low Maintenance (Sb/Ca)or Standard (Sb/Sb) Battery Table

Electrolyte Temperature (Fahrenheit)

Electrolyte Temperature

(Celsius)

100% SoC

75% SoC

50% SoC

25% SoC

0% SoC

120° 48.9° 1.249 1.209 1.174 1.139 1.104110° 43.3° 1.253 1.213 1.178 1.143 1.108100° 37.8° 1.257 1.217 1.182 1.147 1.11290° 32.2° 1.261 1.221 1.186 1.151 1.11680° 26.7° 1.265 1.225 1.190 1.155 1.12070° 21.1° 1.269 1.229 1.194 1.159 1.12460° 15.6° 1.273 1.233 1.198 1.163 1.12850° 10.0° 1.277 1.237 1.202 1.167 1.13240° 4.4° 1.281 1.241 1.206 1.171 1.13630° -1.1° 1.285 1.245 1.210 1.175 1.14020° -6.7° 1.289 1.249 1.214 1.179 1.14410° -12.2° 1.293 1.253 1.218 1.183 1.1480° -17.8° 1.297 1.257 1.222 1.187 1.152

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For example, if the electrolyte is at 20° F (-6.7° C), the Specific Gravity reading would be 1.289 for a 100% State-of-Charge because the liquid is more dense at the colder temperature. At 100° F (37.8° C), the Specific Gravity reading would be 1.182 for 50% SoC and a reading of 1.104 or lower at 120° F (48.9° C) would indicate a discharged battery.

[back to Index]

HOW DO I USE A HYDROMETER?

A hydrometer is an inexpensive float-type device used to measure the concentration of sulfuric acid (Specific Gravity) of battery electrolyte ("battery acid"). From this reading you can easily and accurately determine a non-sealed battery's State-of-Charge. A hydrometer is a glass barrel or plastic container with a rubber nozzle or hose on one end and a soft rubber bulb on the other. Inside the barrel or container, there is a float and calibrated graduations used for the Specific Gravity measurement. The following is a list of instructions on how to correctly use a battery hydrometer:

BATTERY HYDROMETERS

[Source: Popular   Mechanics ]

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[E-Z Red   SP101 ]

1. If the battery's electrolyte is above 120° F (48.9° C), allow it to cool.

2. If the battery has been charged or discharged within the last four hours, remove the Surface Charge.

3. Wear some glasses, preferably safety glasses, in the unlikely event that a battery explosion or electrolyte spill might occur.

4. While holding a clean hydrometer vertically, squeeze the rubber bulb, insert the nozzle into the electrolyte in the cell, and release the bulb. The electrolyte will be sucked up into the barrel or container allowing the float to ride freely. Start with the cell that is closest to the POSITIVE (+) terminal.

5. Tap the hydrometer to dislodge any air bubbles on the float.

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6. Squeeze the rubber bulb to release the electrolyte back into the battery's cell.

7. To increase the accuracy of the measurement, in the same cell, repeat this process several times so the float will reach the same temperature as the electrolyte. If you are measuring a large battery, stratification can occur when the more concentrated electrolyte settles to the bottom. In large deep cycle batteries, if you notice a difference in the readings from electrolyte taken at the top and bottom of the cell, average the two readings.

8. At eye level and with the float steady, read the Specific Gravity at the point the surface of the electrolyte crosses the float markings. The Specific Gravity reading should be between 1.100 and 1.300.

9. Release the electrolyte back into the cell from which it was taken and record the reading. Be sure to avoid spillage.

10. If the hydrometer is not temperature compensating, measure the electrolyte temperature and use the appropriate temperature row and SoC column in the Specific Gravity vs. Temperature at Various States-Of-Charge (SoC) for a Wet Low Maintenance (Sb/Ca) or Standard (Sb/Sb) Battery Table to determine the SoC. If the hydrometer is temperature compensating, determine the State-of-Charge from the hydrometer or the 80° F (26.7° C) temperature row and SoC column in the Specific Gravity vs. Temperature at Various States-Of-Charge (SoC) for a Wet Low Maintenance (Sb/Ca) or Standard (Sb/Sb) Battery Table.

11.Repeat the process for each individual cell. The Specific Gravity reading should not have a difference of more that 30 "points" (.030) between the lowest and highest reading or 10 "points" (.010) below the battery manufacturer's recommended temperature value with the battery fully charged. If so, try and equalize the battery by following the battery manufacturer's procedures or the procedure in Section   9 . If equalizing does not help, replace the battery.

12.Determine the battery's State-of-Charge (SoC) by taking the average of the cell readings, but the battery's performance and capacity will be based on the weakest cell.

13.Throughly rinse the hydrometer with water after using it.

[back to Index]

Electrolyte Freeze Pointsat Various States-of-Charge

for a Wet Lead-Acid Battery Table

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ApproximateState-of-Charge

(SoC)

ApproximateDepth-of-Discharge

(DoD)

Approximate Electrolyte Freeze

Point100% 0% -77°F

(-67°C)75% 25% -35°F

(-37°C)50% 50% -10°F

(-23°C)25% 75% 5°F

(-15°C)0%

(DISCHARGED)100%

(DISCHARGED)20°F

(-6.7°C)

[back to Index]

4.4.2. Open Circuit Voltage vs. Temperature at Various States Of Charge (SoC) for a Wet Low Maintenance (Sb/Ca) or Standard (Sb/Sb) Battery Table

If the battery is sealed, then use an accurate (.5% or better) digital voltmeter to measure the battery's Open Circuit Voltage (OCV) to determine the SoC. When the SoC measured by a hydrometer does not materially agree with the SoC measured by a digital voltmeter, it is probably due to sulfation. If you suspect that a battery is sulfated, it probably is, especially if it has not been charged in a while or has been continuously undercharged. For more on sulfation, please see Section   16 This table has a baseline that assumes that a 12.65 Open Circuit Voltage (OCV) reading for a fully charged (100% SoC), wet Low Maintenance (Sb/Ca) or Standard (Sb/Sb) lead-acid battery at rest, 80° F (26.7° C), and with the negative terminal disconnected. The OCV readings for a battery at 100% SoC will vary by plate chemistry, so if possible, check the battery manufacturer's specifications for their State-of-Charge definitions for the battery being measured. Depending on the plate chemistry, the Open Circuit Voltage can range from 12.22 to 13.00 for a fully charged wet Low Maintenance (Sb/Ca) or Standard (Sb/Sb) battery at 80° F (26.7° C). Deep Cycle batteries tend to have higher voltages than car batteries.

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Open Circuit Voltage (OCV) vs. Temperatureat Various States Of Charge (SoC)for Wet Low Maintenance (Sb/Ca)or Standard (Sb/Sb) Battery Table

Electrolyte Temperature (Fahrenheit)

Electrolyte Temperature

(Celsius)

100% SoC

75% SoC

50% SoC

25% SoC

0% SoC

120° 48.9° 12.663 12.463 12.253 12.073 11.903110° 43.3° 12.661 12.462 12.251 12.071 11.901100° 37.8° 12.658 12.458 12.248 12.068 11.89890° 32.2° 12.655 12.455 12.245 12.065 11.89580° 26.7° 12.650 12.450 12.240 12.060 11.89070° 21.1° 12.643 12.443 12.233 12.053 11.88360° 15.6° 12.634 12.434 12.224 12.044 11.87450° 10.0° 12.622 12.422 12.212 12.032 11.86240° 4.4° 12.606 12.406 12.196 12.016 11.84630° -1.1° 12.588 12.388 12.178 11.998 11.82820° -6.7° 12.566 12.366 12.156 11.976 11.80610° -12.2° 12.542 12.342 12.132 11.952 11.7820° -17.8° 12.516 12.316 12.106 11.926 11.756

For example, if the electrolyte is at 20° F (-6.7° C), the Open Circuit Voltage reading would be 12.566 for a 100% State-of-Charge. At 100° F (37.8° C), the Open Circuit Voltage reading would be 12.248 for 50% SoC and a reading of 11.903 or lower at 120° F (48.9° C) would indicate a discharged battery.

4.4.3. Open Circuit Voltage vs. Temperature at Various States Of Charge (SoC) for a Wet "Maintenance Free" (Ca/Ca) or VRLA (AGM or Gel Cell) Battery Table

If the battery is sealed, then use an accurate (.5% or better) digital voltmeter to measure the battery's Open Circuit

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Voltage (OCV) to determine the SoC. This table has a baseline that assumes that a 12.78 Open Circuit Voltage (OCV) reading for a fully charged (100% SoC), wet "Maintenance Free" (Ca/Ca) battery at rest, 80° F (26.7° C) with the negative terminal disconnected. The OCV readings for a battery at 100% SoC will vary by plate chemistry, so if possible, check the battery manufacturer's specifications for their State-of-Charge definitions for the battery being measured. Depending on the plate chemistry, the Open Circuit Voltage can range from 12.6 to 13.1 for fully charged wet "Maintenance Free" (Ca/Ca) batteries and tend to be higher in deep cycle than in car (or starting) batteries. Some sealed wet "Maintenance Free" batteries have a built-in hydrometer, "Magic Eye", which only measures the State-of-Charge in ONE of its six cells.

"Magic Eye" Built-in Hydrometer

[Source: Popular Mechanics]

Open Circuit Voltage (OCV) vs. Temperatureat Various States-Of-Charge (SoC)

for a Wet "Maintenance Free" (Ca/Ca)or VRLA (AGM or Gel Cell) Battery Table

Electrolyte Temperature (Fahrenheit)

Electrolyte Temperature

(Celsius)

100% SoC

75% SoC

65% SoC

50% SoC

25% SoC

0% SoC

120° 48.9° 12.793 12.563 12.463 12.313 12.013 11.773

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110° 43.3° 12.791 12.561 12.461 12.311 12.011 11.771100° 37.8° 12.788 12.558 12.458 12.308 12.008 11.76890° 32.2° 12.785 12.555 12.455 12.305 12.005 11.76580° 26.7° 12.780 12.550 12.450 12.300 12.000 11.76070° 21.1° 12.773 12.543 12.443 12.293 11.993 11.75360° 15.6° 12.764 12.534 12.434 12.284 11.984 11.74450° 10.0° 12.752 12.522 12.422 12.272 11.972 11.73240° 4.4° 12.736 12.506 12.406 12.256 11.956 11.71630° -1.1° 12.718 12.488 12.388 12.238 11.938 11.69820° -6.7° 12.696 12.466 12.366 12.216 11.916 11.67610° -12.2° 12.672 12.442 12.342 12.192 11.892 11.6520° -17.8° 12.646 12.416 12.316 12.166 11.866 11.626

For example, if the electrolyte is at 20° F (-6.7° C), the Open Circuit Voltage reading would be 12.696 for a 100% State-of-Charge. At 100° F (37.8° C), the Open Circuit Voltage reading would be 12.308 for 50% SoC and a reading of 11.773 or lower at 120° F (48.9° C) would indicate a discharged battery.

[back to Index]

4.4.4. Interpreting the SoC Measurements

If the State-of-Charge is BELOW 75% using either the Specific Gravity, voltage test or the built-in hydrometer does not indicate "good" (green or blue), then the battery has a low charge and needs to be recharged before proceeding. If the battery is sealed, the battery could have low electrolyte, especially in a hot climate. You should replace the battery, if one of the following conditions occur:

If there is a .050 (sometimes expressed as 50 "points") or more difference in the specific gravity reading between the highest and lowest cell, you have a weak or dead cell(s). Applying an EQUALIZING charge per the battery manufacturer's procedures may correct this condition. (Please see Section   9. )

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If the battery will not recharge to a 75% or more State-of-Charge level or if the built-in hydrometer still does not indicate "good" (green or blue), which indicates a 65% SoC or better).

If a moderate load is applied and if there is no or very little current flowing there is an probably an open cell or a completely sulfated battery. Without a load, a voltmeter reading may or may not indicate an open.

If the digital voltmeter indicates 10.45 to 10.65 volts, there probably is a shorted cell. A shorted cell is caused by plates touching, sediment ("mud") build-up or "treeing" between the plates.

[back to Index]

4.5. Performance or Capacity Load Testing

Performance load testing is used to determining a battery's ability to produce current. Capacity load testing is for determining the Reserve Capacity or Amp Hour capacity of a battery. The primarily purpose of a car battery is to start an engine, so the battery's performance (or ability to produce high current) is an important test.

A battery's internal resistance can be computed using the following formula: Internal Resistance = Voltage Drop / Load Current.

4.5.1. Battery's Performance (High Current Method)

If the battery's State-of-Charge is at 75% or higher or has a "good" built-in hydrometer indication, then you can load test the battery by one of the following methods:

With a battery conductance tester, test the battery. Please note that the accuracy of conductance testing improves with the battery at a 50% or more State-of-Charge. Most auto dealerships, auto parts and battery stores have battery conductance testers and some will test battery performance or capacity for free. (Recommended method).

With a battery load tester, apply a load equal to one half of the CCA rating of the battery for 15 seconds.

With a battery load tester, apply a load equal to one half the OEM cold cranking amp specification for 15 seconds.

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Disable the ignition and turn the engine over for 15 seconds with the starter motor.

DURING the load test, the voltage on a healthy battery will NOT drop below the following table's indicated voltage for the electrolyte at the temperatures shown:

Performance Load TestElectrolyte

Temperature Fahrenheit

Electrolyte Temperature

Celsius

Minimum Voltage Under

LOAD100° 37.8° 9.990° 32.2° 9.880° 26.7° 9.770° 21.1° 9.660° 15.6° 9.550° 10.0° 9.440° 4.4° 9.330° -1.1° 9.120° -6.7° 8.910° -12.2° 8.70° -17.8° 8.5

[Source: BCI]

[back to Index]

4.5.2. Battery Capacity (Low Current Method)

Batteries with Reserve Capacity or Amp Hour capacity ratings can be capacity tested using a slow discharge load test. A DC ammeter and an adjustable resistive load, for example, 12-volt lamps wired in parallel, are required for this test. Please note that this test will not test the battery's performance (ability to produce enough high current to start an engine), but if a battery fails this test, it will probably also fail the high current load capacity test in Section 4.5.1 above.

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If the battery is fully charged, the surface charge has been removed, and you know the Reserve Capacity (RC) rating of the battery, then you can test the Reserve Capacity of a battery by applying a constant 25 amp load and discharging the battery of it's rated Reserve Capacity in minutes as defined by the battery manufacturer. For example, if you have an 120 minute RC rated battery, then at 80 degrees F (26.7 degrees C) measure the number of minutes it takes to discharge a fully charged battery with a constant 25 amp load to 10.5 volts. Do not discharge the battery below 10.5 volts because you could damage the battery.

If the battery is fully charged, the surface charge has been removed, and you know the Amp Hour rating of the battery, then you can test the capacity of a battery by applying a specific load and discharging the battery of it's rated amp hour capacity as defined by the battery manufacturer. Normally the discharge load is the resistance that will discharge a battery in 20 hours (C/20) for car (SLI) and motive deep cycle batteries and eight hours (C/8) for stationary deep cycle batteries. For example, if you have an 100 ampere-hour (C/20) rated battery, then an constant load of five amps would discharge the battery to it's rated amp hour capacity in approximately 20 hours (100 AH / 20 Hours = 5 Amps). To determine the capacity, at 80 degrees F (26.7 degrees C) measure the number of hours it takes to discharge a fully charged battery at the discharge rate to 10.5 volts. As the battery discharges, the resistance will have to be decreased to maintain the constant discharge load, at five amps in this example. Do not discharge the battery below 10.5 volts because you could damage the battery.

A battery with 80% or more of it's manufacturer's original rated capacity or performance is considered to be good for most applications. Some new batteries can take up to 30 charge/discharge "preconditioning" cycles before they reach their rated capacity. If the battery passed the Capacity Load Test, then skip the next test, Section 4.6 Bounce Back Test and go to Section   4.7. Recharge below.

[back to Index]

4.6. Bounce Back Test

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If the battery has passed the high current performance test, please go to Section   4.7. Recharge below. If not, remove the load, wait ten minutes, and measure the State-of-Charge. If the battery bounces back to less than 75% SoC then recharge the battery (please see Section   9 .) and load test again. If the battery fails the load test a second time or bounces back to less than 75% SoC, then replace the battery because it lacks the necessary high current (CCA) performance.

[back to Index]

4.7. Recharge

In a well ventilated area, you should recharge your battery to 100% SoC as soon as possible to prevent lead sulfation and to restore it to peak performance.

[back to Index]

4.8. Refill

When the non-sealed wet battery (with filler caps) has cooled to room temperature, recheck the electrolyte levels and, if necessary, fill to the correct levels with distilled water. Please see Section   3.2 for electrolyte fill level information.

5. HOW DO I KNOW IF MY VEHICLE'S CHARGING SYSTEM IS OK OR LARGE ENOUGH?

INDEX:

5.1. How Does A Vehicle Charging System Work?

Charging System Functional Diagram

Alternator Output Graph

Vehicle Charging Voltage Graph

5.2. What If My "Battery" or "Alternator" Light Is On? (Or the Gauge Is Not Showing a "Charging" Condition?)

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5.3. What If I Cannot Keep My Battery Charged and the Battery Tests OK?

5.4. How Can I Test To Determine If Charging System Is Large Enough?

5.1. How Does A Vehicle Charging System Work?

Referring to Dan Masters' diagram below, a vehicle's charging system is composed of an alternator (or DC generator), voltage regulator, battery, and indicator light or gauge. A good source of information on the basics of vehicle charging systems can be found on Perry Babin's Basic Car Audio Electronics Web site at http://www.bcae1.com/charging.htm. A detailed description of how and alternator works is in Nathen Eagle's article Using an Alternator in Renewable Energy Projects or Bob Hewitt's article Alternators - what are they, how do they work and what breaks??.

While the engine is running, the charging system's primary purpose is to provide power for the car's electrical load, for example, ignition, lighting, audio system, accessories, etc., and to recharge your vehicle's battery. The alternator's output capacity is directly proportional to the RPM of the engine and alternator temperature. Charging systems are normally sized by the car manufacturers to provide at least 125% (when operating at high RPM) of the worst-case OEM (Original Equipment Manufacturer) electrical load, so that the car battery can be recharged. That is the reason that short, stop and go driving at night or in bad weather might not keep the battery fully recharged, especially if the electrical load has been increased with after market accessories, such as high power audio equipment, lighting or an electric winch. Vehicle charging systems are not designed to recharge fully discharged batteries and doing so may damage the stator or diodes from overheating.

CHARGING SYSTEM FUNCTIONAL DIAGRAM

Page 48: Battery Imformation

[Source: Vintage   Triumph   Register ]

In the Balmar Alternator Output diagram below, the power output curves are shown for 65 amp and 85 amp alternators. Note that the 65 amp alternator in this example produces more current output (power) at a lower RPM that does the larger alternator until approximately 3300 RPM. Also note the difference that the crankshaft pulley size makes. A larger crankshaft pulley will create a higher alternator RPM, thus causing the alternator to produce more power at a lower engine RPM.

ALTERNATOR OUTPUT GRAPH

Page 49: Battery Imformation

[Source: Balmar]

When the charging system fails, usually a "battery" or "alternator" warning indicator or light will come on or the voltage (or amp) gauge will not register "good". If you increase the engine speed and the alternator light becomes brighter, then the battery needs to be fully recharged and tested. If the light becomes dimmer then the problem is most likely in the charging system. Another simple charging system test is with the engine running shine the headlights against a wall at night. If you turn the engine off and the lights get dimmer, then the charging system is producing a higher voltage. If the light becomes brighter, then you probably have a charging system problem. The indicator (also known as an "idiot") light is a direct comparison between the voltage output of charging system and the voltage output of the battery. The next test requires use of a known-to-be-good, fully charged battery. Temporarily replace the old battery with this battery and run the engine at 2500 RPM or more for two minutes. Depending on the load and ambient temperature, the voltage should increase to between 13.0 and 15.1 volts during this period. Most vehicles with good charging systems will measure between 13.8 and 14.8 volts on a warm day, depending on the battery type that the charging system was designed for.

Some automotive charging system designers prefer lower absorption voltages, for example 13.8 VDC, to reduce water consumption and wet Low Maintenance (Sb/Ca) starting batteries to reduce cost. Over time, this combination tends to undercharge the battery and to cause electrolyte stratification which causes the battery to gradually loose capacity due to an accumulation of lead-sulfate or premature failures. One solution is to

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periodically recharge the battery with an external charger to remove the sulfation or to increase the absorption voltage output to the battery as described by Chris Gibson on http://www.smartgauge.co.uk/alt_mod.html. Other solutions are to use an adjustable or "smart" voltage regulator, add resistance to the "sense" lead to the regulator (if equipped), or equalize the battery. Increasing the absorption voltage or equalizing will increase water consumption in wet batteries, so the electrolyte levels will need to be checked more often.

As in the Bosch Voltage Regulator example below, most voltage regulators are temperature compensated to properly charge the battery under different environmental conditions. As the ambient temperature decreases below 77° F (25° C), the charging voltage is increased to overcome the higher battery resistance. Conversely, as the ambient temperature increases above 77° F (25° C), the charging voltage is decreased. Other factors affecting the charging voltage are the alternator temperature, battery's condition, State-of-Charge (SoC), sulfation, electrical load and electrolyte purity.

VEHICLE CHARGING VOLTAGE GRAPH

[Source: Bosch]

If a battery terminal's voltage is below 13.0 volts with the engine running and the battery tests good after being recharged or if you are still having problems keeping the car battery charged, then have the charging

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system's output voltage and load tested. Also, have the car's parasitic load, the electrical load with the ignition key turned off, tested. (Please see Section 10.) A slipping alternator belt or open diode will significantly reduce the alternator's output capacity. If the output voltage is above 15.1 volts with the ambient temperature above freezing, if the battery's electrolyte levels are frequently low, "boiling", or if there is a "rotten egg" odor present around the battery, then the battery is being overcharged and the vehicle's charging system should be tested.

[back to Index]

5.2. What If My "Battery" or "Alternator" Light Is On? (Or the Gauge Is Not Showing a "Charging" Condition?)

The "Battery" or "Alternator" light is an indication that there is a significant mismatch between the voltage that the charging system is producing and the battery voltage. Some vehicles use a voltmeter or current meter to indicate if the charging system is working. The battery and charging system must work together to provide the electrical power for the vehicle and to keep the battery recharged so it can restart the engine. The most common causes, in the order of priority, are:

Low electrolyte levels

Slipping or broken alternator belt Corrosion between the battery posts and the battery

cable terminals Faulty charging system Defective battery

If the electrolyte levels, alternator belt is OK and the battery terminal connections are free from corrosion, then take your vehicle to an auto parts or battery store, and have the battery and charging system tested (highly recommended) or use the troubleshooting guide above. In the United States and Canada, some stores like Auto Zone, Sears, Wal-Mart, Pep Boys, etc., will test them for free. One of the first three simple faults in the list above has caused many a good battery to be replaced. A new battery can cause a weak alternator or starter to fail.

[back to Index]

5.3. What If I Cannot Keep My Battery Fully Charged and the Battery Tests OK?

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The vehicle's electrical load is normally satisfied first by the charging system and then any remaining power is used to recharge the battery. For example, if the total electrical load is 14 amps and the charging system is producing 35 amps at 2500 RPM, then up to 11 amps will be available for recharging the battery, which will take approximately six minutes. If the charging system is operating at say a maximum capacity of 90 amps at 5000 RPM, then the battery usually will be recharged within two minutes. Now let us assume that the engine is idling and the charging system is only capable of producing 10 amps. Four amps from the car battery are required to make up the difference to satisfy the 14 amp electrical load and the battery is being discharged further. This is why making short trips, driving in stop-and-go traffic, or during bad weather when there is a heavier electrical load, the starting battery may never get recharged and may even become "completely" discharged.

Using the example above, let's assume that an after-market, 400 watt @ 69% efficiency high-power audio system, 20 amp electric winch, or 276 watts of lights is installed that adds an additional 20 amps of load. To covert power amplifier wattage into amps, multiply the amplifier's watts by .5 to .85 (depending of the efficiency of the amplifier) and then divide by the operating voltage. To convert winch motor or lighting power (in watts) to amps, divide the watts by the operating voltage. With a total electrical load of 34 amps, at RPM below 2500, the battery will never be recharged with an 90 amp system. While the engine is running in this case, the battery must make up the deficit. The solution is to upgrade the charging system to 125% or more of the new worst-case load. In this example and based on stop-and-go driving habits, a high output charging system capable of 105 amps or more would be required to keep the battery fully charged. High alternator temperatures can further reduce the maximum output of a charging system, so cooling and sizing based on the continuous load matters. Heat kills alternators, so Bosch, for example, has water cooled models available.

For boat owners, Balmer recommends that alternator(s) be sized to 25% of the batteries' total capacity for wet batteries and 35% to 40% for AGM (Ca/Ca) and Gel Cell (Ca/Ca) VRLA batteries. Alternator belt sizing is also important. A single 3/8" belt will drive an alternator up to 80 amps, 1/2" up to 110 amps, and multiple belts for over 110 amps. Ample Power provides an excellent Troubleshooting the Alternator System guide.

[back to Index]

5.4. How Can I Test To Determine If Charging System Is Large Enough?

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A simple test to determine if the charging system is large enough is to check the battery's State-of-Charge after the surface charge has been removed. If the State-of-Charge is consistently above 95%, then the charging system is fully recharging the car battery based on your driving habits and electrical load. If is is consistently below 80%, then you will want to consider upgrading your charging system to produce more current. There are several possibilities to increase the capacity of your charging system to include changing the pulley diameters, replacing the alternator with an higher output model, adding a second charging system (for a dual battery set up), replacing the voltage regulator, etc. An auto electric or alternator rebuilding shop can assist you. If the State-of-Charge is inconsistent, the you might consider using a temperature compensated, "smart" charger with a quick disconnector to "top off" your battery. If you have a heavy electrical load while the engine is not running, install a dual or multi-battery system with the heavy load on a deep cycle battery bank. If consistently undercharged or overcharged, a lead-acid battery will lose capacity and prematurely fail

6. HOW DO I JUMP START MY VEHICLE?

Please wear glasses in the unlikely event of a car or deep cycle battery explosion and save your eyes.

If done incorrectly, jumping a dead battery can be dangerous and financially risky. These procedures are ONLY for vehicles are that are both negatively grounded and the electrical system voltages are the SAME. These procedures would also apply to using emergency jump starters. DO NOT jump a frozen battery and ALWAYS connect POSITIVE to POSITIVE and NEGATIVE (-) to the ENGINE BLOCK or FRAME away from the dead starting battery. Reverse this rule to disconnect. The American Automobile Association (AAA) estimates that of the 275 million vehicles that will traveling in the U.S. during the Summer of 2003, 7.4 million (or 2.7%) will break down. Of that number, 1.3 million (or 17.7%) will require a battery jump to start their engine. The German automobile association (ADAC) estimates that their battery related service calls has increased from 21.7% per year in 1999 to 29.9% in 2004.

In cold weather, good quality jumper cables (or booster cables) with at least eight-gauge wire are necessary to provide enough current to the disabled vehicle to start the engine. Larger diameter, smaller gauge number wire is better because there is less voltage loss. Please check the owner's manual for BOTH vehicles or jump starter BEFORE attempting to jump-start. Follow the manufacturers' procedures, for example, some vehicles should not be running during a jump-start of a disabled one. However, starting the disabled vehicle with the good vehicle running can prevent having both vehicles disabled and provides

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a higher voltage to the starting motor of the disabled vehicle. Avoid the booster cable clamps touching each other or the POSITIVE clamp touching anything but the POSITIVE (+) post of the battery, because momentarily touching the block or frame can short the battery and cause extensive and costly damage.

6.1. If below freezing, insure that the electrolyte is NOT frozen in the dead battery. If frozen, do NOT jump or boost the battery if the case is cracked or until the battery has been full thawed out, recharged, tested. When the electrolyte freezes, it expands which can damage the plates or plate separators, which can cause the plates to warp and short out. When the battery is frozen, the best solution is to substitute a fully charged battery for frozen one or tow the vehicle to a heated garage. With any completely dead battery, cell reversal can occur. Please Section   14.14 . The electrolyte in a dead battery will freeze at approximately 20°F (-6.7°C). The freezing point of a battery is determined by the SoC and the higher it is, the lower the freezing temperature. Please see the Electrolyte Freeze Points Table in Section   4.4.1 . If the battery has been sitting for several weeks and frozen, then the battery has probably sulfated as well. Please see Sections 16 and 13 for more information. If the battery has been sitting for hours or a few days then the problem is either an excessive parasitic load like leaving the headlights on or a faulty charging system. Please see Sections 10 or 9, respectively.

6.2. Without the vehicles touching, turn off all accessories, heaters and lights on both vehicles, especially electronic appliances, such as a radio or audio system and insure there is plenty of battery ventilation.

6.3. Start the vehicle with the good battery and let it run for at least two or three minutes at medium RPM to recharge it. Check the POSITIVE (+) and NEGATIVE (-) terminal markings on both batteries before proceeding.

JUMP STARTING

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[Source: BCI]

6.4. Connect the POSITIVE booster cable (or jump starter) clamp (usually RED) to the POSITIVE (+) terminal post on the dead battery [Step 1 in the diagram above]. Connect the POSITIVE clamp on the other end of the booster cable to the POSITIVE (+) terminal post on the good starting battery [Step 2]. If the POSITIVE (+) battery terminal post is not accessible, the POSITIVE connection on the starter motor solenoid from the POSITIVE (+) terminal post of the battery could be used.

6.5. Connect the NEGATIVE booster cable clamp (usually BLACK) to the NEGATIVE (-) terminal on the good battery [Step 3]. Connect the NEGATIVE booster cable (or jump starter) clamp on the other end of the jumper cable to a clean, unpainted area on the engine block or frame on the disabled vehicle [Step 4] and at least 10 to 12 inches (25 to 30 cm) away from the battery. This arrangement is used because some sparking will occur and you want to keep sparks as far away from the battery as practical in order to prevent a battery explosion.

6.6. If using jumper cables, let the good vehicle continue to run at medium RPM for five minutes or more to allow the dead battery to receive some recharge, to warm its electrolyte, and reduce the load of the dead battery. If there is a bad cable connection, do not wiggle the cable clamps

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connected to the battery terminals because sparks will occur and a battery explosion might occur. To check connections, first disconnect the NEGATIVE clamp from the engine block or frame, check the other connections, and then reconnect the engine block or frame connection last.

6.7. If using jumper cables, some vehicle manufacturers recommend that you turn off the engine of the good vehicle to protect it's charging system prior to starting the disabled vehicle. Check the owner's manual; otherwise, leave the engine running so you can avoid being stranded should you not be able to restart the good vehicle and increase the voltage to the disabled vehicle's starter motor.

6.8. If using jumper cables, start the disabled vehicle and allow it to run at high idle. If the vehicle does not start the first time, recheck the connections, wait a few minutes, and try again.

6.9. Disconnect the jumper or jump starter cables in the REVERSE order, starting with the NEGATIVE clamp on the engine block or frame of the disabled vehicle to minimize the possibility of an explosion. Allow the engine on the disabled car to run until the engine come to full operating temperature before driving and continue to run until you reach your final destination, because stopping the engine might require another jump start. Also, keep all unnecessary electrical accessories off to relieve the load on the charging system and allow it to add charge to the battery.

6.10. As soon as possible and at room temperature, fully recharge the dead battery with an external "smart" or "automatic" battery charger matched to the battery type, remove the surface charge and load test the battery and charging system to determine if any latent or permanent damage has occurred as a result of the deep discharge. This is especially important if you had a frozen battery or jump started a sealed wet Maintenance Free (Ca/Ca) battery. A vehicle's charging system is not designed to recharge a dead battery and could overheat and be damaged (bad diodes or burned stator) doing so or the battery could be undercharged and loose capacity.

In the event that the jumper or jump starter cables were REVERSED and there is no power to all or part of the vehicle, test the fusible links, fuses, circuit breakers, battery, charging system and emissions computer and, if bad, reset or replace. Their locations and values should be shown in the vehicle's Owner's Manual. If replacing the faulty parts do not repair the electrical system, having it repaired by a good auto electric repair shop is highly recommended.

6. HOW DO I JUMP START MY VEHICLE?

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Please wear glasses in the unlikely event of a car or deep cycle battery explosion and save your eyes.

If done incorrectly, jumping a dead battery can be dangerous and financially risky. These procedures are ONLY for vehicles are that are both negatively grounded and the electrical system voltages are the SAME. These procedures would also apply to using emergency jump starters. DO NOT jump a frozen battery and ALWAYS connect POSITIVE to POSITIVE and NEGATIVE (-) to the ENGINE BLOCK or FRAME away from the dead starting battery. Reverse this rule to disconnect. The American Automobile Association (AAA) estimates that of the 275 million vehicles that will traveling in the U.S. during the Summer of 2003, 7.4 million (or 2.7%) will break down. Of that number, 1.3 million (or 17.7%) will require a battery jump to start their engine. The German automobile association (ADAC) estimates that their battery related service calls has increased from 21.7% per year in 1999 to 29.9% in 2004.

In cold weather, good quality jumper cables (or booster cables) with at least eight-gauge wire are necessary to provide enough current to the disabled vehicle to start the engine. Larger diameter, smaller gauge number wire is better because there is less voltage loss. Please check the owner's manual for BOTH vehicles or jump starter BEFORE attempting to jump-start. Follow the manufacturers' procedures, for example, some vehicles should not be running during a jump-start of a disabled one. However, starting the disabled vehicle with the good vehicle running can prevent having both vehicles disabled and provides a higher voltage to the starting motor of the disabled vehicle. Avoid the booster cable clamps touching each other or the POSITIVE clamp touching anything but the POSITIVE (+) post of the battery, because momentarily touching the block or frame can short the battery and cause extensive and costly damage.

6.1. If below freezing, insure that the electrolyte is NOT frozen in the dead battery. If frozen, do NOT jump or boost the battery if the case is cracked or until the battery has been full thawed out, recharged, tested. When the electrolyte freezes, it expands which can damage the plates or plate separators, which can cause the plates to warp and short out. When the battery is frozen, the best solution is to substitute a fully charged battery for frozen one or tow the vehicle to a heated garage. With any completely dead battery, cell reversal can occur. Please Section   14.14 . The electrolyte in a dead battery will freeze at approximately 20°F (-6.7°C). The freezing point of a battery is determined by the SoC and the higher it is, the lower the freezing temperature. Please see the Electrolyte Freeze Points Table in Section   4.4.1 . If the battery has been sitting for several weeks and frozen, then the battery has probably sulfated as well. Please see Sections 16 and 13 for more information. If the battery has been sitting for hours or a few days then the problem is either an excessive parasitic load like leaving the headlights on or a faulty charging system. Please see Sections 10 or 9, respectively.

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6.2. Without the vehicles touching, turn off all accessories, heaters and lights on both vehicles, especially electronic appliances, such as a radio or audio system and insure there is plenty of battery ventilation.

6.3. Start the vehicle with the good battery and let it run for at least two or three minutes at medium RPM to recharge it. Check the POSITIVE (+) and NEGATIVE (-) terminal markings on both batteries before proceeding.

JUMP STARTING

[Source: BCI]

6.4. Connect the POSITIVE booster cable (or jump starter) clamp (usually RED) to the POSITIVE (+) terminal post on the dead battery [Step 1 in the diagram above]. Connect the POSITIVE clamp on the other end of the booster cable to the POSITIVE (+) terminal post on the good starting battery [Step 2]. If the POSITIVE (+) battery terminal post is not accessible, the POSITIVE connection on the starter motor solenoid from the POSITIVE (+) terminal post of the battery could be used.

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6.5. Connect the NEGATIVE booster cable clamp (usually BLACK) to the NEGATIVE (-) terminal on the good battery [Step 3]. Connect the NEGATIVE booster cable (or jump starter) clamp on the other end of the jumper cable to a clean, unpainted area on the engine block or frame on the disabled vehicle [Step 4] and at least 10 to 12 inches (25 to 30 cm) away from the battery. This arrangement is used because some sparking will occur and you want to keep sparks as far away from the battery as practical in order to prevent a battery explosion.

6.6. If using jumper cables, let the good vehicle continue to run at medium RPM for five minutes or more to allow the dead battery to receive some recharge, to warm its electrolyte, and reduce the load of the dead battery. If there is a bad cable connection, do not wiggle the cable clamps connected to the battery terminals because sparks will occur and a battery explosion might occur. To check connections, first disconnect the NEGATIVE clamp from the engine block or frame, check the other connections, and then reconnect the engine block or frame connection last.

6.7. If using jumper cables, some vehicle manufacturers recommend that you turn off the engine of the good vehicle to protect it's charging system prior to starting the disabled vehicle. Check the owner's manual; otherwise, leave the engine running so you can avoid being stranded should you not be able to restart the good vehicle and increase the voltage to the disabled vehicle's starter motor.

6.8. If using jumper cables, start the disabled vehicle and allow it to run at high idle. If the vehicle does not start the first time, recheck the connections, wait a few minutes, and try again.

6.9. Disconnect the jumper or jump starter cables in the REVERSE order, starting with the NEGATIVE clamp on the engine block or frame of the disabled vehicle to minimize the possibility of an explosion. Allow the engine on the disabled car to run until the engine come to full operating temperature before driving and continue to run until you reach your final destination, because stopping the engine might require another jump start. Also, keep all unnecessary electrical accessories off to relieve the load on the charging system and allow it to add charge to the battery.

6.10. As soon as possible and at room temperature, fully recharge the dead battery with an external "smart" or "automatic" battery charger matched to the battery type, remove the surface charge and load test the battery and charging system to determine if any latent or permanent damage has occurred as a result of the deep discharge. This is especially important if you had a frozen battery or jump started a sealed wet Maintenance Free (Ca/Ca) battery. A vehicle's charging system is not designed to recharge a

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dead battery and could overheat and be damaged (bad diodes or burned stator) doing so or the battery could be undercharged and loose capacity.

In the event that the jumper or jump starter cables were REVERSED and there is no power to all or part of the vehicle, test the fusible links, fuses, circuit breakers, battery, charging system and emissions computer and, if bad, reset or replace. Their locations and values should be shown in the vehicle's Owner's Manual. If replacing the faulty parts do not repair the electrical system, having it repaired by a good auto electric repair shop is highly recommended.

7. WHAT DO I LOOK FOR IN BUYING A NEW BATTERY?

INDEX:

7.1. Battery Types

7.1.1. Wet Standard (Sb/Sb)

7.1.2. Wet Low Maintenance (Sb/Ca)

7.1.3. Wet "Maintenance Free" (Ca/Ca)

7.1.4. AGM [Absorbed Glass Mat] (Ca/Ca) VRLA

7.1.5. Spiral Wound AGM (Absorbed Glass Mat) VRLA

7.1.6. Wet Marine/Recreational Vehicle (RV)

7.1.7. Gel Cell (Ca/Ca) VRLA

7.1.8. What Are the Differences Between Car, Marine/RV Dual Purpose and Deep Cycle Batteries?

7.1.9. What Are Dual or Multi-battery Systems?

7.1.10. Can Deep Cycle Batteries Used As Starting Batteries?

7.2. CCA (Cold Cranking Amp) Performance

CCA vs. Temperature Diagram

7.3. Reserve Capacity (RC) or Amp Hour (AH) Capacity

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Peukert Effect

7.3.1. Is Capacity Effected By Temperature?

AH Capacity vs. Temperature Graph

7.3.2. How Do I Increase Battery Capacity?

Battery Wiring Diagrams

7.3.3. Which is Better, Two 6-volt Batteries in Series or Two 12-volt Batteries in Parallel?

7.3.4. How Do I Increase the Voltage?

7.3.5. How Can I Reduce the Voltage?

7.3.6. Which Weighs More--One 12-volt or Two 6-volt Batteries?

7.3.7. Can I Mix Non-Identical or Old and New Batteries?

7.4. Size

7.5. Terminals and Lugs

7.6. Freshness

7.7. Warranty

7.8. Buying Tips

7.9. How Do I Size The Components For Backup AC Power?

7.10. How Do I Size Deep Cycle Batteries or Battery Banks?

Car battery buying strategy for use in Canada, for example, is different than in the hotter climates found in South Texas. In cold climates, higher CCA (Cold Cranking Amp) performance ratings are more important. In a hot climate, higher RC (Reserve Capacity) or AH (Ampere Hour) capacity ratings are more important than CCA; however, the cranking amp performance sizing should be based on the coldest climate the engine is started in. Do NOT buy a new battery until it is needed because it will sulfate sitting in storage and you will lose capacity and performance. Below is an example of a wet Low Maintenance car battery life expectancy in the United States from Interstate Batteries:

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[Source: Interstate Batteries]

7.1. Battery Types

The two most common categories of car (including motorcycle and other power sports starting) and deep cycle batteries are Wet (also known as "flooded", "liquid electrolyte", "vented", or "VLA" cell) and Valve Regulated Lead-Acid (VRLA). Within the wet category, the three most common battery types in order of use are Low Maintenance, sealed "Maintenance Free", and Standard, which are defined in more detail below. In the VRLA category, there are AGM or Absorbed Glass Mat, spiral wound AGM, and Gel Cell lead-acid batteries. The one additional sub-category for smaller (typically below 50 AH) deep cycle batteries is SLA (Sealed Lead-Acid) using AGM or Gel Cell VRLA construction. In 2004, approximately 30% of all SLA batteries are produced in China. All VRLA batteries are sealed with a safety pressure relief valve or plug in case of excessive gas pressure build up due to overcharging or overheating.

When selecting a battery type, it is extremely important that you select a battery that will MATCH the voltage outputs of your charging system and application. The easiest way to accomplish this is to replace your battery with the same or compatible type of battery that originally was installed in your vehicle or appliance. If you change your replacement battery to another battery type, you might have to adjust the charging voltage to prevent undercharging or overcharging that could damage or reduce the service life of your

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new battery. For example, replacing an Original Equipment Manufacturer (OEM) wet sealed "Maintenance Free" with a wet non-sealed Low Maintenance battery (with filler caps) might cause the Low-Maintenance battery to be slightly overcharged and consume more water. If you charge a wet "Maintenance Free" battery with a charging system or charger designed for a wet Low Maintenance battery (with filler caps), you could undercharge the wet "Maintenance Free" battery. Replacing any other non-Gel Cell type of battery with a Gel Cell VRLA battery could overcharge it. If in doubt, replace with an AGM VRLA or spiral wound AGM VRLA battery because they have a wider charging voltage range. Ventilation is required for all lead-acid batteries and good ventilation is mandatory for wet batteries to dissipate the explosive gasses produced during the absorption or equalization charge stages.

Deep cycle batteries are broadly divided into motive, stationary and solar applications. Motive applications are where the battery is discharged in operations that will consume between 20% and 80% of the battery's capacity and then recharged (which is considered to be one cycle). Some examples of motive (also known as "cycling", "leisure" or "traction") applications are for batteries used in recreational vehicles (RV), motor homes, caravans, trailers, boats, wheelchairs, golf carts, solar, floor sweepers, folk lift trucks and other electric vehicles (EV) and typically have between 200-500 cycles per year. Stationary (also known as "float", "reserve", "backup" or "standby") applications are where stationary batteries is used to provide backup or standby power during loss of the primary source of power such as uninterruptible power systems (UPS), emergency lighting systems, security systems, telecommunications systems, etc., and typically have 2-12 cycles per year. If keep below 80 degrees F (26.7 degrees C), stationary batteries have longer service lives than motive batteries due to thicker plates and being used less. They also cost more than motive batteries. The chargers for stationary deep cycle batteries are different from car and motive deep cycle batteries and normally have three stages--bulk, float and equalize. Please see Section 9.1 for more information on charging and charging stages. Solar or photo voltaic (PV) batteries are special purpose and used solar applications.

Non-sealed wet Standard, wet Low-Maintenance, AGM or Gel Cell VRLA batteries with pasted, tubular or Manchester ("Manchex") positive plates or Spiral Wound AGM VRLA batteries are recommended for motive deep cycle applications. Non-sealed wet Standard, wet Low-Maintenance, wet "Maintenance Free" batteries with pasted or solid (Planté) positive plates are recommended for

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stationary applications. For more information about deep cycle batteries, please see Allan Tarvid's article Fishing for the Right Battery, Wind & Sun's Ultimate Deep Cycle Battery FAQ and Zen and the Art of Choosing a Deep Cycle Battery.

Wet deep cycle batteries, such as marine/RV, leisure and some golf cart, that use pasted positive plates are less expensive to manufacturer and have fewer life cycles and shorter service lives at 50% average Depth-of-Discharge (DoD) level than the deep cycle batteries with solid (Planté), tubular or Manchester (or "Manchex") positive plates. They also have significantly fewer life cycles at the 80% average DoD level. The major disadvantage of AGM or Gel Cell VRLA deep cycle batteries are their high initial cost (up to three times over the cost of a wet Standard batteries), but arguably can have an overall lower total cost of ownership due to a longer service life, no "watering" and other labor costs, and faster recharging. The total cost of ownership should be considered when buying deep cycle batteries. There is a cost comparison for some popular wet solar deep cycle batteries on THE SOLAR BiZ Web site at http://www.thesolar.biz/Cost_Table_batteries.htm.

[back to Index]

7.1.1. Wet Standard (Sb/Sb)

Wet Standard or "Conventional" (Sb/Sb) non-sealed lead-acid batteries (with filler caps) have Lead with Antimony (Sb) alloy in the positive and Lead with Antimony (Sb) alloy in the negative plates and have been commercially available for almost 100 years. In 1915, the Willard Storage Battery Company introduced sealed hard rubber cases that made car batteries practical. Examples are wet deep cycle batteries from Surrette/Rolls, Trojan, U.S. Battery, etc. They have a:

Lower initial cost than other types the same capacity

Tolerance for a wide range of charging current (to 25% of the battery's capacity) and voltage

More forgiving when accidentally overcharged Long service life (if properly maintained) Increased water consumption and production of gas

requiring more ventilation Highest self-discharge rate (typically 1% per day and

on hot days, up to 2%)

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Charging losses of 15%-20% and maximum continuous discharge rate of 25% of their capacity

For these reasons, they have almost been completely replaced by wet Low Maintenance (Ca/Sb) batteries for high temperature underhood starting applications, but are still used for many Marine/RV, solar, golf cart, etc. deep cycle applications. Wet Standard (Sb/Sb) batteries are generally the least expensive lead-acid batteries per amp hour of capacity.

[back to Index]

7.1.2. Wet Low Maintenance (Sb/Ca)

The wet (or "flooded" cell), non-sealed Low Maintenance batteries (with filler caps) have Lead with Antimony (Sb) alloy in the positive and Lead with Calcium (Ca) alloy in the negative dual alloy or hybrid plate formulations. They have most of the same characteristics as a wet Standard (Sb/Sb) batteries, except they can better handle the higher underhood heat when used in starting applications. Some battery manufacturers, such as Johnson Controls, build "North" and "South" car battery versions to make up for the differences in cold and hot climates. Some also construct special car batteries that have a higher tolerance to heat by changing plate or connecting strap formulations or providing for more electrolyte. For off highway applications in power sports (including motorcycles), trucks, Recreational Vehicles (RVs), motor homes (or caravans), 4x4s, vans or SUVs (Sport Utility Vehicles), some battery manufacturers build "high vibration", "heavy duty", "commercial", or "Marine/RV" battery versions designed to reduce the effects of moderate vibration. A wet Low Maintenance (Sb/Ca) car or deep cycle battery will typically cost a little more than a similar sized wet Standard (Sb/Sb) battery and is the most common lead-acid battery plate chemistry in use today.

[back to Index]

7.1.3. Wet "Maintenance Free" (Ca/Ca)

Wet "Maintenance Free" batteries have a Lead with Calcium (Ca) alloy in the positive and Lead with Calcium (Ca) alloy in

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the negative plate chemistry or formulation, for example, Johnson Controls [formally Delphi], General Motor's ACDelco, or East Penn. They are available in non-sealed sealed (with removable filler caps) and sealed (with non-removable filler caps) versions. The non-sealed versions are recommended for use in hot climates, so lost water can be replaced. The advantages and disadvantages of wet "Maintenance Free" (Ca/Ca) car and deep cycle batteries over wet Low Maintenance (Sb/Ca) are:

Less preventive maintenance due to less water loss

More forgiving when accidentally overcharged Require a slightly higher (.45 VDC) absorption

charging voltage Reduced terminal corrosion and ventilation Smaller self-discharge rate Less risk to consumers because there is less to

service

However, the versions with "GM" side terminals are more prone to terminal seal leakage due to over-tightening, incorrect terminal bolt length, or vibration from short battery cables. Please see Section 7.5 for more information on terminal types. They are also more susceptible to deep discharge ("dead" or "flat" battery) failures due to increased shedding of active plate material and development of a barrier layer between the active plate material and the grid metal. If a wet "Maintenance Free" (Ca/Ca) battery is sealed, distilled water can not be added when required. For that reason, in hot climates, using non-sealed wet batteries (with filler caps), so distilled water can be added, is highly encouraged. For passenger compartment or trunk battery locations, using a sealed AGM (Ca/Ca) VRLA battery is recommended. Wet "Maintenance Free" (Ca/Ca) batteries are generally little more expensive than wet Low Maintenance (Sb/Ca) batteries.

[back to Index]

7.1.4. AGM [Absorbed Glass Mat] (Ca/Ca) VRLA

Sealed Absorbed Glass Mat (Ca/Ca) VRLA car and deep cycle batteries (also know as "starved electrolyte" or "dry") have a very fine fiber Boron-Silicate glass mat between their

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flat Lead with Calcium alloy in the positive and Lead with Calcium alloy in the negative plates. The AGM battery was invented in 1980 and first used in military aircraft in 1985. They have all of the advantages of the "Maintenance Free" (Ca/Ca) batteries plus:

Much safer then wet batteries (due the hydrogen gas recombination during charging)

Do not require water Lower self-discharge rate (typically 1%-2% per

month) Longer service life Higher resistance to vibration Lower deep discharge failure Less forgiving when accidentally overcharged Higher bulk charge acceptance rate (which means up

to a 15% shorter recharge time and reduced cost) Lower tolerance for heat Do not require special hazardous shipping Can be used in saltwater applications Spill proof and can be mounted in virtually any

position (because they are sealed) Can be used inside a semi-enclosed area, like the

passenger compartment or trunk Greater terminal corrosion resistance Less charging voltage tolerance Not subject to sulfation from electrolyte stratification

or water loss Charging losses of 4% and maximum continuous

discharge rate 33% of their capacity

Relocating the vehicle's starting battery to the passenger compartment or trunk is becoming more popular because vehicle manufacturers want to extend their "bumper-to-bumper" warranty periods, to avoid underhood temperature extremes, to provide more weight in the rear, or to save underhood space. Use a vented wet battery or GRT (Gas Recombinant Technology) AGM (Ca/Ca) or Gel Cell (Ca/Ca) VRLA battery. GRT simply means that 90% or more of the gasses are recombined back into water during recharging and contained within each cell and special venting is not required. AGM (Ca/Ca) VRLA batteries are more expensive than wet "Maintenance Free" (Ca/Ca) batteries. Some AGM (Ca/Ca) batteries, for example Concorde, can be equalized. They will accept all the power that a charging system will produce. This means if you are using an alternator sized at

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25% (or less) of the capacity of a deep cycle battery bank, it is possible to overheat an air cooled alternator and burn it up during a long bulk charging phase. For large capacity deep cycle battery banks, using a high output alternator, voltage regulator with an alternator temperature sensor or water cooled alternator is highly recommended. A thermally protected alternator should not exceed 33% of the capacity of the battery bank being charged.

You can expect AGM (Ca/Ca) VRLA starting batteries to the $80 to $100 range as more competition occurs. Examples of sealed AGM (Ca/Ca) VRLA batteries are Concorde's Lifeline, EnerSys' Odyssey, or East Penn. An AGM (Ca/Ca) battery can normally replace a wet Low Maintenance (Sb/Ca) or wet "Maintenance Free" (Ca/Ca) battery, but a wet Low Maintenance (Sb/Ca) battery normally cannot replace an AGM (Ca/Ca) VRLA battery without adjusting the charging voltages. 36-volt AGM (Ca/Ca) starting batteries with 14/42-volt dual or 42-volt electrical systems offered by some of the premium car manufacturers starting in the 2003 model year. In the near term, expect to see more sealed AGM (Ca/Ca) batteries replacing wet Low Maintenance (Sb/Ca) and wet sealed "Maintenance Free" (Ca/Ca) lead-acid batteries. Nickel-Metal-Hydride (NiHM) and Lithium Ion (LiIon) batteries and Super Capacitors will used in hybrid and electric vehicle automotive applications, which might eventually be replaced by fuel cells in the next 10-20 years. Please see Collyn Rivers' article Absorbed Glass Mat Batteries for more information on AGM batteries.

[back to Index]

7.1.5. Spiral Wound AGM (Absorbed Glass Mat)VRLA

For excessive vibration applications, in off-road operation, or extreme conditions, it is best to use a spiral wound AGM VRLA (Valve Regulated Lead-Acid) car or deep cycle battery because there is no shedding of active plate material since the plates are immobilized. In addition, they also use GRT (Gas Recombinant Technology) and have all of the characteristics of the AGM (Ca/Ca) VRLA batteries with Lead with Calcium alloy in the positive and Lead with Calcium alloy in the spiral wound plates plus:

Withstand up to 15 times more vibration

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Up to twice the number of cycles than a wet lead-acid battery

Smaller Recharges faster reducing charging cost Wider absorption and float charging voltage variance Withstand heat better Charging losses of 4% and maximum continuous

discharge rate 33% of their capacity

Examples of spiral wound AGM VRLA batteries are Johnson Controls' Optima, Exide's Select Orbital or Maxxima, EnerSys' Cyclon, BLS, or ToPin. Typically spiral wound AGM car batteries cost between $90 and $150 and deep cycle versions cost more.

SPIRAL WOUND AGM BATTERY

[Source: Optima]

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7.1.6. Wet Marine/Recreational Vehicle (RV)

Wet marine/RV batteries are available in three different versions--starting, "dual purpose", and deep cycle. The wet "starting" marine/RV battery is basically a wet car (or starting) battery with carrying handles and stud or combination terminals and designed for high current and shallow discharges (up to 5% Depth-of-Discharge). It maybe ruggedized to be more resistant to vibration and shock than

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an automobile battery. The battery's construction, separator thickness and material, plate thickness and plate composition will all determine a battery's ability to withstand vibration. Securing the battery to reduce the vibration will increase it's service life.

The wet "dual purpose" marine/RV battery is a compromise between a starting and deep cycle battery that is specially designed for high vibration in marine/RV applications. It is generally are more expensive than a starting battery. The "deep cycle" marine/RV battery is designed for deep discharge applications, such as a running a trolling motor. Marine "starting", "dual purpose", or "deep cycle" batteries can have wet Standard (Sb/Sb), wet Low Maintenance (Sb/Ca), or wet "Maintenance Free" (Ca/Ca) plate formulations. Please beware of marine/RV batteries that are cheap, because they are often car batteries with handles and stud or combination terminals. A marine/RV "deep cycle" or "dual purpose" battery will work as a starting battery if it can produce enough current to start the engine. Good ventilation is required for all wet (or "flooded") batteries to dissipate the gasses produced during charging. For saltwater applications, use ONLY sealed AGM (Ca/Ca) or Gel Cell (Ca/Ca) VRLA batteries to prevent the formation of DEADLY chlorine gas if battery electrolyte is mixed with saltwater.

[back to Index]

7.1.7. Gel Cell (Ca/Ca) VRLA

Sealed Gel Cell (Ca/Ca) VRLA (Valve Regulated Lead-Acid) deep cycle batteries also use GRT (Gas Recombinant Technology) and were invented in 1934 by Otto Jache and commercially introduced by Sonnenschein in 1957. They use a thickening agent like fumed silica gel to immobilize the electrolyte instead of a liquid electrolyte like wet batteries. Gel Cell batteries have a lot of the same advantages and disadvantages of AGM (Ca/Ca) VRLA batteries and use Lead with Calcium (Ca) alloy positive and Lead with Calcium (Ca) alloy negative plate formulations. When comparing Gel Cell (Ca/Ca) to AGM (Ca/Ca) and Spiral Wound AGM batteries, Gel Cells will typically:

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Have greater ability to withstand a deep discharge, but not temperatures over 100°F (37.8° C) because of the possibility of "thermal runaway"

Need a 10 to 15 cycle preconditioning or "break-in" period

Supply less Cold Cranking Amps Have 80% of the capacity of a similar sized AGM

(Ca/Ca) battery and physically larger Require longer recharging times and lower currents More forgiving when accidentally overcharged Are intolerant of incorrect charging voltages which

require special gel cell chargers or gel cell settings Produce lower capacity in cold temperatures Provide up to 20% more life cycles than AGM VRLA

batteries Costs more because more expensive to manufacture Can loose capacity due to voids between the plates

when overcharged Sustain charging losses of 4% and maximum

continuous discharge rate 25% of their capacity

The ideal ambient temperature for a Gel Cell (Ca/Ca) battery is 72° F (22.2° C). Examples of Gel (Ca/Ca) batteries are Sonnenschein, East Penn, MK, Exide, etc.

For some considerations of replacing flooded batteries with Gel Cell (Ca/Ca) or AGM (Ca/Ca) VRLA batteries, please read David Eidell's IMPORTANT NOTE ABOUT THE SUITABILITY OF ABSORPTIVE GLASS MAT (AGM) AND GELLED ELECTROLYTE BATTERIES IN RV'S or Collyn Rivers' ABSORBED GLASS MAT BATTERIES. For a more detailed comparison, read an article written by Constian von Wentzel, Comparing Marine Battery Technologies.

[back to Index]

7.1.8. What Are the Differences Between Car, Marine/RV "Dual Purpose", and Deep Cycle Batteries?

Car and marine/RV starting batteries are specially designed with thinner (.04 inch or 1.02 mm) and more porous plates for a greater surface area to order produce the high current required to start an engine. They are engineered for up to 5,000 shallow (to 3% Depth-of-Discharge) discharges, which

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is over four engine starts per day. Starting batteries should NOT be discharged below 10% Depth-of-Discharge (DoD). They use sponge lead and expanded metal grid paste plates rather than solid lead plates. Marine/RV "dual purpose" batteries are a compromise between a car and deep cycle battery and are designed for starting and prolonged discharges at lower amperage that typically consumes between 20% and 50% of the battery's capacity. The plates are thicker that in starting batteries, but thinner than in deep cycle batteries. Motive and stationary deep cycle batteries have much thicker (up to .25 inch or 6.35 mm) plates, thicker grids, more lead, and weight more than car batteries of the same size. They also have a slightly higher Specific Gravity and are normally discharged between 20% and 80% Depth-of-Discharge at a lower amperage. Deep cycle batteries will typically outlast two to ten car batteries in a deep cycle application.

[back to Index]

7.1.9. What Are Dual or Multi-battery Systems?

For special high electrical load requirements, such as an emergency vehicles, RVs, motor homes, caravans, boats, or vehicles with snow plows, electric winches, high power audio or lighting systems, etc., both car and deep cycle batteries are often used. A car battery is normally used to start the engine and motive deep cycle (or leisure) batteries that are the same battery type (plate chemistry) as the car battery are used to power the electrical accessories. The batteries are usually connected to dual charging systems or a Schottky diode isolator (or combiner), dual output alternator, isolation relay or A/B switch to keep the starting battery from becoming discharged when using the auxiliary deep cycle batteries. When the charging system is running, the batteries are automatically recharged (except with the manual relay or A/B switch) with most of the current flowing to the battery with the highest Depth-of-Discharge. Isolator sizing is important and should be larger than the combined current sources on each side of the isolator. For example, if a diode isolator is used with a 40 amp "shore" power battery charger and a 100 amp alternator, then the diode rating should be at least 140 amps. If a relay or A/B switch is used and the charger is 100 amps, but there is a load of 300 amps, then the isolator need to be rated at the larger of the two or 300

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amps or more. The wiring with fuses also needs to be rated to carry at least this much current with a 5% or less voltage drop at full current.

Ralph Scheidler at Sure Power has written an excellent, easy to understand, free e-booklet, Introduction to Batteries and Charging Systems, about multi-battery applications. It is available online at http://www.surepower.com/pdf/ebr_int.pdf. A common deep cycle application in recreational vehicles is using a DC to AC inverter, which is used to convert 12 volts DC to 120 (or 240) VAC power. It takes between 12 and 14 amps of 12-volt DC power to make one amp (or 120 watts) of 120 VAC power (or one-half amp or 120 watts of 240 VAC power), so deep cycle batteries or vehicle charging systems should be used to power inverters and NOT starting batteries. Some multi-battery systems can get extremely complex.

Some of the following risks are undertaken when a discharged deep cycle battery (or bank) is connected in parallel to the starting battery without using a diode isolator:

If a discharged deep cycle battery (or bank) is connected to a charged starting battery in parallel, a large current could flow from the starting battery to the deep cycle battery in an attempt to equalize the voltage. Overtime, deeply discharging the starting battery could prematurely kill it. This can discharge the starting battery to the point that the engine can not be started.

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If the wiring or contacts of the isolation relay or switch are not heavy enough to carry the current, damage could occur.

If 4% or more concentration of hydrogen is present, an explosion could occur due to the arc created by the relay or switch closure.

If the charging system has insufficient capacity, a large deep cycle battery (or bank), especially a AGM (Ca/Ca) VRLA, could accept all the output of the charging system and overheat the alternator causing it to fail or not fully recharge the starting battery.

Either the deep cycle battery (or bank) is undercharged or the starting battery will be overcharged.

Diode isolation systems, unless voltage compensated, lose between .6 and 1.6 volts across each diode. There is also loss in wring that will reduce the charging voltage to the battery. Regardless of what isolation method is used, apply the battery manufacturer's temperature compensated charging voltages directly across the respective battery terminals to optimize the battery's capacity and overall service life. This is especially important when mixing battery types and can be accomplished in several different ways depending on the charging system. For example, if the voltage regulator is equipped with a sense wire, it can be connected to the output of the diode isolator or positive battery terminal or the internal voltage regulator can be replaced with an adjustable or a "smart" voltage regulator. Individual battery or battery bank voltage regulators can be used downstream of the isolator. If the voltages are not correct, then battery under or overcharging can occur and cause premature failures. If the deep cycle battery bank is located within a living or passenger area, using AGM (Ca/Ca) or Gel Cell (Ca/Ca) VRLA batteries is highly recommended for safety reasons.

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7.1.10. Can Deep Cycle Batteries Used As Starting Batteries?

Some things to consider in using a motive deep cycle (or Marine/RV Dual Purpose) battery as a starting battery are:

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Is it the same battery type as your OEM starting battery? This is so that your vehicle's charging system will keep it fully charged. Typically, deep cycle batteries require higher charging voltages than car batteries. Please see Section   7.1 for more on battery types and Section   5.4 and testing.

Will the battery produce enough current to start the engine in the coldest temperatures that you start your engine in?

Will it fit, will the lugs (terminals) match the battery posts and will the battery cables be long enough to connect to the correct battery posts?

Can you afford to get stuck some cold morning until you can jump start your vehicle if it does not have the capacity to start you engine?

Is the battery fresh and in good condition? Depending on the temperature and battery type, a battery has been sitting around for weeks or months without a charge has probably sulfated. If the battery has sulfated, please see Section   16 .

If the answer to these questions is yes, then it should work. However, it might crank the engine slower or not last as long as a starting battery for this application, due of the high under hood temperatures and shallower discharges. There have been other examples where a wet motive deep cycle batteries have lasted over ten years. Fully recharge the deep cycle battery with an external charger first and have it tested at an auto parts or battery store. If good, then try it and monitor the SoC and electrolyte levels for the the first few months for proper charging. If the State-of-Charge is continuously low, the battery is being undercharged and sulfate will gradually build up, thus reducing the capacity of the battery and causing it to prematurely fail. If it is using a lot of water, then it is being overcharged and can prematurely fail.

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7.2. CCA (Cold Cranking Amp) Performance

If the battery is to used in a starting application, Cold Cranking Amp (CCA) performance is the second most important consideration; otherwise, for deep cycle applications, please skip this section and

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go to Section   7.3. Reserve Capacity (RC) or Amp Hour (AH) Capacity. The battery's CCA performance rating should meet (or just exceed) the vehicle manufacturer's recommendation or is best suited for the coldest temperatures encountered in your climate. BCI's definition of CCA is the discharge load measured in amps that a new, fully charged battery, operating at 0° F (-17.8° C), can deliver for 30 seconds while maintaining the voltage above 7.2 volts. Car and Marine Starting batteries are sometimes advertised by their CA (Cranking Performance Amps) measured at 32° F (0° C), MCA (Marine Cranking Amps) measured at 32° F (0° C), or HCA (Hot Cranking Amps) measured at 80° F (26.7° C). These measurements are not the same as CCA. Do not be misled by the higher CA, MCA or HCA ratings. To convert CA or MCA to CCA, multiply the CA or MCA by 0.8. To convert HCA to CCA, multiply HCA by 0.69. The British and International Electrotechnical Commision's definition of CCA are cranking for 180 seconds and down to 8.4 volts at 0° F (-17.8° C) and for 60 seconds and down to 8.4 volts at 0° F, (-17.8° C), respectively.

To start a four cylinder gasoline engine, you will need approximately 600-700 CCA; six cylinder gasoline engine, 700-800 CCA; eight cylinder gasoline engine, 750-850 CCA; three cylinder diesel engine, 600-700 CCA; four cylinder diesel engine, 700-800 CCA; and eight cylinder diesel engine, 800-1200 CCA. Bruce Bowling and Al Grippo have written a very handy Battery Cold-Cranking Amp Estimation calculator which can be found at http://www.bgsoflex.com/cca.html. To convert CCA, a SAE (Society of Automotive Engineers) standard, to an EN (now known as ETN), IEC, DIN or JIS standard, please refer to the Conversion Table at www.cadex.com/_downloads/_support/SpectroQuickRefGuide.pdf from Cadex or http://web.archive.org/web/20050517213320/http://www.midtronics.com/manuals/power_sensor105_manual.pdf from Midtronics.

In hot climates, buying car or marine starting batteries with double or triple your vehicle's cold cranking amp requirements is a waste of money because the extra amps will not be used. A starter motor will only demand what it needs to operate. However, in extremely cold climates a higher CCA rating is better, due to increased power required to crank a sluggish engine and the inefficiency of a cold car battery. As car batteries age, they are also less capable of producing as much CCA as when they were new. According to BCI (Battery Council International), diesel engines require 220% to 300% more current than their gasoline counterparts and winter starting requires 140% to 170% more current than during summer. These increased requirements are accounted for in the OEM

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(Original Equipment Manufacturer) CCA performance recommendations .

CCA PERFORMANCE vs. TEMPERATURE

[Source: Exide]

If more CCA performance is required, two identical 12-volt starting batteries can be connected in parallel or two identical larger CCA 6-volt starting batteries can be connected in series. Please refer to the diagrams in Section 7.3 below for more information about connecting batteries in parallel or series. If you connect two 12-volt batteries in parallel and they are identical in type, age and capacity, you can potentially double your original CCA performance. If you connect two in series that are not the same type or capacity, the battery (or cell) with the lowest capacity will overcharge or over discharge.

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7.3. Reserve Capacity (RC) or Amp Hour (AH) Capacity

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Making a simple analogy between a water tank and a battery, the level in the tank will determine the water pressure (battery's voltage), but the diameter of the tank is going to determine the total volume of water (battery's Reserve Capacity or amp hour capacity). The size of the outlet will limit the discharge rate.

For car batteries, an equally important consideration to CCA is the Reserve Capacity (RC) or Amp Hour (AH) endurance ratings because of the effects of increased parasitic (ignition key off) loads while long term parking, power demands during short trips and emergencies. Endurance is defined by Eurobat as the actual combination of the energy content stored in a battery and the rate which the battery is discharged over the life time. RC is the number of minutes a fully charged battery at 80° F (26.7° C) can be discharged at a constant 25 amps until the voltage falls below 10.5 volts. European and Asian starting and deep cycle batteries are usually rated in Amp Hours (AH). To convert RC to AH (or AH to RC), check the battery manufacturer's capacity specifications. More RC (or AH) is better in every case. In a hot climate, if your car has a 360 OEM cold cranking amps requirement, then a 400 CCA rated battery with 120 minutes of RC and more electrolyte for cooling would be more desirable than one with 600 CCA with 90 minutes of RC. There is also a relationship between the weight of the battery and the amount of RC (or AH). The heavier the battery, the more lead is has and potentially a longer service life.

For deep cycle batteries, important considerations are will the Ampere-Hour (AH) rating meet or exceed the requirements based on your application? Peukert Effect? and how much weight you can carry? Most deep cycle batteries are normally rated in number of hours it take to discharge a fully charged battery to 10.5 volts in 20 hours at 80° F (26.7° C), denoted as "C/20". Discharge rates of 100 hours (C/100), 10 hours (C/10), 8 hours (C/8) or 6 hours (C/6) are also common ratings. When comparing amp hour capacities of deep cycle batteries, use the same discharge rating periods which can be obtained form the battery manufacturer. For example due to the Peukert Effect, the same wet deep cycle battery with the amp hour capacity of 240 discharged over 20 hours could have a capacity of 176 amp hours when discharged over six hours or 115 amp hours when discharged in one hour. Within a BCI Group Size, the battery with higher AH (or RC) will tend to larger in physical size, have longer service lives and weigh more because of thicker plates and more lead than car batteries.

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PEUKERT EFFECT

In 1897, W. Peukert determined that the higher the discharge rate (or fewer hours the battery is fully discharged in), the lower the capacity due to the Peukert Effect or "the shrinking battery effect" and to the internal resistance of the battery. Good examples of the Peukert Effect on deep cycle battery capacities at various discharge rates can be found at http://www.usbattery.com/ on their capacity specifications page. The actual formula is T=C/IN where N is the Peukert Number used for the specific battery to more accurately calculate the discharge time. For a detailed explanation of the calculation, please see Steve Gibson's article, An in depth analysis of the math behind Peukert's Equation (Peukert's Law). The Peukert Number generally is in a range of 1.05 to 1.4, with 1.05 the best performing battery due to less internal resistance. A Peukert Number calculator and some specific examples of batteries can be found on Eve's Battery Page at http://www.geocities.com/CapeCanaveral/Lab/8679/battery.html.The effects are shown in Constantin von Wentzel's graph below. A good analogy on the Peukert Effect and be found at Ample Power on http://www.amplepower.com/pwrnews/beer/. Another Peukert calculator is included on http://home.hetnet.nl/~marcellebarion/epeukert.html.

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[Source: How Lead-Acid Batteries Work]

Normally the best buy will be the heaviest battery that best suites your application, physical size requirements and that has the lowest cost (including maintenance) for the total amount of power it will produce over it's service life. Larger is better!

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7.3.1. Is Capacity Effected By Temperature?

Temperature matters! The following graph from Concorde shows the effects of temperature on the amp hour capacity on their AGM (Ca/Ca) battery:

PERCENT CAPACITY vs. TEMPERATURE

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[Source: Concorde]

7.3.2. How Do I Increase Battery Capacity?

If more amp hours (AH) or Reserve Capacity (RC) are required, there are normally three ways to accomplish this:

7.3.2.1. Two (or more) 12-volt batteries can be connected in parallel, should be identical and connected exactly as shown in the diagram below for best results. If you connect two 12-volt batteries in parallel and they are identical in type, age and capacity, you can more than double your original capacity due to the Peukert Effect. If you connect two or more batteries (or battery banks) in parallel that are not the same type or capacity, proper charging can become more difficult. Using a properly sized "smart" charger is highly recommended. To better balance the voltage, please take special note of the connections from the POSITIVE (+) battery terminals to a single positive (+) distribution point and the connections from

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the NEGATIVE (-) battery terminals to a single NEGATIVE (-) distribution point. All of the interconnecting leads between the battery terminals and distribution points need to be exactly the same wire size and length so the voltage will be the same. The number of batteries (or strings of batteries) in parallel should be limited to four. For more information on connecting batteries in parallel, please see Chris Gibson's excellent article How to correctly interconnect multiple batteries to form one larger bank. Chris' article goes into detail on why incorrectly connecting batteries in parallel will cause loss of capacity resulting in premature battery failures.

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12-Volt Batteries In Parallel

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7.3.2.2. Two identical larger capacity six-volt batteries can be connected in series by connecting the NEGATIVE (-) terminal of Battery One to the POSITIVE (+) terminal of Battery Two. Do not mix non-identical battery types, battery manufacturers or capacity in series because the battery (or cell) with the lowest capacity will overcharge or over discharge. Batteries in series are much easier to correctly charge, offer higher reliability due to few number of cells, but are limited to the lowest capacity battery (or cell) in the series.

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Batteries In Series

7.3.2.3. Two identical larger capacity six-volt batteries can be connected in series by connecting the NEGATIVE (-) terminal of Battery One to the POSITIVE (+) terminal of Battery Two to make a "12-volt battery". Two (or more) "12-volt batteries" can be connected in parallel. The combination is referred to as a series-parallel bank. Please see the recommendations for connecting batteries (or battery banks) in parallel in Section 7.3.2.1 above.

6-Volt Batteries In Series-Parallel

When connected as exactly shown in the above diagrams, the batteries will better discharge and charge equally and have a longer service life. Between the battery terminals or battery terminals and distribution points, the cables should be an equal length, same wire size, as short as possible and sized large enough to prevent significant voltage drop of 0.075 volts (75 millivolts) per 100 amps or less in the cables and connectors. Battery cables to the charger or inverter (or

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other large load) should be of equal length and wire size so the batteries will charge or discharge evenly. What is important is that the battery manufacturer's recommended charging voltages are being applied directly across the battery's terminals from the charging source. Using an adjustable Low Voltage Disconnect set to a minimum of 10.5 VDC (12.0 VDC is better) will insure a lower average Depth-of-Discharge and will protect electrical and electronic appliances and the batteries from damage from a real deep discharge and cell reversals.

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7.3.3. Which is Better, Two 6-volt Batteries in Series or Two 12-volt Batteries in Parallel?

Some battery experts believe that batteries in series are easier to discharge or charge because the same amount of current is applied to each cell and, with fewer cells, are a little more reliable. Batteries connected in series are also safer because if a cell shorts, the voltage will just be deceased. Other battery experts believe that batteries in parallel are better because they require less space, will have more capacity due to the Peukert Effect and if a cell should fail open, the bad battery can be disconnected and the other one can continue to be used. For safety, a DC fuse in series with each parallel battery is highly recommended. For additional information on this discussion, please read Collyn River's excellent article on Interconnecting Batteries, Ample Power's Parallel Batteries?, and Battery Configuration: Parallel or Series? published by Sierra Nevada Airstreams.

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7.3.4. How Do I Increase the Voltage?

If more voltage is need, connect identical batteries in series in the following manner:

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Batteries In Series

Two identical 6-volt batteries can be connected in series to produce 12-volts. Two identical 12-volt batteries or three identical 8-volt batteries can be connected in series to produce 24-volts. Three identical 12-volt batteries connected in series or six identical six-volt batteries will produce 36-volts and so on. Please note that the total amp hour capacity remains the same. Other voltage combinations are possible, but the battery type and amp hour capacity of each of the batteries in series should be the same because uneven discharging will cause charging problems.

You could also use a DC-to-DC Converter to produce different or constant DC voltage. A common problem is powering a laptop computer or other appliance requiring more than 14 VDC from a 12-volt battery or 12-volt appliances from 24, 36 or 48-volt battery banks. Using an efficient DC-to-DC Converter is highly recommended, automatic and eliminates the problems associated with wide voltage variances from uneven multi-battery discharges and recharges.

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7.3.5. How Can I Reduce the Voltage?

"Half-tapping" two batteries in series can be used to produce a source with half of the voltage, three batteries for one third and two thirds the voltage, and so on. For example and using the diagram below, let's assume that two identical 12-volt batteries are used in series to power a 24-volt trolling motor and there is a requirement to power 12-volt lights or electronic equipment. The 12-volt electrical appliances can be connected to the 12-volt batteries as long the 12-volt electrical loads are equally divided between the two 12-volt batteries, so the loads are balanced and fused. (In the diagrams below, the negative connection for Load 1 must be isolated from "ground" because it will place a dead short on the Battery for Load 2.) If batteries connected in series are discharged unequally, recharging the batteries with a single bank charger (a 24-volt charger in this example), will cause

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the battery (or cell) with the lowest capacity will overcharge or over discharge. Over time, this will significantly reduce the battery's service life. Collyn Rivers' article 12 volt Systems From 24 Volt Supplies has more options.

A better solution is to use a 24-volt to 12-volt DC-to-DC Converter or a separate 12-volt charging system and battery to produce 12-volts because an unbalanced load will not occur on the batteries and voltage variances. With batteries in series, if discharging unevenly or use of non-identical batteries can not be avoided, then use an isolated multi-bank charger, single bank charge with an external diode isolator (adjusted for the voltage loss), or combiner to recharge all of the batteries at the same time.

Below are examples of wiring diagrams of "half tapped" 12-volt, 24-volt, and 36-volt battery banks.

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7.3.6. Which Weighs More--One 12-volt or Two 6-volt Batteries?

With equal amp hour capacities, a single 12-volt battery will weigh approximately 10% less than two six-volt batteries connected in series due to the additional case material and the battery connecting cable. But, the two six-volt batteries can be split apart and each battery weighs approximately half of the weight of the 12-volt battery and is easier to transport.

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7.3.7. Can I Mix Old and New or Non-Identical Batteries?

To prevent charging problems when connecting batteries in series or series-parallel, do not mix old and new batteries, ones of different capacities or types. Mixing old batteries with new batteries is like mixing old milk with new milk--soon you have nothing but old milk. The weakest or smallest capacity battery (or cell) connected in series or series-parallel will over discharge and overcharge, which will eventually cause a premature failure. If replacing the weakest batteries occurs, "preconditioning" the new batteries is recommended by charging and discharging several cycles. If discharging the batteries unevenly or use of non-identical batteries has to occur, then use an isolated multi-bank charger, single bank charger with an external diode isolator (adjusted for the voltage loss), multiple chargers, or combiner to recharge the batteries all at the same time or recharge each battery separately. Batteries that will not produce at least 80% of their rated amp hour capacity are considered to be bad and should be replaced. Historically once a battery will not produce 80% of it's rated capacity, the failure rate goes up exponentially.

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7.4. Size

In North America, manufacturers build their batteries to an adopted Battery Council International (BCI) Group Size Number (U1, 24, 27, 31, 34, 35, 65, 75, 78, 8D, GC, L-16, etc.) standard. These specifications, which are based on the physical case size, terminal placement, type and polarity. In Europe, the European Committee for Standardization has adopted the ETN (European Type Numbering) standard to replace the older EN, IKC, Italian CEI, and German DIN standards. An ETN number (Battery Identification - BS EN 60095) is divided into three groups. The three digit first group is the voltage and amp hour capacity. For numbers below 500, the number is the amp hour capacity rating and a six-volt battery. For numbers above 500, subtract 500 from the number and that is the amp hour capacity for a 12-volt battery. The second three digit group indicates the battery's physical case size, case base hold down, type and layout of terminals (poles), and polarity. The third three digit group determines the EN cold cranking current in amps multiplied by 10. In Asia, the Japanese JIS standard is commonly used and in Russia GOST 959 is used.

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The OEM battery number is a good starting place to determine the replacement battery size. Within a size, the CCA and RC ratings, warranty and battery type will vary within models of the same brand or from brand to brand. Batteries are generally sold by model or series, so the size numbers will vary for the same price. For the same price, potentially a physically larger battery with more CCA or RC (or AH) can be purchased than the battery being replaced. For example, a 34/78 group might replace a smaller 26/70 group and give an additional 30 minutes of RC. If you buy a physically larger battery, be sure that the replacement battery will fit, the cables will connect to the correct terminals, and that the terminals will NOT touch metal surfaces such as the hood when it is closed.

The battery manufacturers publish application Selection Guides that contain OEM cold cranking amperage requirements and group number replacement recommendations by make, model and year of car, battery size, and CCA and RC (or Amp Hour) specifications. You can also find the BCI size information online at http://www.rtpnet.org/~teaa/bcigroup.html or in some of the Selection Guides in the Battery Manufacturers and Private Labels List found at http://www.batteryfaq.org. Manufacturers might not build or the store might not carry all the battery sizes. To reduce inventory costs, dual terminal "universal" batteries that will replace several group sizes are becoming more popular and fit 75% or more of cars on the road today.

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7.5. Terminals and Lugs

There are six types of common battery terminals: SAE Post, GM Side, "L", Stud, combination SAE and Stud, and combination SAE Post and GM Side. For automotive applications, the SAE Post is the most popular, followed by GM Side, then the combination "dual" SAE Post and GM Side. "L" terminal is used on some European cars, motorcycles, lawn and garden equipment, snowmobiles, and other light duty vehicles. Stud terminals are used on heavy duty and deep cycle batteries. The POSITIVE (+) SAE terminal post is slightly larger, 1/16 inch (1.6 mm), than the NEGATIVE (-) post. Terminal types, locations and polarity will vary. There are adapters available that will you allow to connect cables with "GM" style side terminals to batteries with top post terminals or visa versa. Additional terminals for deep cycle batteries can be found on http://www.usbattery.com/pages/usbterminals.htm. Lugs are the

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connectors on the ends of battery cables that connect to the terminals on the battery.

[Source: BCI]

Battery manufacturers or distributors will often "private label" their batteries for car manufacturers, large chain stores or export. An alphabetical list of most of the largest battery manufacturers/distributors, their Web addresses, telephone numbers and some of their brand names, trademarks and private labels can found in the Battery Manufacturers & Private Labels List on the http://www.batteryfaq.org/ Web site. Ownership, branding, Web addresses and telephone numbers will sometimes change.

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7.6. Freshness

Lead-acid batteries are perishable and sulfate in storage due to their natural self discharge, especially in temperatures above 80° F (26.7° C). Please see Section 16 for more information on sulfation.

Determining the "freshness" of a battery is sometimes difficult. Unless it has been periodically recharged or is "dry charged" (shipped without electrolyte), NEVER buy a wet Standard (Sb/Sb) or Low Maintenance (Sb/Ca) battery that is MORE than three months old or a wet "Maintenance Free" (Ca/Ca) battery that is MORE than six months old. Dry charged batteries are shipped without electrolyte, but usually have "sell by" dates of one to three years. Depending on the temperature, AGM (Ca/Ca) and Gel Cell (Ca/Ca) batteries that can be stored six to 18 months before the State-of-Charge drops below 80%. Please see Section   16. for more information on sulfation. Dealers will place their older batteries in storage racks so they will sell first and they do not have to maintain them. The fresher batteries can be found in the rear of the battery rack or in a storage room. For a wet battery, the date of formation is often stamped on the case or printed on a sticker. If at all possible, have a new battery tested, and recharged if necessary, before the battery leaves the store. This can save a lot of time and frustration if the new battery is sulfated or has a manufacturing defect.

Some of the manufacturer's formation date coding techniques are as follows:

7.6.1. Delphi (ACDelco) and some Sears DieHard

Dates are stamped on the cover near one post. The first number is the year. The second character is the month A-M, skipping I. The last two characters indicate geographic areas. For example, 0BN3=2000 February.

[Source: Interstate Batteries]

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7.6.2. Douglas

Douglas uses the letters of their name to indicate the year of manufacture and the digits 1-12 for the month, D=1994 O=1995 U=1996 G=1997 L=1998 A=1999 S=2000. For example, S02=2000 Feb.

7.6.3. East Penn, Exide (Champion), Johnson Controls Inc., Interstate, Chrysler (Mopar) and some Sears DieHard)

Usually on a sticker or hot-stamped on the side of the case. A=January, B=February, and the letter I is skipped. The number next to the letter is the year of shipment. For example, B0=Feb 2000.

        

[Source: Interstate Batteries]

7.6.4. Exide (some Sears non-Gold DieHards)

The fourth or fifth character is the month. The following numeric character is the year. A-M skipping I. For example, RO8B0B=February 2000.

[Source: Interstate Batteries]

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7.6.5. Optima

The first character is the year. The following three numeric characters are the days of the year. For example, 3123=3 May 2003.

7.6.6. Trojan

The date code on the negative post is stamped as the battery comes off of the finishing line, ready to ship out or go into stock. The code that is stamped is usually one month ahead. Therefore, a battery that comes out in March will carry an April date code. The code on the positive post is the manufacturing date that indicates when the battery was physically built but before the addition of any electrolyte. The letter is the month (A=Jan, B=Feb, C=March, etc.) and the number is the actual date. So "K26" means that the battery was ready for electrolyte filling and the first forming charge was on November 26th. Since the negative post shows A2 (January 2002), the manufacturing year has to be 2001.

7.6.7. Concorde

The activation date is found on an orange sticker on the shipping carton or email Concorde Customer Service with the serial number of the battery.

7.6.8. Rolls and Surrette

The four digit date code represents the day of the week (first digit), week of the year (middle two digits) and the year (last digit). For example, April 4, 2003 would have 4143 as a date code. The date code is stamped into the front edge of the cover of the battery.

7.6.9. U.S. Battery

The three digit date code represents the year (first digit), month (middle letter) and the plant code (last digit). For example, April, 2003 would have 3Dx as a date code. The date code is stamped into the positive terminal of the battery when it is formed. The characters burned into the case are the production run. For example A270N.

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7.6.10. Other Date Coding Methods

The four digit date code could represent the week of the year (first two digits) and the year (last two digits). For example, November 1, 2006 would have 4406 as a date code. The four digit date code could also represent the month of the year (first two digits) and the year (last two digits). For example, November 1, 2006 would have 1106 as a date code. The six digit date code could represent the month of the year (first two digits), day of the year (middle two digits), and the year (last two digits), or any other combination. For example, November 1, 2006 would have 110106 or 011106 as a date code. The date code is usually stamped into battery or printed on a sticker attached to the battery.

If you cannot determine the date code, ask the dealer or contact the distributor or manufacturer. Because of permanent sulfation due to self-discharge, a fresher battery is definitely better and does matter.

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7.7. Warranty

Battery warranties are not necessarily indicative of the quality or service life. Some dealers will prorate warranties based on the list price of the bad battery, so if a battery failed half way or more through its warranty period, buying a new battery outright might cost you less than paying the difference under a pro rated warranty. The exception to this are the free replacement warranties. They represent the risk that the manufacturer is willing to assume. A longer free replacement warranty period is generally better depending on the cost of the battery.

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7.8. Buying Tips

The following are some tips for consumers for buying car, motorcycle, truck, marine and recreational vehicle starting and deep cycle batteries. Before you buy a replacement battery, you should fully charge your old battery, remove the surface charge and test it. You could have a faulty charging system, loose alternator belt or corroded terminals and the old battery is good but was just discharged.

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7.8.1. Physical size matters!

Purchasing a battery has become much easier because most of the battery and vehicle manufacturers have adopted the BCI Group Number, European Type Number (ETN) which replaces DIN or JIS as a standard for the battery's voltage, physical size, and terminal type and location. Web based Battery Replacement Selectors or Fitment Guides published by battery manufacturers or distributors can make the task even easier. They contain the vehicle's minimum cold cranking amps (CCA) requirement and battery size replacement recommendations by make, model and year of manufacturer.

7.8.2. Pick the battery type that matches your charging system.

For starting an engine, using a car or starting battery is normally a better choice than a deep cycle battery because it is specifically designed for shallow (1%-3%) discharges. The battery type MUST match the vehicle's charging system or the new battery or charging system could be damaged. The easiest way to accomplish this is to replace your battery with the same or compatible type of battery that was originally installed by the vehicle's manufacturer. The exception to this is in hot climates, using a non-sealed wet car battery (with filler caps) is highly encouraged because lost water can be easily replaced. For batteries with side terminals commonly found in General Motors vehicles, check the terminal bolt length and do not over-tighten because you might crack the battery case and cause a leak.

For a deep cycle application, using a deep cycle battery is much better alternative than using a starting battery because the deep cycle battery will have a much longer service life when deeply discharged because the plates are thicker.

7.8.3. For car batteries, select the battery with CCA (Cold Cranking Amps) that will meet (or just exceed the vehicle manufacturer's recommendation), or is best suited for the coldest temperatures encountered in your climate. This is because more CCA requires greater plate surface area and in order to fit more surface area in the same space, this means thinner plates. Thinner plates will normally cause shorter overall service life. Do not substitute CA (Cranking Performance Amps), MCA (Marine Cranking Amps), or HCA (Hot Cranking Amps) for CCA. In hot climates, buying batteries with double

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or triple your vehicle's cranking amp requirements is a waste of money. Unless starting batteries are used in extremely cold climates, increased CCA is required to crank a sluggish engine and the over come the inefficiency of a cold battery. James W. Douglas' recommendation in his February 2000 article, Battery Selection--A Consumers Guide, in The Battery Man magazine, is:

"The sleek, aerodynamic designs have low cooling airflow through the engine compartment and that small in stature battery with high cold crank [amps] will have many very thin lead plates just to get the necessary surface area to make that big cold crank number. It will have the lower volume of electrolyte to provide the cooling necessary for long life and the greater capacity to run the [electrical] systems on the car. All of those thin plates will corrode away and fail long before expected putting the high performance battery's life below that of the lower CCA rated battery with the lower cost. Your best rule-of-thumb is, if it meets the OEM (Original Equipment Manufacturers) recommendation, buy it. Look for the highest reserve capacity [RC] battery at the correct CCA (Cold Cranking Amps)."

7.8.4. More Reserve Capacity (RC) or Amp Hours (AH) is a good thing.

Greater RC or AH is better because of the effects of increased parasitic (ignition key off) loads, normal battery self discharge while the vehicle is not being used, and the demands of stop-and-go city driving. Amp Hour (AH) ratings are normally used to describe the capacity of deep cycle and European car (starting) batteries. When comparing AH specifications, use the same discharge rates, expressed in hours. The most common is the 20 hour rate which is expressed as "C/20". It is the rate of discharge so a fully charged battery is discharged over a 20 hour period. For example, a 100 AH battery discharged at 5 amps per hour will take 20 hours to become discharged. If two batteries have the same capacity, the heavier battery has more lead and is normally better choice.

Batteries are generally sold by model or series, so the battery sizes can vary for the same price. This means that for the same price, potentially a larger battery with more RC (or Amp Hours) than be purchased than the battery being replaced. If a physically larger battery is bought, be sure that

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the replacement battery will fit, the cables will connect to the correct terminals, and that the terminals will NOT touch metal surfaces such as a closed hood (or bonnet).

7.8.5. Batteries are perishable, so buy the FRESHEST available.

Unless a battery has been periodically recharged, never buy a non-sealed wet Standard (Sb/Sb) or Low Maintenance (Sb/Ca) battery that is more than three months old, a sealed wet "Maintenance Free" (Ca/Ca) battery that is more than six months old, or sealed AGM (Ca/Ca) or Gel Cell (Ca/Ca) VRLA battery that is over 12 months old, because it may have some permanent sulfation and lost some capacity. "Dry charged" batteries are shipped and stored without electrolyte. The electrolyte is added and initially charged by the dealer or the buyer. They usually have "sell by" dates of one to three years. Battery dealers will often place their fresher batteries in the rear of the battery rack or in a storage room. The date of manufacture is often stamped on the case or printed on a sticker. If possible, have a new battery tested to insure it meets or exceeds it's advertised specifications, and recharged if necessary, before it leaves the store.

7.8.6. Look for longer free replacement warranties.

Pro rated battery replacement warranties or cost are not necessarily indicative of the quality over the life of the battery. The exception is the free replacement warranty, which represents the risk that the dealer, distributor, or manufacturer is willing to assume.

[back to Index]

7.9. How Do I Size The Components For Backup AC Power?

For AC backup power, here are the basic steps for sizing the deep cycle battery bank, inverter, AC battery bank charger and generator based on your AC power requirements. Deep Cycle battery bank capacity sizing is based on power requirements, inverter efficiency, wiring power loss, discharge rate (or Peukert Effect), electrolyte temperature, and desired average Depth-of-Discharge. DC to AC Power Inverters has a simple and easy to use battery capacity calculator at http://www.dcacpowerinverters.com/faq.htm#22. Please note that microwave ovens can have very large loads and might not be suitable for inverter or battery operation.

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7.9.1. Calculate the cumulative daily AC load in amps hours (AH) at 120 VAC. This will require determining how much current an appliance uses and for how long times the "duty cycle" (the amount of time the appliance is on during that time period). The label of the electrical appliance will have the amount of power and the voltage that the appliance uses. Power is expressed either in watts or in amps. If wattage is given, divide it by the voltage to convert to the number of amps.

For example:

a. Two 60 watt lights that you use continuously for four hours, the calculation would be 60 watts/120 volts = .5 amps and .5 amps x 4 hours x 2 lights = 4 Amp Hours @ 120 VAC.

b. A 200 watt refrigerator that is on for 24 hours with a 25% duty cycle, the calculation would be 200 watts / 120 volts = 1.67 amps and 1.67 amps x 24 hours x 25% duty cycle = 10 Amp Hours @ 120 VAC.

c. A five amp power drill that you use 15 seconds at a time for 25 times, the calculation would be 5 amps x 15 seconds/60 seconds/60 minutes x 25 times = .52 Amp Hours @ 120 VAC.

d. A 10 amp sump pump that is on 24 hours and has a 50% duty cycle, the calculation would be 10 amps x 24 hours x 50% duty cycle = 120 Amp Hours @ 120 VAC.

The total daily usage of these four appliances would be 4 AH + 10 AH + .5 AH + 120 AH = 134.5 Amp Hours @ 120 VAC per day.

7.9.2. Depending on the efficiency of the inverter and the power loss in the wiring, it takes between 12 and 14 amps of 12 VDC power to produce one amp of 120 VAC power or 24 to 28 amps to produce one amp of 240 VAC. Using the above example in the worst case, the usage would be 14 x 134.5 AH = 1883.3 Amp Hours per day @ 12 VDC.

7.9.3. Depending on the average load on the battery bank, the total daily usage may have to be adjusted due to the Peukert Effect. Deep cycle batteries are normally rated by the fully charged capacity divided by the number of hours of discharge it take to drop to 10.5 VDC. A very common rate is over a 20 hour period and is expressed as "C/20". In the example above, 1883.3 AH are being consumed in a 24 hour period which is a slightly lower rate than over a twenty hour period, so

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we could probably decrease the daily usage by 10% or 1883.3 AH x .9 = 1695 AH per day. If all of this power were consumed over six hour period, you would probably need to increase the daily usage by approximately 25%.

7.9.4. Depending on the temperature of the battery electrolyte, the usage might also have to adjusted. The example above assumes 80 degrees F. If your battery bank was operating at 60 degrees F then you would have to increase the usage by 10% and at 32 degrees F, by 20%. Let us assume the batteries are in a heated area at 70 degrees, so you would increase the daily usage by 5% or 1695 AH x 105% = 1780 AH per day.

7.9.5. Depending how many discharge/charge cycles you want your battery bank to last, you will need to increase the usage. Let's assume that you are fully recharging the battery bank daily and using "low end" inexpensive deep cycle batteries that when fully discharged (or 100% average Depth-of-Discharge) will last 50 cycles, at 80% average DoD (or 20% State-of-Charge) will last 200 cycles and at 50% average DoD will last 500 cycles. In this example, for 100% average DoD, you would require a battery bank with a capacity of 1780 AH to provide for 1780 AH of daily usage, at 80% DoD (1780 AH / 80% = 2225 AH), and at 50% DoD (1780 AH / 50% = 3560 AH). However, you would have to replace the smaller, less expensive battery bank every 50 cycles.

You can determine the optimum battery bank size by multiplying the number of cycles time the total amp hour capacity divided into the cost. For a simple example, let's assume that a 225 Amp Hour (C/20) 12-volt deep cycle battery costs $85. At 100% DoD, 1750 AH / 225 AH per battery = 8 batteries x $85 per battery = $680 total cost and 50 cycles x 1780 AH = 89,000 total AH. So $680 / 89,000 = .764 cents per amp hour. At 80% DoD, the calculation would be 2225 AH / 225 AH per battery = 10 batteries x $85 per battery = $850 total cost and 200 cycles x 2225 AH = 445,000 total AH. So $850 / 445,000 = .191 cents per amp hour. At 50% DoD, the computation would be 3560 AH / 225 AH per battery = 16 batteries and 16 batteries x $85 per battery = $1360 total cost and 500 cycles x 3560 AH = 1,780,000 total AH. So $1360 / 1,780,000 = .076 cents per amp hour. In this example, a larger, more expensive battery bank with a lower average 50% DoD will cost approximately one tenth the cost of fully discharging the battery bank (100% DoD) every cycle. This example does not take into consideration the additional maintenance, cabling cost, cost

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of money, etc. that would be used in a Total Cost of Ownership determination.

7.9.6. Once you have determined your daily capacity, then you need to determine how many hours or days you want to run using your battery bank before you recharge your batteries and decrease or increase the size of the battery bank accordingly. Please see Section   9 for more information on charging.

7.9.7. To size the inverter (or inverter portion of an inverter charger using the example above, calculate the worst case load (with all the appliance on at once) which is (60 watts x 2 lights) + 200 watts + (5 amps x 120 volts) + (10 amps x 120 volts) = 2120 watts @ 120 VAC. Be sure to consider the start surge power requirement of up to five time the run current with large inductive starting loads, such as microwave ovens, motors and transformers. Some "square wave" or "modified" sine wave inverters are not capable of providing the power to run some motors, compressors or other electronic or electrical appliances. In these cases, a "true" sine wave inverter must be used. For more information on power inverters, please see Don Rows' Frequently Asked Questions about Power Inverters.

7.9.8. To size the battery charger (or charger portion of an inverter charger), you will need the output to be at least 12% of the battery capacity used to fully recharge the batteries within 24 hours. Using the example above, you would need at least a 214 amp charger to replace 1780 AH in 24 hours.

7.9.9. To size an AC generator, using the example above without recharging the battery bank, the worst case load (with all the appliance on at the same time) is (60 watts x 2 lights) + 200 watts + (5 amps x 120 volts) + (10 amps x 120 volts) = 2120 watts @ 120 VAC. You would also need to consider the surge power requirement up to five times the run load. If you are using motors, take into consideration their peak starting current. If the batteries need to recharged the batteries in addition to using the appliances, add 214 amps/12 DC amps per AC amp = 17.8 amps @ 120 VAC and 17.8 amps x 120 volts = 2140 watts @ 120 VAC to power the battery charger. So, to power both the load and recharge the batteries, a generator with a capacity of 8000 to 12000 watts @ 120 VAC in required depending on the surge of the pump motor and battery charger.

As can be seen from this example, using just battery backup for one day for AC power with a heavy load can become very expensive, so that is why most "grid" or commercial AC power backup systems is an AC generator, combination of batteries and

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AC generator, or combination of battery and solar power with AC generator backup.

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7.10. How Do I Size Deep Cycle Batteries or Battery Banks?

As a general rule for longer service life, size deep cycle batteries or battery bank capacity so that the Depth-of-Discharge does not exceed 50%. For additional information on deep cycle battery bank sizing can be found, please see Glacier Bay Refrigeration's HOW TO SIZE AND USE YOUR BATTERY BANK, Constian von Wentzel's Sizing a Lead-Acid Battery Bank, or Optima's Marine [and RV] Calculation Information. To calculate the ampere draw for trolling motors based on the pound thrust of the motor, divide the pounds of thrust by the motor voltage and multiply by 12. For example, 40 pound thrust motor at 24-volts will draw approximately 20 amps. Information on splitting battery banks can be found in Chris Gibson's article on http://www.smartgauge.co.uk/splitting.ht

8. HOW DO I INSTALL NEW BATTERIES?

INDEX:

8.1. Installing Car and Marine Starting Batteries

8.2. Installing Deep Cycle Batteries

While working with car or deep cycle lead-acid batteries, please wear glasses to protect your eyes in the unlike event of an explosion. Do NOT install wet lead-acid batteries in confined area where there is ANY possibility that salt water can mix with the battery's electrolyte, like the bilge of a boat, because DEADLY chlorine gas is produced.

8.1. Installing Car and Marine Starting Batteries

In a 2003 marketing study in the U.S., consumers (or non-professional battery installers) installed almost 60% of the approximately 82 million replacement car batteries that were made in 1999. Car batteries were the fourth most popular item purchased among auto parts. The same study indicated that Wal-Mart (EverStart) has surpassed Sears (DieHard) as the number one car battery seller in the United States with Auto Zone (DuraLast) as the most popular of the U.S. auto parts stores for car batteries.

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Below are some questions you need to ask yourself because the installation of a replacement battery and disposal of the old one is usually included in the purchase price at some auto parts and battery stores:

How much money or time do I save if I install it myself?

Where is the battery located? Some car manufacturers locate the OEM (Original Equipment Manufacturer) battery under the rear seat, trunk or in the fender behind an access door in the wheel well.

A car battery weights between 30 and 60 pounds (13.6 and 27.3 Kg) and deep cycle battery can weigh several hundred pounds (or kilos), so am I physically capable of install it?

What do I do with the old battery if not exchanged for the new one? This is especially important if the batteries are not lead-acid, for example, Ni-Cad. The proper disposal of a non lead-acid battery could cost more that a new battery.

How do I save the radio station presets, emissions computer settings, or security codes before disconnecting the old starting battery?

Do I want to risk an injury or holes in my clothes?

If you decide to proceed, following is a list of easy steps to replace your battery and assumes that there the electrical and charging systems are in good condition:

8.1.1. In a well ventilated area, fully charge and test the new battery. Please see Section   9 for charging and Section   4 for testing the battery. If the battery is dry charged (shipped with out electrolyte), add the electrolyte but do not overfill, let stand for approximately one hour, and then slowly charge the battery at no more than 1% of the CCA or 10% of the amp hour capacity. Please see Exide's How To Charge a Dry Battery for additional information.

8.1.2. If a non-sealed wet battery, check the electrolyte levels after the battery has reached room temperature and "top off" to the proper level with distilled, deionized or demineralized water as required, but do not over fill. The plates need to be covered with electrolyte at all times to prevent an internal battery explosion or sulfation. (Please see Section   3.2 for electrolyte fill level information.)

8.1.3. Thoroughly wash and clean the old battery, battery cable lugs (connectors) and tray (case or box) with warm water to minimize problems

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from acid or corrosion. (Please see Section   3.3 for more information on corrosion.)

8.1.4. Mark all of the battery cable lugs or terminals so you will know how to reconnect to proper battery post and check the cables and cable lugs closely for damage. A loose terminal connection, corrosion, bad crimp (in especially a battery cable lug with multiple wires into it), or cut cable will cause high resistance and a large voltage drop when high current is running though it. If the cables are reversed, you can do extensive damage to your electrical system.

8.1.5. To prevent voltage spikes from damaging electronic equipment such as the emissions computer and to save the radio station presets, emissions computer and security code settings, temporarily connect a second 12-volt battery in parallel to the electrical system before disconnecting the first battery. If active when the key is off, a cigarette lighter plug can be used to easily connect a 12-volt parallel battery. Cigarette lighter adapters are available at electronics stores and "Computer Memory Saver" with a 9-volt battery are available at some auto parts stores, like JC Whitney for about $10.

8.1.6. Turn off the ignition switch, all electrical switches and breakers and electronic and electrical accessories and appliances. Do not use a hammer on the battery cable terminals or posts. Remove the grounded cable first because this will minimize the possibility of shorting the battery when you remove the other cables. The grounded cable is normally the NEGATIVE (-) cable, but it could be the positive cable in some older vehicles. Secure the grounded cable so that it cannot "spring" loose and make electrical contact. Next remove the remaining cable which is normally POSITIVE (+). Please remember that the battery terminal connector on the end of the POSITIVE (+) battery cable maybe "hot" (or have voltage on it from a parallel battery), so put it in a small plastic bag or cloth around it so that it will not touch the metal frame or engine components.

8.1.7. Carefully lift the old battery out and dispose of it by exchanging it when you buy your new replacement battery or by taking it to a recycling center. For additional information on recycling batteries, go to http://www.batterycouncil.org/recycling.html. Please remember that batteries contain large amounts of harmful lead, acid and other chemicals, so take great care with safety and please dispose of your old battery properly to protect our fragile environment.

8.1.8. After removing the old battery, insure that the battery tray or box and cable lugs are clean. Auto parts or battery stores sell an inexpensive brass wire brush that will clean the inside of post lug clamps and the post

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terminals. If the terminals, cables or hold-down brackets are corroded, replace them. A broken hold down bracket will cause excessive battery vibration and that will cause a premature battery failure. Replace any battery cables that are corroding, swelling or other damage with equal or larger diameter cable. Larger cable is better because there is less voltage drop. Please see Exide's Voltage Drop in Cables or Voltage Drop in Connections for additional information.

8.1.9. Check the positive and negative terminal markings on the replacement battery and position it so that the NEGATIVE (-) cable will connect to the NEGATIVE (-) terminal. Reversing the polarity of the electrical system can severely damage or DESTROY it. It can even cause the battery to explode.

8.1.10. After replacing and tightening the hold-down bracket, remove any plastic caps or covers on the terminals of the replacement battery, and reconnect the cables in reverse order, that is, attach the POSITIVE (+) cable first and the NEGATIVE (-) cable last. For General Motors-type side terminals, check the length of the bolt and do not tighten more than 4.2 to 5.8 foot pounds, or you could crack the battery case. For top terminals, do not tighten more than 5.8 foot pounds and 10 to 15 foot pounds for stud terminals. Connections need to be periodically checked for corrosion (or oxidation) and retightened, including the grounding cables between the vehicle's frame and engine block. If a parallel battery or "Computer Memory Saver" was used, disconnect it.

8.1.11. To prevent corrosion, coat the terminals and exposed metal parts with high temperature grease or silicone. Please see Section   3.3 for more information on corrosion.

8.1.12. Remove the parallel battery and reset all the switches and breakers, if required.

8.1.13. Test the new battery by starting your engine or with an electrical load.

Some vehicles have battery electrolyte level sensors. For Toyota and Nissan, use the sensor bypass information at http://www.exide.com/products/trans/na/battery_care/toyota_nissan.pdf and for Mazda use http://www.exide.com/products/trans/na/battery_care/mazda.pdf.

[back to Index]

8.2. Installing Deep Cycle Batteries

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Most of the steps above for installing car batteries apply to installing deep cycle batteries with these notable exceptions. Wire sizing and cable lengths are very important because wiring that is not large enough or different lengths will cause excessive voltage loss and undercharged batteries or, in some cases, a fire. Wiring size (and fusing) should be based on the maximum possible current carried through the wire. Good sources of information for surface vehicles (RV's, trucks, etc.) for measuring maximum cable and connector voltage drops can be found at Exide's Caring For Your Battery. Please note that SAE (Society of Automotive Engineering) wire is up to 12% smaller than AWG (American Wire Gauge) wire. To better balance the voltage with batteries in parallel, wire the connections from the POSITIVE (+) battery terminals to a single positive (+) distribution point and the connections from the NEGATIVE (-) battery terminals to a single NEGATIVE (-) distribution point. All of the interconnecting leads between the battery terminals and distribution points need to be exactly the same wire size and length so the voltage is the same. For parallel and series wiring diagrams, please see Section   7.3.2 . Use of bus bars is highly recommended for larger deep cycle battery bank installations.

Other good sources of information of wire sizing can be found in the Technical Information section at Ancor Products for boats and other marine applications, PowerStream or Solar Expert for solar applications. Using properly sized fuses or circuit breakers is also very important because they can provide protection for the wiring from over heating and for the electrical appliances. Good sources of basic information on connectors, fuses and wire can be found on how stuff works or Perry Babin's Basic Car Audio Electronics Web site at http://www.bcae1.com/fuses.htm and http://www.bcae1.com/wire.htm. Most rotary A/B battery selector switches are not recommended because the heavy inrush of current during the first few milliseconds that a switch is closed can burn the contacts or arc. Series, parallel, and series-parallel battery connection wiring diagrams can be found in Section   7.3.2. Connections will need to be periodically retightened. Another good source of information on measuring for maximum voltage drops can be found at Exide's Caring For Your Battery.

Insure there is adequate ventilation for the batteries so gases can dissipate while recharging and batteries can stay cooler. In other words, do NOT use sealed battery boxes, even with sealed Gel Cell (Ca/Ca) or AGM (Ca/Ca) VRLA batteries, because if there is shorted cell, a great deal of gassing could occur. Some batteries will require up to 50 "preconditioning" cycles before they will produce their rated capacity. This is because the acid needs to fully penetrate the pores of the newly formed plates. When mixing sulfuric acid and water to make electrolyte for dry charged batteries, always slowly add the acid to the water and NEVER add water to acid as it may boil violently and splatter.

9. HOW DO I CHARGE (OR EQUALIZE) MY BATTERY?

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INDEX:

9.1. What Are the Four Stages of Battery Charging?

Examples of Charging Algorithms

9.2. Additional Words of Caution

9.3. Battery Charger Types

9.3.1. Vehicle Charging System

9.3.2. Manual Constant Current Charger

Current Charging Table

9.3.3. Manual Constant Voltage Charging

Typical Battery Charging Voltages Table

Charging Voltage Temperature Compensation Table

9.3.4. Manual Taper Current Charger

9.3.5. Automatic Constant Voltage or Taper Charger

9.3.6. "Smart" Microprocessor-Controlled Charger

9.3.7. Float Charger and Battery Maintainer

9.3.8. Trickle Charger

9.3.9. High Rate Fast, Boost or Starting Assist Charger

9.3.10. DC Generators

9.3.11. Inverter/Charger

9.4. How Long Does It Take to Recharge a Good Battery?

9.5. How Do I Know When My Battery Is Fully Charged?

9.6. How Do I Know If My Battery Is Overcharged?

9.7. Battery Charger Buying Tips

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9.8. Is Opportunity Charging Worthwhile?

9.9. Is Gassing Good For a Wet Battery?

9.10. What is the Difference Between a Converter and a Charger?

9.11. What Are Charge Controllers or Voltage Regulators?

9.12. How Long Will a Deep Cycle Battery Last On a Single Charge?

9.13. How Can I Reduce Recharging Time?

9.14. How Can I Adjust the Specific Gravity?

9.15. How Do I Recharge Small SLA Batteries?

9.16. How Do I Recharge Unevenly Discharged or Non-Identical Batteries at the Same Time?

9.1. What Are the Four Stages of Battery Charging?

Three stages--bulk, absorption and float are normally used for wet car and motive deep cycle batteries with an optional equalizing stage. Three stages--bulk, absorption and float are normally used for AGM (Ca/Ca) and Gel Cell (Ca/Ca) VRLA car and motive deep cycle batteries. Three stages--bulk, float and equalization are normally used for wet stationary deep cycle batteries and two stages--bulk and float are normally used for VRLA stationary deep cycle batteries with an optional equalization stage is some cases.

9.1.1. The BULK stage is where the charger current is constant and the battery voltage increases, which is normally during the first 80% of the recharge. Give the battery whatever current it will accept as long as it does not exceed 25% of the 20 hour (expressed "C/20") ampere hour (AH) capacity rating, 10% of the Reserve Capacity (RC) rating, wet batteries do not exceed 125° F (51.5° C), and VRLA batteries do not exceed 100° F (37.8° C).

9.1.2. The ABSORPTION stage is where the charger voltage, depending on the battery type, is constant between 14.1 VDC and 14.8 VDC at 80° F (26.7° C) and the current decreases until the battery is fully charged, which is typically the last 20% of the recharge. For wet batteries, gassing (making a bubbling sound) usually starts at 80% to 90% of a full charge and is normal. A full charge typically occurs when the charging current drops off to 2% (C/50) or less of the AH capacity

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of the battery and each cell of a wet battery is moderately gassing equally. For example, end current for a 50 AH (C/20) battery is approximately 1.0 amp (1000 milliamps) or less. If the battery will not "hold" a charge, the current does not drop after the estimated recharge time, and a wet battery is hot (above 125° F (51.5° C)), then the battery may have some permanent sulfation. (Please refer to Section   16 for more information about sulfation and how to remove it.) Manual two-stage chargers that have a bulk and absorption stage must be turned off when the battery is fully charged to prevent overcharging.

9.1.3. The optional FLOAT stage is where the charge voltage, depending on the battery type, is reduced to between 13.0 VDC and 13.8 VDC at 80° F (26.7° C), held constant. It can be used indefinitely to maintain a fully charged battery to overcome the natural self-discharge of the battery. The current is reduced to approximately 1% (C/100) or less. Three-stage "smart" chargers usually have the bulk, absorption and float stages. (Please refer to Section   13 for more information about storing batteries and continuous float charging.)

9.1.4. The optional EQUALIZING stage is a controlled 5% to 10% absorption overcharge to equalize and balance the voltage and specific gravity in each cell. Equalizing reverses the build-up of the chemical effects like electrolyte stratification where acid concentration is greater at the bottom of the battery. It also helps remove sulfate crystals that might have built up on the surface or in the pores of the plates. The recommended frequency varies by motive deep cycle battery manufacturers from once a month to once a year. For stationary deep cycle batteries, some short daily (30 minutes or less) equalizations have proven to be beneficial and not require the longer equalization cycles. They are not as hard on a wet battery because they do not produce as much gas or heat the battery. You should equalize wet batteries when one or more of the following occur:

Where the temperature compensated Specific Gravity reading difference between cells is .030 (or 30 "points") or greater

Where the temperature compensated Specific Gravity reading difference of a cell is .010 (or 10 "points") or more below the reading for a fully charged cell when the battery is fully charged

When one cell requires more water than all the other cells

When one cell does not require as much water as all of the other cells

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When the SoC measured by a hydrometer does not materially agree with the SoC measured by an accurate (.5% or better) digital voltmeter

Some AGM (Ca/Ca) VRLA batteries, like Concorde, can be equalized under certain conditions, but carefully follow the battery manufacturer's recommended procedures or you will damage the battery.

To equalize, check that the electrolyte is covering the plates in each cell and fully recharge the battery. Then increase the charging voltage to the battery manufacturer's recommendation, or if not available, add 5% to 10% to the absorption charging voltage. Heavy gassing should start occurring in each cell. Do not allow the wet battery to get above 125° F (51.5° C) or a VRLA battery above 100° F (37.8° C). Take Specific Gravity readings in each cell once per hour. Stop equalizing when the Specific Gravity values no longer rise during the gassing phase and when every cell is gassing evenly. Insure that the plates are covered with electrolyte at all times, and add distilled, deionized or demineralized water if required, but do not overfill. Only equalize if the battery manufacturer recommends it. Four-stage "smart" chargers typically have the bulk, absorption, float and equalization stages.

An excellent and easy to understand tutorial on battery charging basics can be found at http://batterytender.com/battery_basics.php. The following graphs are examples of charging algorithms used by Deltran [Battery Tender] for power sport, car and deep cycle batteries:

Wet Standard (Sb/Sb)

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Wet Low Maintenance (Sb/Ca)

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Wet "Maintenance Free" (Ca/Ca)

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Absorbed Glass Mat [AGM] (Ca/Ca) VRLA

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Gel Cell (Ca/Ca) VRLA

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[Source: Deltran]

It is extremely important to use the battery manufacturer's recommended temperature compensated charging voltages and procedures whenever possible for optimum battery capacity, maintenance and service life. A good rule is not to use a charger (or charging setting) for batteries that is greater than 25% of the AH (C/20) capacity or 10% of the RC rating of the battery or battery bank being charged. For example, if the battery has RC of 100 minutes, do not use charger that will exceed 10 amps. The exception is when you are charging a large AGM (Ca/Ca) deep cycle battery bank. Due of the higher acceptance rate of the AGM (Ca/Ca) batteries a larger alternator to 33% of the capacity of the battery bank being charged can be used. Using a smaller alternator, unless temperature protected, can be damaged. The exception is not to use a charger (or charging setting) for SLA batteries that is greater than 10% of the AH (C/20) capacity.

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9.2. Additional Words of Caution and Charging Tips:

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9.2.1. Help prevent blindness and always wear glasses when working around a car or deep cycle battery in the unlikely event that it might explode.

9.2.2. Use the battery manufacturer's charging recommendations and temperature compensated voltages whenever possible for optimum capacity, maintenance and service life. MATCH the charger (or charger's setting) for the battery type you are recharging (or maintaining) and insure the charging voltages are compatible. Except for Gel Cell (Ca/Ca) VRLA batteries, a small overcharge is slightly better than an undercharge. Overcharging Gel Cell (Ca/Ca) VRLA batteries can cause voids between the plates and loss of capacity can result.

9.2.3. Lead-acid batteries should always be recharged within 24 hours after they have been used and the sooner the better. Before recharging, check the electrolyte and insure that it is not frozen and that it covers the plates at all times to prevent sulfation and to reduce the possibility of an internal explosion. Do not recharge frozen batteries because you will damage them. Allow them to thaw out first.

9.2.4. After recharging, recheck the electrolyte levels after the battery has cooled, top off with distilled, deionized or demineralized water as required, but do not overfill. (Please refer to Section   3.1. for more information about filling batteries.)

9.2.5. Reinstall the vent caps on wet (flooded) batteries before recharging and recharge ONLY in well-ventilated areas because explosive and toxic stibine or arsine gasses can be produced during the absorption stage. Insure the vent caps are not clogged. Do NOT expose lead-acid batteries to a lit cigarette, sparks or flames because they produce flammable gasses and could explode.

9.2.6. Follow the charger manufacturers' procedures for connecting and disconnecting cables. Connect the positive (+) lead of the charger to the positive (+) terminal post of the battery to be charged and the negative (-) lead of the charger to the negative (-) terminal post. Operate in a manner to minimize the possibility of an explosion or incorrectly charging the battery. You should always turn the charger OFF or unplug it before connecting or disconnecting cables to a battery. Do not wiggle the cable clamps while the battery is recharging, because a spark might cause an explosion. Good ventilation or a fan is recommended to disperse the gas created by the recharging process for wet batteries. As a safety feature, some chargers are designed not operate unless the battery has a partial charge or if the leads are reversed.

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9.2.7. If a wet battery becomes hot, over 125° F (51.5° C), or if it violently gasses or spews electrolyte, turn the charger off temporarily or reduce the charging rate. This will also prevent "thermal runaway" that can occur with AGM (Ca/Ca) and Gel Cell (Ca/Ca) VRLA batteries if the battery temperature is over 100°F (37.8° C). If an air cooled alternator becomes too hot during the bulk charging phase, stop and let it cool down or use an alternator temperature sensing voltage regulator, like a Balmar, or a water cooled alternator, Bosch for example.

9.2.8. Insure that charging the battery with an external charger will not damage the electrical system or appliances with high voltages. If this is even a remote possibility, then disconnect the grounded battery cable from the battery before connecting the charger to the battery.

9.2.9. If you are recharging Gel Cell (Ca/Ca) VRLA batteries, the battery manufacturer's charging voltages are very critical. You might need special charging equipment. In most cases, standard deep cycle chargers used to recharge wet batteries cannot be used to properly recharge Gel Cell (Ca/Ca) or AGM (Ca/Ca) VRLA batteries because of their higher voltages or charging profiles. Overcharging Gel Cell (Ca/Ca) and AGM (Ca/Ca) batteries will significantly shorten battery service life or cause "thermal runaway" if the battery temperature is over 100°F (37.8° C).

9.2.10. If a battery is charged with a manual or defective charger and all the electrolyte is "boiled" out, some batteries can cause a FIRE or produce DEADLY CO (Carbon Monoxide) or other gasses.

9.2.11. Routinely tighten cables connections.

9.2.12. Never disconnect a car battery cable from a vehicle with the engine running, because the battery acts like a filter for the electrical system. Unfiltered (pulsating DC) electricity sometimes exceeding 40 volts is produced by the alternator and can damage expensive electronic and electrical components such as emissions computer, audio system, charging system, alarm system, etc.

9.2.13. Alternators are not designed to recharge dead (or flat) batteries and the stator can be burned or diodes go bad.

9.2.14. Wet battery gassing usually starts at 80% of a full charge during the absorption stage. A full charge normally occurs when the charging current drops off below 2% (C/50) of the AH capacity and the battery is moderately gassing (bubbling). For example, the end current for a good 50 AH (C/20) battery is approximately 1.0 amp (1000 milliamps) or less depending on the battery type.

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9.2.15. Do not recharge batteries with cracked or leaking battery cases.

9.2.16. Recharge battery banks the same way you discharged them. For example, if you discharged two or more fully charged and identical batteries connected together such that all the batteries discharged the same, i.e., the same State-of-Charge (SoC) readings on all of the batteries, you should recharge them connected the same. If you discharged two or more fully charged and identical batteries not connected together such that the batteries discharged differently, i.e., different State-of-Charge readings on each of the batteries or banks, you should recharge them separately. When the batteries are connected together in a bank(s), it is a question for keeping the discharges and charges balanced; otherwise, you will undercharge or overcharge one or more of the batteries or banks. Over time, undercharging will reduce capacity due to the accumulation of sulfation. The total time to recharge the batteries or banks together or individually is about the same because you have to replace the amp hours consumed.

9.2.17. Do not recharge batteries directly from a gas or diesel powered generator that does not have regulated DC voltage and most do not. A better approach to recharging batteries is to power a "smart" battery charger with the generator so the batteries are not overcharged or undercharged.

9.2.18. Continuous float charging or periodic recharging will prevent batteries from freezing. An Electrolyte Freeze Points at Various States-of-Charge for a Wet Lead-Acid Battery table indicates the temperature when the electrolyte will freeze.

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9.3. Battery Charger Types

Basically, there are three battery charger configurations--single bank, multi-bank and multi-station. A single bank charger is one that is designed to provide a single voltage to recharge a single battery or bank of batteries. It is by far the most widely used configuration. A multi-bank charger provides single voltages to multiple banks of batteries by using an internal isolator. This type of charge can also act as a single bank charger and commonly used to recharge unbalanced two, three or four 12-volt batteries in series to power a motor. A multi-station charger is a used to recharge more than one battery at the same time. It is functionally two or more single bank chargers in the same case.

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Unless the charging system or charger has adjustable voltage settings, there is no one system that can recharge all battery types. For example, if the absorption charge voltage is set for a Low Maintenance (Sb/Ca) or AGM (Ca/Ca) VRLA battery at 14.4 VDC, the system would undercharge most wet Standard (Sb/Sb) or wet "Maintenance Free" (Ca/Ca) and overcharge some Gel Cell (Ca/Ca) VRLA starting batteries. This would reduce the battery's service life. Unless a charger is temperature compensating, it is assumed by the manufacturer to operate at 77° F (25° C). Some chargers are equipped with an electronic switch that senses battery voltage at some predetermined level before the charger will operate. For deeply discharged batteries, this gives the appearance that they can not be recharged. Please see the charger manufacturer's operator manual for instructions on how to override this "soft start" feature. A good quality charger used on a cheap battery is better than a bad quality charger used on a good battery.

9.3.1. Vehicle Charging System

A vehicle charging system is made up of three components, an alternator (or DC generator), voltage regulator and a battery. Usually when a vehicle is jump started, it is NOT driven long enough to fully recharge the battery. The length of time to fully recharge the battery depends on the amount of discharge, the amount of surplus current that is diverted to the battery, how long the engine is run, engine speed, and ambient temperature. An alternator is sized by the vehicle manufacturer to carry the maximum accessory load and to maintain a battery and NOT to recharge a dead battery. For example, if 300 amps were consumed for two seconds to start a car from a fully charged battery, it will take an 80 amp charging system approximately 7.5 seconds to replace the .167 amp hours of power used. If 25 amps are available to recharge the battery, it will take 24 seconds and 10 minutes at one amp. With a dead 120 minute RC (60 amp hour) battery, it would take approximately 90 minutes at 80 amps, 4.8 hours at 25 amps, or 120 hours at one amp to fully charge (100% State-of-Charge) it.

More information can be found in Section   5 or Dan Landiss' Car Batteries Are Not 12 Volts on http://www.landiss.com/battery.htm about vehicle charging systems. Some battery experts believe that some vehicle charging systems undercharge starting batteries and that the batteries should be periodically recharged with an AC "shore" powered battery charger to optimize their service life

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by removing accumulated lead-sulfate or electrolyte stratification.

If you have added after-market lights, winches, audio amplifiers, two-way radios or other high powered accessories to your vehicle and engage in stop-and-go driving, the vehicle's charging system might not produce enough current or voltage to keep your battery fully charged. You might need to increase the capacity of the charging system. If you are also recharging deep cycle battery banks, please see the caution in Section 9.2.7. above. Ideally the combined load of all the accessories should be less than 75% of the charging system's maximum output, so that at least 25% is available to recharge the battery.

VEHICLE CHARGING VOLTAGE

[Source: Bosch]

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9.3.2. Manual Constant Current Charger

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A manual constant current charger chargers the battery at a constant current rate and the battery voltage will increase as the State-of-Charge rises. If you use an external constant current charger, set it to deliver NO more than the lesser of 1% of the CCA, 12% of the RC rating, or 25% of the C/20 rated AH Capacity of the wet battery and also carefully monitor the current flowing into the battery. C-rate is a measurement of the charge or discharge of battery over time. It is expressed as the Capacity of the battery divided by the number of hours to recharge or discharge the battery. For example, a 48 amp hour battery would have a charging or discharging rate of 4.8 amps for ten hours. With manual chargers, you need to determine how many amp hours have to be replaced and determine the amount of charging time based on the constant current output of your charger. Manual constant current chargers will overcharge a battery if not turned off when the battery is fully charged. Some constant current chargers have a timer that can turn off the charger and help prevent it from overcharging the battery. These types of chargers are not recommend to recharge a VRLA battery because the absorption voltages are critical, especially for Gel Cell (Ca/Ca) VRLA batteries.

For fully discharged wet batteries, the following table lists the recommended battery charging rates and times using a constant current charger:

CONSTANT CURRENT CHARGING

Reserve Capacity (RC) Rating

Slow Charge (RECOMMENDED)

Fast Charge

80 Minutes or less [32 ampere hours or less]

15 Hours @ 3 amps

5 Hours @ 10 amps

80 to 125 Minutes [32 to 50 ampere hours]

21 Hours @ 4 amps

7.5 Hours @ 10 amps

125 to 170 Minutes [50 to 68 ampere hours]

22 Hours @ 5 amps

10 Hours @ 10 amps

170 to 250 Minutes [68 to 100 ampere hours]

23 Hours @ 6 amps

7.5 Hours @ 20 amps

Above 250 Minutes [over 100 ampere

24 Hours @ 10 amps

6 Hours @ 40 amps

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hours]

[Source: BCI]

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9.3.3. Manual Constant Voltage Charger

A manual two-stage (bulk and absorption) constant voltage charger applies a regulated voltage to the battery at a constant level during the absorption stage. The current drops to below 2% (C/50) of the battery's capacity at the battery manufacturer's recommended absorption voltage when it approaches 100% State-of-Charge; then the charger needs to be manually turned off. The recommended charging method using a constant voltage charger is to slowly recharge the battery using a charger sized to recharge the battery over a ten-hour period (C/10). To prevent damage to a fully discharged battery, the current should be less than 1% of the CCA (Cold Cranking Amps) rating during the first 30 minutes of charge. The charger (or DC power supply) should be adjusted to the battery manufacturer's absorption voltage recommendations without the battery connected before charging. Typical battery charging voltages are in the table below with the electrolyte temperature at 80° F (26.7° C), but the battery manufacturer's temperature compensated charging voltages and procedures should always be used, if available. A manual constant voltage charger (or DC power supply) could overcharge and damage a battery if not turned off when the battery is fully charged.

TYPICAL BATTERY CHARGING VOLTAGESat 80 Degrees F (26.7 Degrees C)

Battery Type Ca=Calcium

Sb=Antimony

Absorption Charging Voltages

Float Charging Voltages

Equalizing Charging Voltages

Wet Standard 14.5 13.2 15.5

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(Sb/Sb) Deep CycleWet Low

Maintenance (Sb/Ca)

14.4 13.2 15.8

Wet "Maintenance Free" (Ca/Ca)

14.8 13.2 15.8

AGM (Flat Plate) VRLA

14.3 13.6 15.6*

AGM (Spiral Wound) VRLA

14.6 13.6 Not Applicable

Gel Cell (Ca/Ca) VRLA

14.1 or 14.4*

13.8 or 13.2*

Not Applicable

*  Verify with the battery manufacturer.

If the external or "shore powered" charger is NOT temperature compensating, you should adjust the charging voltage using the battery manufacturer's recommended temperature compensation voltages. If not available, then use the values from the table below to correct for the temperature of the electrolyte in the battery. If the electrolyte temperature can not be measured and the battery has not been recently moved from a warmer or colder location, charged or discharged, the ambient air temperature can be used. For example, if the electrolyte temperature is 20° F (-6.7° C), then increase the charging voltage to 15.408 volts for a wet Low Maintenance (Sb/Ca) battery if the normal absorption charging voltage is 14.4 at 80° F. If 100° F (43.3° C), then decrease the absorption charging voltage to 14.064 volts for the same battery.

CHARGING VOLTAGETEMPERATURE COMPENSATION

@ 2.8mv/degree F/cell

Electrolyte Temperature

Degrees F

Electrolyte Temperature

Degrees C

Add to Charger's Output Voltage

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160° 71.1° -1.344150° 65.6° -1.176140° 60.0° -1.008130° 54.4° -.840120° 48.9° -.672110° 43.3° -.504100° 37.8° -.33690° 32.2° -.16880° 26.7° 070° 21.1° +.16860° 15.6° +.33650° 10° +.50440° 4.4° +.67230° -1.1° +.84020° -6.7° +1.00810° -12.2° +1.1760° -17.8° +1.344

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9.3.4. Manual Taper Current Charger

The taper current chargers have no controlled current and voltage and are dependent upon the internal resistance of the battery. The current starts high and tapers off as the voltage increases when the battery approaches 100% State-of-Charge (SoC). With a taper charger, a high current (up to C/2), can be only applied to non-sealed wet batteries for 30 minutes maximum or until the battery heats up to 125° F (51.7° C). The current is then regulated downward by the battery until the charge state reaches 100% where it is at a minimum (2% or less) at the battery manufacturer's recommended absorption voltage level. A better approach to recharge the battery with a taper charger is to size the charger to recharge the battery over a minimum of a ten-hour period (C/10). This technique allows the acid more time to penetrate the plates and there is less mechanical stress on the plates. Manual taper current chargers will overcharge a battery if not turned off when the battery is

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fully charged and are not recommend to recharge VRLA batteries.

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9.3.5. Automatic Constant Voltage or Taper (Ferroresonant) Charger

The next step up is an "automatic" two-stage (bulk and absorption) charger that will stop charging when the battery has approached a full charge by turning off at some predetermined current, voltage cut-off point, time, or combination of current, voltage or time. If the battery manufacturer's recommended absorption voltage is used, there is less chance of under or overcharging a battery than with a manual charger. A four to 10-amp automatic starting battery charger will cost approximately $50 (US) and is suitable for most simple car battery charging applications with battery capacities up to 100 amp hours (C/20). Some automatic two-stage chargers, like the Dual Pro, Ctek XS 800, etc. will turn back on and recharge the battery when the voltage drops to a predetermined point (normally 90%-95% SoC). Some also have features like selection of battery type; temperature compensation, which is critical if recharging occurs in temperatures other than 80° F (26.7° C); do not produce sparks when the clamps are connected; will not turn on if the polarity is reversed; or will help prevent VRLA battery "thermal runaway".

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9.3.6. "Smart" Microprocessor-Controlled Charger

The best chargers for wet and some AGM (Ca/Ca) starting and motive deep cycle batteries are four-stage "smart" microprocessor-controlled temperature compensating chargers. They will automatically switch between bulk, absorption, float, and equalizing charging and some have adjustable voltage set points or selection for the different battery types, automatic temperature compensation, or features found in automatic two-stage chargers. The best chargers for Gel Cell (Ca/Ca) or AGM (Ca/Ca) VRLA batteries are the less expensive three-stage temperature compensating versions that have bulk, absorption and float charging capability (or settings) especially designed for

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VRLA batteries. They will also help prevent VRLA battery "thermal runaway". When continuously connected, the microprocessor based "smart" chargers can continuously charge a battery and keep it fully charged indefinitely. Some one-half to two-amp three-stage versions cost less than $50 (US), for example Battery Tender Plus, BatteryMINDer, etc., are ideal for for maintaining starting and deep cycle batteries (less than 100 AH) that are used less than once per week. Good application examples are for power sport vehicles (ATVs, Jet skis, motorcycles, snowmobiles, etc.), RVs, caravans, farm and lawn tractors, and antique vehicles and vehicles in storage.

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9.3.7. Float Charger and Battery Maintainer

There are basically two types of float chargers. The first type is used to float or maintain wet or VRLA car or motive deep cycle batteries that have been fully charged. The second type is used to float charge or maintain wet or VRLA stationary deep cycle batteries.

If you are using wet or VRLA batteries in starting or motive deep cycle applications and already have a two stage charger, then a voltage-regulated "float" charger, power supply or battery maintainer set at approximately 13.2 VDC can be continuously used after the battery has been fully charged. An example is a Vector VEC080, costing less than $30 (US). Float chargers will maintain batteries at a 100% State-of-Charge with a C/100 rate to offset the battery's internal self-discharge and prevent them from sulfating. Batteries that have the same plate chemistry (battery type) can be connected in parallel to a float charger after they have been fully charged and the charger's current output capacity is greater than 1% of total amp hour capacity of the batteries connected to it.

If you are using wet or VRLA deep cycle batteries in stationary applications, then use a float charger at approximately 13.8 VDC that is sized to carry the maximum load plus an extra 10% or more depending on how fast you want to recharge the batteries.

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9.3.8. Trickle Charger

A trickle charger is typically a cheap, unregulated voltage (C/100) charger used to maintain a battery after it has been fully charged typically costing less than $20 (US). Do NOT use these types of chargers because they can easily overcharge and destroy the wet battery by "boiling" the electrolyte out and dry out the battery or undercharge it. If you have to use a trickle charger, using it on a timer is highly recommended.

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9.3.9. High Rate Fast, Boost or Starting Assist Charger

High rate fast, boost or starting assist chargers (or settings) are high rate chargers that are designed to provide high current for up to 15 seconds to start your engine when the battery is discharged. These types of chargers (or boost settings) to recharge your battery are NOT RECOMMENDED because they can easily overcharge and destroy it with excessive current or voltage. If one is used, please do it with extreme caution in a well ventilated area and adhere to the charger manufacturer's recommended procedures.

9.3.10. DC Generators

Vehicle generators capable of producing Direct Current were used up until the 1950's to recharge car batteries. They were replaced by alternators because generators were not as reliable because of their mechanical voltage regulation, expense to manufacturer, and added weight. Most portable "generators" used today are alternators to produce AC voltage. Some have rectifying diodes to produce "DC" voltage to replace batteries for 12-volt loads. These portable DC generators can provide a bulk (up to 80% State-of-Charge) or equalizing charge to a battery that has been disconnected from the it's load. But check the output voltage across the battery terminals, recharge with care, and monitor the process because they typically do not have voltage regulation, can easily under or overcharge the battery and destroy it. You will require 14.1 to 14.8 VDC depending of

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the battery type to fully recharge your batteries at 80 degrees F. Generators without voltage regulators are NOT RECOMMENDED for absorption or float charging. A better approach would be to use a "smart" external "shore power" battery charger, like a Vector, plugged into the AC output of a portable generator to provide the voltage regulation to properly recharge the house batteries.

9.3.11. Inverter/Charger

Inverter/Charger is an AC to DC battery charger with a built-in DC to AC converter popularly known as an "inverter" that is battery powered when AC or "shore power" in not available. Some manufacturers of inverter/chargers are Mastervolt, Newmar, Parallax, Progressive Dynamics, TrippLite, Victron, Xantrex, and others. When selecting an inverter/charger be sure that the charger matches the battery type you are trying to charge and will produce the battery manufacturer's recommended temperature compensated charging voltages. Some inverter-charger combinations are float chargers for stationary batteries and will only produce a maximum of approximately 13.8 VDC, so your need to periodically give the batteries an absorption or equalizing charge to extend their overall service lives.

Hyperlinks to battery chargers, "smart" chargers, float chargers and battery maintainers can be found in the Battery References and Information Links List at http://www.batteryfaq.org. Please remember to match the charger to the battery manufacturer's recommended temperature compensated charging voltages for that type of battery or match the batteries to the charger capability. The better the match, the longer the service life and more capacity the battery will have.

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9.4. How Long Does It Take To Recharge a Good Battery?

When a battery is discharged, more power has to be replaced due to loss. However, some of the power is converted to heat and lost due to the resistance in the cables, connectors and elements within the battery. For most batteries that are discharged less than 20% of their full capacity, an estimate of time is the amp hours to be replaced divided by the current output of the charger. For example, a 40 amp hour battery with a 5% discharge would require

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approximately two amps hours to be replaced. Using a five-amp charger, it would take approximately 24 minutes (2 amp hours/5 amps x 60 minutes) to recharge the battery. A 10-amp charger would take approximately half the time or 12 minutes. For batteries that are discharged more than 20% of their full capacity, an estimate of time is twice the amp hours to be replaced divided by the current output of the charger. For example, a 40 amp hour battery with a 95% discharge would require approximately 38 amp hours to be replaced. Using five-amp charger, it would take approximately 15.2 hours recharge the battery. A 10-amp charger would take approximately half the time.

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9.5. How Do I Know When My Battery Is Fully Charged?

In descending order of accuracy and depending on the battery type, one or more of the following three methods is normally used to determine if a battery is fully charged:

According to IEEE   450-2002 Annex B Recommended Practice, "The pattern of charging current delivered by a conventional voltage-regulated charger after a discharge is the most accurate method for determining state of charge. As the cells approach full charge, the battery voltage rises to approach the charger output voltage, and the charging current decreases. When the charging current has stabilized at the charging voltage, the battery is charged, even though specific gravities have not stabilized." It should be less than two percent of the capacity (C/50) at the manufacturer's recommended temperature compensated absorption charging voltage level of the battery. For the average sized wet Low Maintenance (Sb/Ca) car battery (BCI Group 24) at 80° F (26.7° C), that would be less than two amps at 14.4 VDC with the cells gassing (bubbling) freely and evenly.

If not sealed, remove the surface charge by one of the methods in Section   4.3. , measure the cells with a hydrometer, and compare the average of the readings with the battery's manufacturer's temperature compensated Specific Gravity definition of a cell in a fully charged battery.

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If sealed, remove the surface charge, measure the Open Circuit Voltage (OCV) with an accurate (.5% or better) digital voltmeter across the terminals, and compare the reading with the battery's manufacturer's temperature compensated OCV definition of a fully charged battery.

After the battery has cooled to room temperature, recheck the electrolyte levels. The plates must be covered at all times to prevent an internal explosion or sulfation. If the battery will not "hold" a charge, the charging current does not drop below 2% (C/50), and is warm or hot, then it might have some permanent sulfation. Please refer to Section   16 for more information about sulfation and how to remove it.

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9.6. How Do I Know If My Battery Is Overcharged?

Normally, overcharging will consume more water from a wet battery than normal and the electrolyte levels will be low. Other signs of overcharging wet batteries are a "rotten egg" odor, violent gassing, spewing of electrolyte, black "tide-marks" on the inside walls of the cells, or black deposits on the bottoms of the filler caps. Other signs of overcharging are lumpy brown sediment or muddy red or brown electrolyte. Signs of overcharging a AGM (Ca/Ca) or Gel Cell (Ca/Ca) VRLA or SLA battery are a hissing sound, loss of capacity or overheating. If overcharging occurs, test the charging voltages.

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9.7. Battery Charger Buying Tips

The following are some tips for consumers on buying battery chargers for car and deep cycle lead-acid batteries. Please see Section 7.1 for definitions of the battery types. An excellent and easy to understand tutorial on Battery Charging Basics can be found at http://www.batterytender.com/.

9.7.1. Always wear glasses when working around a battery in the unlikely event that it might explode.

9.7.2. MATCH the charger's output voltages to the battery type and manufacturer's recommended absorption, float and equalization (if

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required) charging voltage requirements. A mismatch can easily overcharge or undercharge the battery. Some charger manufacturers state that their chargers are able to recharge all or most battery types. There are differences in the charging voltages and profiles (algorithms) for each battery type, so one charger setting can NOT possibly fit all types of batteries because of the differences in plate chemistries and alloys used. If the documentation that came with the battery or charger or the manufacturer's Web site does not state voltages, contact one of their Customer Service representatives and ask. If you do not charge your batteries at 80° F (26.7° C), temperature compensation needs to occur on the charging voltages to properly recharge the battery. A recent study has shown that cell equalization will significantly increase the life of wet (or flooded) Standard (Sb/Sb), Low Maintenance (Sb/Ca), "Maintenance Free" (Ca/Ca) batteries. Equalization is NOT recommended for Gel Cell (Ca/Ca) and most AGM (Ca/Ca) VRLA batteries.

9.7.3. Size the charger based on the discharge amount and how fast you need to use the batteries again. Slow recharging is recommended, so chargers that are sized 10% of the capacity of wet, AGM (Ca/Ca) or Gel Cell (Ca/Ca) VRLA batteries should be used. Fast or "boost" charging batteries can kill batteries because they can warp the battery's plates. Do not exceed the battery manufacturer's charging current or voltage limitations. For most car batteries, a charger output of four to 10 amps should be sufficient and for motorcycle and power sports batteries, one to two amps. For more information on charger sizing, please see Chris Gibson's article on http://www.smartgauge.co.uk/chargesize.html.

9.7.4. Determine special features you want, for example, "smart" microprocessor controlled, "automatic shut off" (two stage), automatic temperature compensation, "soft start" (no sparking when leads are connected), portability, waterproofing, indicators, ammeter, lead polarity reversal protection, short circuit protection, high temperature protection, etc.

9.7.5. Determine the total cost of ownership. Shop online on the Internet by using search engines, like http://www.google.com or http://www.yahoo.com to find the best prices. A charger is a long term investment and a good charger used on a cheap battery is much better choice than a bad charger used on a good battery.

9.7.6. If you have a two-stage charger, use a float charger (or battery maintainer). After the battery has been fully charged with a two stage charger or the vehicle's charging system, you can continuously maintain the full charge with a voltage regulated, one-half to two-amp

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float charger matched to your battery type while the battery is not being used. This will prevent sulfation from occurring while the battery is not being used. Cheap, unregulated "trickle" chargers can overcharge and destroy your battery.

9.7.7. If you use a one-half to two-amp "smart" charger, like a Battery Tender Plus, to recharge a larger battery, you might have to periodically "reset" the charger every six hours, by unplugging it and plugging it back in. Some small output "smart" chargers have fixed timers that will switch the absorption mode to float mode, thus not allowing sufficient time for a large capacity battery to be completely recharged. This fixed timer is used to keep a sulfated battery from boiling dry.

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9.8. Is Opportunity Charging Worthwhile?

Opportunity charging is recharging in between the normal daily charging cycle. An example is a electric fork lift truck battery being recharged when not in use during the workday and during meal breaks. Some experts will argue that a deep cycle battery should be sized so that the average Depth-of-Discharge (DoD) should not fall below 50% (or 80% depending of the plate chemistry). And the battery should be charged only once per day because each charge cycle removes a microscopic layer from the entire grid and eventually the upper portion of the grid can not carry the current. That is one of the main reasons that grid design and composition is extremely important in lead-acid batteries for a long service life. Other experts will argue that opportunity charging significants lowers the average DoD and causes multiple, shallower cycles per day, which is better than a higher average DoD and a single deep cycle per day with a lower average DoD. The answer to this question probably lies somewhere in the middle. You will need to compare the effects of lower average DoD and multiple cycles vs. greater DoD and one cycle by using the battery manufacturer's data to determine the break even point. Generally, opportunity charging is good, especially when the average DoD is between 20% and 50% and you can fully recharge battery at least once during a 24 hour period when being used and once per week while it is not in use to prevent sulfation.

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9.9. Is Gassing Good For a Wet Battery?

When a wet (flooded) Low Maintenance (Sb/Ca) battery reaches the absorption stage which is approximately 14.4 VDC at 80° F (26.7° C) or 80% State-of-Charge during a charge, it will start to gas (bubble) and is a normal part of the charging process. Gassing is the electrolysis of water into two parts Hydrogen gas and one part Oxygen gas and can be explosive. The gas bubbles given off by the plates will help to mix the electrolyte as they rise to the surface. This will help to prevent electrolyte stratification. Electrolyte stratification is acid concentration that is greater at the bottom of a battery than at the top, especially within batteries with more than 100 amp hours capacity. Normal charging should produce moderate amount of even gassing of all cells, which is good. Overcharging a battery or rapidly charging with high voltage will produce heavy gassing, heat, consume excessive quantities of water, accelerate positive grid corrosion, warp the plates, and is NOT recommended. Ventilation is required for all lead-acid batteries and good ventilation is mandatory for wet batteries to dissipate the explosive and toxic gasses produced during charging.

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9.10. What is the Difference Between a Converter and a Charger?

An AC-DC Converter (or AC-DC Power Supply) is used to convert 120 or 240 VAC power to filtered 12 to 13.8 volt DC power to run DC appliances while connected to "shore power" instead of running on "house" battery power. Converters are normally voltage regulated to provide a constant supply of DC power and if the voltage is high enough, partially recharge a battery. To fully recharge a battery, you will need 14.1 to 14.8 volts at 80 degrees F, depending on the battery type. If you use a converter or converter/inverter, then you should fully charge your batteries at least once per week. While connected to shore power, a better solution is to temporarily separate the house load from the house batteries, use the converter to run your house load, and use a "smart" charger to recharge and maintain your house batteries.

A manual battery charger is designed to recharge a battery and typically produces higher voltages. An automatic or "smart" battery charger is designed to stop charging when a preset current, voltage or time is achieved or to produce different voltages, depending on

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which charging cycle it is in. Battery chargers typically do not have the degree of filtering that a converter or power supply has.

[back to Index]

9.11. What Are Charge Controllers or Voltage Regulators?

Charge controllers and voltage regulators are devices used to control the level or levels, in the case of three and four stage units, of DC voltage from a source of power to the battery or batteries. Typically charge controllers are used to control the output of solar panels and voltage regulators for DC generators or alternators.

[back to Index]

9.12. How Long Will a Deep Cycle Battery Last On a Single Charge?

Discharging, like charging, depends on a number of factors such as the initial State-of-Charge, average Depth-of-Discharge, condition and capacity of the battery, load and temperature. To determine the amount of discharge time (T) for a fully charged battery at 80° F (26.7° C), the simple formula is ampere-hour rating (C) divided by the average load in amps (I) or T = C / I is often used. So, 100-ampere hour battery with an average 5-amp load should last approximately 20 hours (100 AH / 5 amps). The total number of amps that are produced when a fully charged battery is discharged over a 20 hour (C/20) period and to 10.5 volts is the most commonly used specification for expressing the capacity of deep cycle batteries used in most RV and Marine applications; however, five (C/5) or six hour (C/6) for Golf Carts or eight hour (C/8) rates for RV/Marine batteries might be more realistic.

For example, if a deep cycle battery's capacity is rated at 100 ampere hours (AH) at the 20 hour (C/20) rate, it will produce approximately 83 AH at the eight hour (C/8) rate, 63 A in two hours (C/2), and 55 AH in one hour (C/1). This is due to the Peukert Effect.

Repeatedly discharging a wet Low Maintenance deep cycle battery below 20% State-of-Charge (approximately 12.0 volts) or shallow discharges of less than 10% can significantly reduce the number of life cycles. Please see the graph on average Depth-of-Discharge in Section   11.3 . New batteries often require a precondition or "break-in" period of up to 30 cycles before they will produce their rated

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ampere hour capacity. The capacity is reduced over time as the active material flakes (sheds) off the plates and some of the pours fill with hard sulfate.

[back to Index]

9.13. How Can I Reduce Recharging Time?

To reduce the amount of time that your charging system is running, only recharge the battery to 80% State-of-Charge level at an amp hour rate not exceeding the number of amp hours that need to be replaced or C/4 (25% of the AH Capacity), whichever is less. For example, if 50 amp hours has been consumed from a 100 amp hour battery, then you do not want to recharge it at rate any greater than 25 amps in one hour. At a 25 amp charging rate, it should take approximately two hours to get to a 80% State-of-Charge. Please note that it will take almost the same amount of time, at a reduced current, to recharge the battery the remaining 20% to bring it to 100% State-of-Charge as it took to recharge it originally from the 50% to the 80% level. If the battery is recharged to the 80% State-of-Charge level, it should be recharged to 100% at least every 10th cycle or once per week, whichever occurs first.

Using AGM (Ca/Ca) VRLA batteries also will reduce the amount of recharging time because they have a higher acceptance rate than wet lead-acid batteries. (Please see Section   7.1.4 for more information and AGM batteries.)

[back to Index]

9.14. How Can I Adjust the Specific Gravity?

Battery manufacturers set the concentration of the sulfuric acid in the electrolyte of a fully charged wet battery to optimize the capacity, service life, water consumption, use in float applications, high discharge rate capability, battery size and self discharge rate. When the Specific Gravity is increased on purpose or by additives, the following attributes are increased: capacity, service life, water consumption, high discharge rate capability, and self discharge rate. When you decrease the Specific Gravity, the reverse occurs. You might ask why increasing the Specific Gravity on wet starting and motive deep cycle batteries is not a good thing? The answer is that it also accelerates the corrosion of the positive plate grids and connecting straps and you could have a premature battery failure,

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thus effecting overall service life, but clearly there might be some short term gains at the expense of increased watering.

Normally, unless there is a spill, battery acid should never be added to a battery. If the temperature compensated Specific Gravity reading needs to be increased in a cell for whatever reason, remove a small amount of some the existing electrolyte and replace it with fresh battery acid with a 1.300 Specific Gravity. Repeat the process until the cell matches the Specific Gravity readings of the rest of the cells or, if the battery is fully charged, the manufacturer's temperature compensated recommended value for a fully charged cell. If the temperature compensated Specific Gravity reading needs to be decreased in a cell for whatever reason, remove a small amount of some the existing electrolyte and replace it with distilled, deionized or demineralized water. Repeat the process until the cell matches the Specific Gravity readings of the rest of the cells or, if the battery is fully charged, the manufacturer's temperature compensated recommended value for a fully charged cell. Some typical Specific Gravity readings at 80° F (26.7° C) for full charged cells are:

1.300-1.310 for wet motive deep cycle batteries with tubular positive plates

1.267-1.284 for wet motive Deep Cycle batteries with solid lead positive plates

1.260-1.270 for wet Starting batteries with pasted plates

1.215-1.250 for wet stationary Deep Cycle batteries with solid lead positive plates

[back to Index]

9.15. How Do I Recharge Small SLA Batteries?

SLA or Sealed Lead-Acid batteries are part of the VRLA Battery family and are normally under 50 amp hours in capacity. Most of the SLA batteries in use today are AGM (Ca/Ca) because they are less expensive, but there are a few Gel Cell (Ca/Ca) SLA batteries in service. For fast recharging, you should limit the current to 30% of the amp hour capacity of the battery and use an absorption voltage of 2.45 VDC/cell or 14.7 VDC for a 12-volt battery. When the charging current has dropped to .01 times of the amp hour capacity, then the battery is fully charged and the fast charging

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voltage should removed or reduced to a float charging voltage of 2.25 volts/cell or 13.5 VDC for a 12-volt battery.

[back to Index]

9.16. How Do I Recharge Unevenly Discharged or Non-identical Batteries at the Same Time?

If discharging the batteries unevenly or using non-identical batteries has to occur, then use an isolated multi-bank charger, single

If discharging the batteries unevenly or using non-identical batteries has to occur, then use an isolated multi-bank charger, single bank charge with an external diode isolator (adjusted for the voltage loss), or combiner to recharge the batteries at the same time.

10. WHAT CAUSES MY BATTERY TO DRAIN OVERNIGHT?

Parasitic (or ignition key off) drain is the cumulative load produced by electrical devices, for example, emissions computers, clocks, security alarms, radio presets, etc., that operate continuously after the engine is stopped and the ignition key has been switched off. Normal parasitic loads are below 75 milliamps (.075 amps). When the parasitic load is greater than 75 milliamps (.075 amps), batteries will drain more quickly. Glove box, trunk, and under hood lights that do not automatically turn off when the door is closed or shorted diodes in alternators are the most common offenders. Cooling fans, power seat belt retractors, radios and dome lights left on, alarm systems, and electric car antennas have also caused batteries to drain overnight. Leaving your headlights on will generally discharge a fully charged car battery within four hours.

It is highly recommended, especially if you are using a sealed wet "Maintenance Free" (Ca/Ca) battery, that you allow it to thaw if frozen, fully recharge it in a well ventilated area with an external battery charger, remove the surface charge, and load tested both the battery and the charging system for latent damage from the deep discharge. You could have a damaged or bad battery. If the alternator is warm when the engine is cold, then check for a shorted diode in the alternator.

Below are some methods that are used to test the parasitic load with the battery recharged, engine NOT running, under hood light disconnected, all accessories switched off, and the vehicle doors closed:

Connect a small 12-volt bulb across the positive and negative battery terminals to test the bulb and the

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battery. If it glows brightly, then remove the negative battery cable and connect the bulb in series between the negative battery cable terminal clamp and the negative battery terminal. If the bulb continues to glow brightly, then start removing fuses or connections to the positive battery post one-at-a-time until the offending electrical component is identified by the bulb dimming.

A better approach is to use a DC ammeter, for example a Fluke 175, inserted in series with the negative battery cable terminal clamp and the negative battery terminal or a clamp-on DC ammeter, like a Fluke 336 or i410 around the negative battery cable. Starting with the highest scale, determine the current load. If the load is above 75 milliamps (.075 amps) after the initial surge, then start removing fuses or connections to the positive battery post one-at-a-time until the offending electrical component is identified by the parasitic load dropping to within 75 milliamps (.075 amps).

Additional troubleshooting techniques can be found in a guide from Exide at http://www.exide.com/products/trans/na/battery_care/electrical_parasitic_load.pdf.

11. CAN I INCREASE THE LIFE OF MY BATTERY?

The most important consideration in increasing the overall service life of a lead-acid battery is preventive maintenance. Please see Section   3 for more information on preventive maintenance. The typical life of a good quality, well maintained and properly charged battery is:

EXPECTED BATTERY SERVICE LIFE

Pasted Plate Car (used as a Deep Cycle)

0 to 12 months

Pasted Plate Car 4 to 5 years

Pasted Plate Marine/RV

2 to 4 years

Golf Cart (Motive) Deep Cycle

3 to 5 years

"L-16" (Motive) Deep 7 to 10

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Cycle yearsGel Cell (Ca/Ca) VRLA (Motive) Deep Cycle

to 8 years

AGM (Ca/Ca) VRLA (Motive) Deep Cycle

2 to 10 years

Ni-Cad (Motive) Deep Cycle

to 10 years

Calcium Telecommunications

(Stationary) Deep Cycle

to 10 years

Fork Lift (Motive) Deep Cycle

10 to 20 years

Manchex Industrial (Motive) Deep Cycle

to 15 years

Wet Standard (Sb/Sb) Industrial (Stationary)

Deep Cycle

to 20 years

Ni-Fe (Stationary) Deep Cycle

to 20 years

Here are some tips to increase car or deep cycle battery service life:

11.1. Protecting your car battery from high underhood temperatures with a heat shield or case, keeping it full charged at all times, and maintaining it are the easiest ways to extend it's life. In hot climates and during summer, the electrolyte levels need to be checked more frequently. In a study conducted by the Society of Automotive Engineers (SAE), the underhood temperature has increased more than 30% since 1985. For every increase of 18° F (10° C) above 77° F (25° C), positive grid corrosion or self-discharge rate is doubled.

Chrysler studies have shown that relocating the battery outside the engine compartment has increased the average OEM battery life by eight months. Relocating the starting battery to the trunk or passenger compartment, as Mazda did in their Miata a number of years ago, is becoming more popular by the car manufacturers to protect the starting battery from the high underhood temperatures. However, use sealed AGM (Ca/Ca) or Gel Cell (Ca/Ca) VRLA type batteries because they normally do not produce gas when recharged or use wet batteries vented to the outside. If you use a Gel Cell (Ca/Ca) VRLA as a starting battery, you might have to

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lower the charging system voltages because they are very critical and to keep from overcharging the battery.

For motive and stationary deep cycle batteries, temperature is equally as important for extending the service life of the battery or battery bank. Common sense and chemical intuition suggest that the higher the temperature, the faster a given chemical reaction will proceed. Quantitatively this relationship between the rate a chemical reaction proceeds and its temperature is determined by the Arrhenius equation. Battery life, due to positive grid corrosion, is reduced by 50% for every 18° F (10° C) rise in ambient temperature over 77° F (25° C).

11.2. Periodically check the State-of-Charge of car batteries. Based on your driving habits, some vehicle charging systems undercharge the battery causing an accumulation of lead sulfate known as sulfation. This sulfation reduces the capacity of the battery. If the battery is not fully charged, recharge it periodically with an external battery charger matched to the battery type. Please see Section   9 for more information on charging and chargers and Section   16 for more information on sulfation.

In addition to temperature, car battery life and the number of charge and discharge cycles is dramatically influenced by the average State-of-Charge (SoC) as reflected in the following graph:

Car Battery Life

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[Source: Adverc Battery Management]

If possible in a well ventilated area and at room temperature, recharge a deep cycle battery each day it is used and as soon as possible after each use. The best way to prevent permanent lead sulfation when a starting or deep cycle battery (or battery bank) is not in use, is to maintain it's State-of-Charge at 100% by continuous float charging. If continuous float charging is not possible, recharge before the State-of-Charge drops below 80%. Permanent sulfation kills approximately 85% of all deep cycle and starting lead-acid batteries not in weekly service. During hot weather, try and drive your vehicle at least once per week and in cold weather, once every two weeks. This is because batteries are perishable and the vehicle's parasitic (ignition key off) load and the natural self-discharge drain the battery. When the battery is not fully charged, sulfation occurs and the lead sulfate crystals will accumulate, harden and reduce the capacity of the battery. The same phenomenon occurs when a battery is undercharged or when electrolyte stratification occurs in larger wet lead-acid batteries. Please see Section   16. for more information on sulfation.

11.3. Reducing the average DoD (Depth-of-Discharge) and the number of discharge/charge cycles, by proper deep cycle battery or battery bank sizing will significantly increase a deep cycle battery service life. For example, a pasted plate wet battery with an average of 50% DoD will last twice as long or more as if it is has an 80% average DoD. A 20% DoD average battery can last up to five times longer than one with a 50% DoD

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average. Wet Golf cart batteries will typically have an average 225 cycles at 80% DoD and 750 cycles at 50% DoD. For more information of the "50%   Rule" , please see Chris Gibson's article on http://www.smartgauge.co.uk/50percent2.html. Always avoid Depth-of-Discharges that are greater than 80%. The "sweet spot" (optimum DoD for the greatest amount of power produced over the service life) is generally somewhere between 20% DoD and 60% DoD average. For the AGM (Ca/Ca) VRLA battery example below the "sweet spot" is approximately 22.5% DoD based on the greatest amount of power produced.

AGM (Ca/Ca) Life Cycles vs. Percent Depth-of-Discharge (DoD)

[Source: Concorde]

11.4. If required, equalize wet (flooded) and some AGM (Ca/Ca) batteries. Equalizing can also prevent electrolyte stratification, which can cause sulfation. Please see Section   9. for more information on equalizing batteries.

11.5. In extremely cold climates, keep the car battery continuously fully charged when not in use, the engine and battery warm, and use low viscosity synthetic engine oil. AGM (Ca/Ca) VRLA or Ni-Cad batteries work better in sub-zero temperatures than wet lead-acid batteries.

11.6. In hot climates use the "hot climate or "South" versions of car batteries. They have special plate and connecting strap formulations, lower Specific Gravity levels or increased the amounts of electrolyte to provide more "cooling" for longer service life. Using non-sealed Low Maintenance

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(Sb/Ca) car batteries is encouraged because you can add water. "Watering" is required more often in hot climates and add only distilled, demineralized or deionized water or, in a emergency, rain water. The plates must be covered at all times to prevent an internal battery explosion or sulfation. Do not overfill, and keep the top of the battery clean. Do NOT add electrolyte (battery acid) to a battery unless some electrolyte has spilled. If the Specific Gravity levels are increased beyond the battery manufacturer's recommended limit, the battery will exhibit a higher capacity level, but will require more maintenance and a have shorter overall service life. Please see Section   9.14 for more information on adding electrolyte or adjusting Specific Gravities.

11.7. Turning off all unnecessary accessories, rear window heater, climate control, and lights before starting your car will significantly decrease the load on the battery while cranking, especially when it is extremely cold.

11.8. Reducing the parasitic (key-off) load to below 75 milliamps.

11.9. In cold climates, increasing the diameter of the battery cables will reduce the voltage loss.

11.10. Never discharge any 12-volt lead-acid battery below 10.5 volts because it can damage the battery. An adjustable low voltage disconnect set for an 80% Depth-of-Discharge (DoD) or less can limit the maximum DoD and protect the batteries and electrical appliances. Leaving your lights or other accessories on and fully discharging a car battery can ruin it due to "cell reversal", especially if it is a sealed, wet Maintenance Free (Ca/Ca) type. Deep discharges in freezing weather will cause the battery to freeze and the expansion of the electrolyte can damage the plates, separators or even crack the battery case. If freezing should occur, you must let your battery thaw, physically inspect case for leakage, fully recharge it with a "smart" or "automatic" external charger matched the the battery type in a well ventilated area, remove the surface charge, and load test the battery and charging system to determine if there is any latent or permanent damage.

11.11. For vehicles not used weekly or driving habits that cause undercharged batteries, continuously float charge the car battery or fully recharge it periodically to remove the accumulated lead sulfate. Please see Section   13 for more information on storing batteries and Section   16 for more information on sulfation.

11.12. Provide adequate ventilation. High ambient temperatures above 80° F (or 26.7° C) will shorten battery life because it increases positive grid corrosion, growth and VRLA "thermal runaway".

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11.13. Recharging slowly using the battery manufacturer's recommended temperature compensated voltages and procedures.

11.14. Avoid shallow (less than 10% DoD) discharges of deep cycle batteries because lead dioxide builds up on the positive plates. In other words, you should discharge a deep cycle battery between 90% and 20% Depth-of-Discharge.

11.15. Use batteries with thicker pasted or solid plates, thicker or tapered grids, and reduce the number of discharge-charge cycles. Each cycle removes a microscopic layer from the grid and eventually the upper portion of the grid can not carry the current.

11.16. Apply the correct battery type for the application, that is, starting for starting applications, motive deep cycle batteries for motive, and stationary deep cycle batteries for stationary applications. Please see Section   7.1 for more information on battery typpe

12. WHAT ARE THE COMMON CAUSES OF PREMATURE BATTERY FAILURES?

Normally, premature battery failures are caused by one or more of the failures listed below with water loss and sulfation the main offenders. Prior to 1980, plate or grid shorts were the most common failure. Since then the manufacturers have significantly improved the life expectancy by using better separators, plate alloys to reduce corrosion, and heat shields. Relocating starting batteries to the passenger compartment (or trunk) also has considerably decreased premature battery failures. Batteries that have been in use for longer periods of time will typically fail from multiple causes. All batteries will fail at some point in time from old age (positive plate shedding of active material or grid corrosion).

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[Source: Interstate Batteries]

12.1. For wet car batteries, lack of preventive maintenance, high underhood heat, fast recharging (greater than C/4), or overcharging causes a loss of water, which accounts for over 50% of the failures. For wet motive and stationary deep cycle batteries, water loss due to the lack of preventive maintenance or overcharging is the main culprit. Please see Section   3 for more information on preventive maintenance.

12.2. Sulfation from water loss, undercharging, electrolyte stratification (especially in larger batteries over a 100 amp hours), using tap water, excessive temperatures, or prolonged periods of non-use account for approximately 85% of the deep cycle and starting battery failures that are not used weekly (or bi-weekly in colder climates). Some vehicle charging systems based on driving habits (short trips or high loads) leave the car battery constantly undercharged and sulfated. Please see Section   16 for more information on sulfation.

12.3. Battery post or terminal corrosion, which cause charging and discharging problems. Please see Section   3 for more information on preventive maintenance.

12.4. High ambient temperatures above 77° F (25° C) causing accelerated positive grid growth or corrosion, increased self-discharge, or thermal runway in AGM (Ca/Ca) and Gel Cell (Ca/Ca) VRLA batteries. For every increase of 18° F (10° C) above 77° F (25° C), the battery's life is cut in half due to positive grid corrosion or the self-discharge rate is doubled.

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12.5. Excessive deep discharges below 10.5 volts, such as leaving your vehicle's lights on.

12.6. Misapplication, for example, using a starting battery in a deep cycle application, a motive deep cycle battery instead of a stationary for a UPS, or an undersized battery (or battery bank) that causes discharges greater than the battery was designed for or will not produce enough capacity.

12.7. Plate-to-strap shorts due to excessive vibration caused by loose hold down clamps or vehicle running on rough surfaces or freezing

13. HOW CAN I STORE (OR WINTERIZE) BATTERIES?

INDEX:

13.1. How Do I Prevent Permanent Sulfation?

13.2. So How Do I Store (Or Winterize) My Battery?

All lead-acid batteries are perishable. If not used weekly, people kill more deep cycle and power sport batteries with bad charging and maintenance practices, than batteries will die of old age!

When a lead-acid battery is discharged, soft lead sulfate crystals are formed in the pores and on the surfaces of the positive and negative plates. When left in a discharged condition or excessive high temperatures, is continually undercharged, or the electrolyte level is below the top of the plates or stratified, some of the soft lead sulfate re-crystallizes into hard lead sulfate. These crystals cannot be reconverted during subsequent recharging. This creation of hard crystals is commonly called permanent "sulfation". It is the leading cause and accounts for approximately 85% of the premature failures of lead-acid batteries not used on weekly basis. The longer sulfation occurs, the larger and harder the lead sulfate crystals become. The positive plates will turn a light brown and the negative plates will be dull, off-white. These permanent crystals lessen a battery's capacity and ability to be recharged or hold a charge. Sulfation primarily occurs in deep cycle and power sport batteries that are typically used for short periods and then are stored for long periods where they slowly self-discharge. Whereas a car or motorcycle starting battery is normally used several times a month, so permanent sulfation rarely becomes a problem unless it is unused or stored for long periods.

While a battery is in storage or not being used, the discharge is a result of parasitic load or natural self-discharge. Parasitic load is the constant electrical load present on a battery while it is installed in a vehicle even when the ignition

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key is turned off. The load is from the continuous operation of electrical appliances, such as an emissions computer, clock, security system, maintenance of radio station presets, etc. While disconnecting the negative battery cable will eliminate the parasitic load, it has no affect on the natural self-discharge of the battery. Thus, permanent sulfation can be a huge problem for lead-acid batteries while sitting for long periods on a dealer's shelf, in a basement, cellar, barn or garage, or in a parked vehicle, especially in hot temperatures.

13.1. How Do I Prevent Permanent Sulfation?

Please see Section   16.2 for more information on preventing sulfation.

[back to Index]

13.2. So How Do I Store (Or Winterize) My Battery?

Batteries naturally self-discharge 1% to 60% per month (depending on the battery type and temperature) while not in use. Sulfation will begin occurring whenever the Depth-of-Discharge (DoD) increases above 0% in other words, when the battery is not fully charged. Please see Section   16 for more information on sulfation. Cold will slow the process down and heat will increase it up. Storing batteries under 250 AH on concrete floors will not normally cause them to naturally self-discharge faster. Please see Section   14.1 for more information on this myth. Below are six simple steps while your batteries are not in use to protect them from permanent sulfation and premature failure.

13.2.1. Physically inspect for leakage or damaged cases, remove any corrosion, clean and dry the tops of the batteries to remove possible discharge paths from dried battery electrolyte, and clean the terminals. If the battery is in a vehicle, remove the negative connection from the battery to eliminate the additional parasitic (key off) discharge.

13.2.2. If the battery has filler caps, check the electrolyte (battery acid) level in each cell. If required, add only distilled, deionized or demineralized water to the recommended level, but do not overfill.

13.2.3. Fully charge and equalize wet (flooded) batteries, if required, using the procedures in Section   9 and recheck the electrolyte levels when the battery cools.

13.2.4. Store in a cold dry place, but not so that it will freeze, and where it can be easily recharged. The freezing point of a battery is determined

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by the SoC and the higher it is, the lower the freezing temperature. Please see the Electrolyte Freeze Points Table in Section   4.4.1 . Based on the battery type you are using, connect a "smart", microprocessor based three-stage, four-stage charger or a voltage regulated float charger to continuously "float" charge your battery. Do not use a cheap, unregulated "trickle" charger or a manual two-stage charger which was not designed for "float" charging or you will overcharge your battery. A less desirable alternative to float charging would be to periodically test the State-of-Charge using the procedure in Section   4 . When it is 80% or below, recharge using the procedures in Section   9 . The frequency of testing and recharging will depend on the ambient storage temperature.

AGM (Ca/Ca) VRLA BATTERY FLOAT CHARGING VOLTAGE

TEMPERATURE IN DEGREES C (F)

[Source: Concorde]

13.2.5. Periodically test the State-of-Charge (SoC) and ensure that the electrolyte is at the proper levels.

13.2.6. Float or periodic recharging will prevent batteries from freezing. An Electrolyte Freeze Points at Various States-of-Charge for a Wet Lead-

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Acid Battery table indicates the temperature when the electrolyte will freeze.

13.2.7. When you remove the batteries from storage, charge and equalize, if required, using the battery manufacturer's recommended charging procedures or, if not available, the one in Section   9.

14. WHAT ARE THE MYTHS ABOUT BATTERIES?

INDEX:

14.1. MYTH: Storing batteries on a concrete floor will discharge them.

14.2. MYTH: Driving a car will fully recharge a battery.

14.3. MYTH: A battery will explode.

14.4. MYTH: A battery will lose its charge sitting in storage.

14.5. MYTH: Wet "Maintenance Free" (Ca/Ca) batteries never require maintenance.

14.6. MYTH: Test an alternator by disconnecting the battery with the engine running.

14.7. MYTH: Conditioners, aspirins or additives will revive sulfated batteries.

14.8. MYTH: On really cold days turn your headlights on to "warm up" the battery up before starting your engine.

14.9. MYTH: Car batteries last longer in cold climates than in hot ones.

14.10. MYTH: Charging cables will start your car.

14.11. MYTH: A larger capacity battery will damage my car.

14.12. MYTH: Lead-acid batteries have memories.

14.13. MYTH: Bad batteries can harm the charging system or starter.

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14.14. MYTH: Once formed, batteries will not change polarity.

14.15. MYTH: Do not use tap water to refill batteries.

14.1. MYTH: Storing batteries on a concrete floor will discharge them.

False! All lead-acid batteries will naturally self-discharge which can result in loss of capacity from sulfation. The rate of self-discharge is most influenced by the temperature of the battery's electrolyte and the chemistry of the plates. This self-discharge is often mistaken for concrete floor causing the battery to drain. Some experts believe that storing car or deep cycle batteries on a colder concrete floor might actually slow down the self-discharge (leakage) rate because the floor acts as a heat sink and cools the battery. (Please see Section   13 for more information on storing batteries and Section   1 for more information on sulfation.

In the early 1900s, when battery cases were made of porous materials such as tar-lined wood boxes, storing batteries on concrete floor would accelerate their natural self-discharge due to external leakage. Modern battery cases are made of polypropylene or hard rubber. These cases are sealed better, so external leakage-causing discharge is no longer a problem, provided the top of the battery is clean and free from wet or dried electrolyte and the same temperature as the floor.

Large differences in temperature could cause electrolyte stratification within very large batteries (>250 AH) which could accelerate it's internal "leakage" or self-discharge if the battery is sitting on an extremely cold concrete, stone or steel floor in a warm room, boat or submarine. Stirrers or bubblers are often used on these types of large batteries to keep the electrolyte from stratifying. Undercharging will also cause electrolyte stratification, which can also result in loss of capacity from sulfation.

[back to Index]

14.2. MYTH: Driving a car will fully recharge a battery.

False! There are a number of factors affecting a vehicle charging system's ability to recharge a battery, such as how much power and charging voltage from the alternator is diverted to the battery, how long the power is available, and the temperature. Generally, idling the engine or short stop-and-go trips during bad weather or at night will not fully recharge a car battery or will leave your battery

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undercharged which causes sulfation. When a dead battery needs to be recharged, it is best to use an external battery charger because you could overheat and damage your vehicle's charging system and your will save a lot of gas and wear and tear on your engine. Please see Section   5 and Section   9 for more information on vehicle charging systems and charging.

If jump starting is required to start an engine, the battery should be fully charged by an external charger and then tested for latent damage. Assuming that a car battery has a 50 amp hour capacity and the vehicle's charging system is capable of recharging it at 50 amps at highway speeds, it would take approximately 120 minutes to fully recharge a good battery. If the battery is frozen, install another fully charged battery until the original battery can be thawed out, fully recharged and tested or tow the vehicle to a heated garage. Vehicle charging systems are not designed to recharge fully discharged batteries and doing so may damage the stator windings or the diodes (from overheating).

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14.3. MYTH: A battery will explode.

True! Charging a wet lead-acid battery naturally produces hydrogen and oxygen gasses as electrolysis of the water occurs and needs to occur in well ventilated areas. While spark retarding vent caps help prevent external battery explosions, sparks occur when jumping, connecting or disconnecting charger or battery cables and ignite the gas causing an explosion. From the U.S. Department of Energy, DOE-HDBK-1084-95, "Precautions must be routinely practiced to prevent explosions from ignition of the flammable gas mixture of hydrogen and oxygen formed during overcharge of lead-acid cells. The maximum rate of formation is 0.42 L of hydrogen and 0.21 L of oxygen per ampere-hour overcharge at standard temperature and pressure. The gas mixture is explosive when hydrogen in air exceeds 4% by volume." Less common internal explosions usually occur while starting the engine or using the battery and normally just blow the filler caps or cover off the battery and splatter electrolyte all over the engine compartment or battery box.

The most probable cause of internal battery explosions are from a combination of low electrolyte levels below the plates in the battery, a low resistance bridge is formed between or across the top of the plates, and a build up of hydrogen gas in the cell. The low resistive

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bridge is called "treeing" between the positive and negative plates. When current flows in the battery, a spark occurs and ignites the residual gas in one or more of the cells. A second possible cause is a manufacturing defect in the weld of one of the plate connecting straps causing a spark igniting the residual gas. Another source of internal battery explosions are caused from direct electrical shorts across the battery's terminals. The battery rapidly over heats form the high current and can explode. The largest number of internal battery explosions occur in hot climates due to the loss of water while starting the engine. Most internal battery explosions could have been prevented if the plates were always covered with electrolyte. Please see Section   3 for more information on preventive maintenance.

A less common form of internal battery explosion occurs when a dead short is applied across the battery terminals or the battery is in a fire.

 [Source: Popular Mechanics]

Periodic preventive maintenance (Please see Section   3 .), working on batteries in well-ventilated areas, or using sealed AGM (Ca/Ca) or Gel Cell (Ca/Ca) type batteries can significantly reduce the possibility of battery explosions. To neutralize residual battery acid,

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be sure to thoroughly wash the engine compartment and the back of the hood with a solution of one-pound baking soda (bicarbonate of soda) to one gallon of warm water and rinse thoroughly with water. While not fatal, each year battery explosions cause thousands of eye and burn injuries from the electrolyte (battery acid). According to PREVENT BLINDNESS AMERICA, in 2003 nearly 6,000 motorists suffered serious eye injuries from working around car batteries. Should a battery explosion occur and battery electrolyte (battery acid) gets in someone's eyes, flush them out with any drinkable liquid immediately because SECONDS count, continue flushing with water for at least 15 minutes, and seek immediate medical attention.

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14.4. MYTH: A battery will lose its charge sitting in storage.

True! Depending on the type of battery and temperature, batteries have a natural self-discharge or internal electrochemical "leakage" at a 1% to 60% rate per month. Over time the battery will become sulfated and fully discharged which make it more susceptible to freezing. Higher temperatures will significantly accelerate this process. A battery stored at 95° F (35° C) will self-discharge twice as fast than one stored at 75° F (23.9° C). Leaving a battery in a vehicle can increase the discharge of battery due to the additional parasitic (ignition key-off load), unless the ground, normally negative, cable is disconnected from the battery. (Please see Section   15 and Section   16 for more information on parking times and sulfation.)

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14.5. MYTH: Wet "Maintenance Free" (Ca/Ca) batteries never require maintenance.

False! The term "Maintenance Free" generally refers to a wet, sealed lead-acid car and deep cycle batteries with calcium positive and negative plates. (Please see Section   7.1.3 for more information on these types of batteries.) In hot climates, the water is lost due to evaporation caused by high underhood temperatures and normal charging. Water can also be lost due to excessive charging voltage or charging currents. Using non-sealed wet Low Maintenance (Sb/Ca) batteries (with filler caps) is encouraged in hot climates so distilled, deionized or demineralized water can be added when this

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occurs. (Please see Section   3. for other preventive maintenance procedures that should be performed on wet "Maintenance Free" (Ca/Ca) batteries.)

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14.6. MYTH: Test an alternator by disconnecting the battery with the engine running.

False! A battery acts like a voltage stabilizer or filter to the pulsating DC produced by the alternator. Disconnecting a battery while the engine is running could destroy the sensitive electronic components connected to the electrical system such as the emission computer, radio, audio system, cell phone, alarm system, etc., or the charging system, especially with internal voltage regulators, because the peak voltage can rise to 40 volts or more. In the 1970s, removing a battery terminal was an accepted practice to test charging systems of that era. That is not the case today. Static electricity and spikes from connecting and disconnecting batteries or test equipment could also damage sensitive electronic components.

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14.7. MYTH: Conditioners, aspirins or additives will revive sulfated batteries.

False! Most battery experts agree that there is no evidence that conditioners, additives or aspirins provide any long-term benefits. Short term gains are achieved by increasing the acidity (Specific Gravity) of the battery, which could increase the Amp Hour capacity, but increase the water consumption and positive grid corrosion and it will also decrease the overall service life of the battery. After a heavy discharge, allowing a battery to rest will regain some of its capacity as the electrolyte has an opportunity to diffuse in the pores of the plates. If the Specific Gravity of a cell requires adjustment, please see Section   9.14 .

This controversy between the additive manufacturers, battery manufacturers, and independent electrochemists has been going on for over 50 years as demonstrated in this AD-X2 Battery Additive, From a Trickle to a Torrent article form the National Institute of Standards and Technology (NIST) Museum.

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14.8. MYTH: On really cold days turn your headlights on to "warm up" the battery up before starting your engine.

False! While there is no doubt that turning on your headlights will increase the current flow in a car battery, it also consumes valuable capacity that could be used to start the cold engine. Therefore, this is not recommended. For cold temperatures, externally powered temperature compensated battery "float" chargers, warmers or blankets, and engine block heaters are highly recommended if the vehicle can not be parked in a heated garage. AGM (Ca/Ca) and Ni-Cad batteries will perform better than wet lead-acid batteries in extremely cold temperatures.

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14.9. MYTH: Car batteries last longer in cold climates than in hot ones.

True! Car batteries last an average of two thirds as long in hot climates as cold ones. Heat kills car batteries, especially sealed Maintenance Free (Ca/Ca) batteries, and cold reduces the battery's starting capacity. (Please see Section   11.1 for more information on increasing battery life.)

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14.10. MYTH: Charging cables will start your car.

False!The cigarette lighter charging cable's advertising states "charges weak batteries in minutes." There is little doubt that charging cable products will certainly increase the charge in your car battery if you have enough time and your battery is in good condition. Cigarette lighters are normally fused at 10 amps, so to be safe they probably limit current to flow less than the fuse size. Given the diameter of the wire used in the cable, the amount might be even less.

They work by applying higher voltage from the vehicle with the good battery to "charge" the bad one. In order to charge a battery the charging voltage needs to be approximately two volts greater than the battery voltage to overcome the internal resistance. Now

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let's assume it is a hot day and that you need just of 3% of the battery's capacity to start the engine from a 40 amp hour battery. This means you will need at least 7.5 amps for 10 minutes to flow from the good battery with the engine idling to the bad one. Now let's also assume that it is below freezing and you have left your lights on. You will need at least 50% capacity or 20 amp hours to start the vehicle. This will take over two hours to partially charge the dead battery. Using jumper cables with the engine running at high idle will partially charge a dead battery much faster. Please see Section   6 for jump starting, but be sure the battery is not frozen or the case is not cracked.

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14.11. MYTH: A larger capacity battery will damage my car.

False!A starter motor will only use a fixed amount of current from the battery, based on the resistance of the motor. A larger Cold Cranking (CCA), Reserve Capacity (RC) or Amp Hour (AH) capacity battery supplies only what is required. It will not damage your vehicle; however, using batteries with higher or lower voltage or physically too high could potentially cause harm.

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14.12. MYTH: Lead-acid batteries have memories.

False! Lead-acid batteries do not have the "memory effect" mistakenly identified with first generation Ni-Cad batteries; however, continuous undercharging will lower the capacity of the battery over time due to the accumulation of permanent lead-sulfate or "sulfation". Deep discharges below twenty percent State-of-Charge (approximately 12.0 volts) can damage batteries and will shorten their service lives.

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14.13. MYTH: Bad batteries can harm the charging system or starter.

True! A bad or weak starting battery causes additional stress on a charging system, starter motor or starter solenoid. It can cause premature failures due to compensating for the voltage or current. If

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you replace a battery, alternator, voltage regulator or starter, you should test the other components for damage and repair or replace them as required.

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14.14. MYTH: Once formed, batteries will not change polarity.

False! If a battery is fully discharged and continues to have a load, for example leaving the headlights on, it is possible for one or more cells to reverse polarity. When the battery has been recharged with reversed polarity the polarity can change. This is referred to as "cell reversal". To change polarity, fully discharge the battery and recharge it with the correct polarity.

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14.15. MYTH: Do not use tap water to refill batteries.

True! Use only distilled, deionized or demineralized water to replace the lost water in batteries. This is because using tap or reverse osmosis water from residential systems can produce calcium or magnesium sulfate crystals that can fill the pores and coat the plates. In other words, wet batteries will have a longer service life if you do not use tap water. In an emergency, use rain water because rain water does not contain calcium or magnesium.

15. HOW LONG CAN I PARK MY VEHICLE?

The amount of time, usually referred to as "airport", "garage", or "storage" time, that you can leave your vehicle parked and still start your engine is dependent on such things as the battery's initial State-of-Charge (SoC), the Reserve Capacity (or amp hour capacity), the amount of natural self-discharge and parasitic (ignition key off) load, temperature and battery type (plate chemistry). Car manufacturers normally design for at least 14 days or more "airport" time; based on a fully charged battery in good condition, moderate weather, and no additions to the original car's parasitic load (for example, an after market alarm system). The number of days will vary based on the temperature. When a battery drops below 100% SoC, sulfation starts slowly occurring, and this will reduce the capacity of the battery and if left unchecked, will kill the battery.

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If you leave your vehicle parked for more than two weeks, then you have several options:

15.1. The best long term (over one month) option is to continuously float charge your car battery by connecting a "smart" battery charger or a voltage regulated float charger because it will keep the battery fully charged, thus eliminating sulfation. If there is no AC power available, use a five watt (or greater) solar float charger. These options will allow you to park you vehicle indefinitely, but the battery should be checked periodically. You will need a "float" charging voltage between 13.2 and 13.8 VDC at 80° F (26.7° C) and at least .5 amps (500 milliamps) to overcome the vehicle's parasitic load and the natural self-discharge of the battery. Do not use a cheap "trickle" charger, because it will overcharge your battery and dry out the electrolyte.

15.2. Disconnect the grounded battery cable (which is normally the NEGATIVE (-) cable) to remove the parasitic load, but be sure that you have saved any security codes or radio stations presets that will have to be reprogrammed, but the battery's natural self-discharge will continue. This option will work from one month to six months depending battery type and temperature.

15.3. Replace the battery with the largest AGM (Ca/Ca) or Spiral Wound AGM VRLA battery that will fit, e.g., an Optima or Exide Select Orbital, with very low self-discharge rates. For periods greater than two months, also disconnect the grounded battery cable to remove the parasitic load. This option will work for six months to twelve months depending battery type and temperature.

15.4. Install a battery with a larger reserve capacity or connect an identical battery in parallel, but the battery's natural self-discharge will continue. For periods greater than two months, also disconnect the grounded battery cable to remove the parasitic load. This option will work for two months to twelve months depending battery type and temperature.

15.5. Replace the battery when you are ready to drive the vehicle again, especially if the battery is over three years old and in a hot climate.

15.6. Have someone drive your car during the day at highway speeds every two weeks for at least 15 minutes to keep the battery charged.

15.7. Jump start the battery and hope that there is no latent damage.

15.8. Install a low voltage disconnect. This is especially helpful if the driver forgets to turn the headlights off

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16. HOW CAN I REVIVE A SULFATED BATTERY?

INDEX:

16.1. How Can I Tell If my Battery Has Permanent Sulfation?

16.2. How Do I Prevent Permanent Sulfation?

16.3. How Do I Recover Sulfated Batteries?

16.4. Where Can I Find Additional Information On Sulfation?

People kill more deep cycle batteries with poor charging practices, than die of old age!

Lead sulfation actually starts when you remove the charging voltage a full charged lead-acid battery. The lead sulfate crystals are converted back to lead during the normal charging cycle. The real question is, if all of the lead sulfate crystals are not turned back into lead, how long does it take before they become so hard that they can not be converted? The answer is that varies--it could be weeks or months and depends on a number of factors such as the quality of the lead, temperature, plate chemistry, porosity, Depth-of-Discharge (DoD), electrolyte stratification, and so on.

During the normal discharge process, lead and sulfur combine into soft lead sulfate crystals are formed in the pores and on the surfaces of the positive and negative plates inside a lead-acid battery. When a battery is left in a discharged condition, continually undercharged, or the electrolyte level is below the top of the plates or stratified, some of the soft lead sulfate re-crystallizes into hard lead sulfate. It cannot be reconverted during subsequent recharging. This creation of hard crystals is commonly called permanent or hard "sulfation". When it is present, the battery shows a higher voltage than it's true voltage; thus, fooling the voltage regulator into thinking that the battery is fully charged. This causes the charger to prematurely lower it's output voltage or current, leaving the battery undercharged. Sulfation accounts for approximately 85% of the lead-acid battery failures that are not used at least once per week. The longer sulfation occurs, the larger and harder the lead sulfate crystals become. The positive plates will be light brown and the negative plates will be dull, off white. These crystals lessen a battery's capacity and ability to be recharged. This is because deep cycle and some starting batteries are typically used for short periods, vacations, weekend trips, etc., and then are stored the rest of the year to slowly self-discharge. Starting batteries are normally used several times a month, so sulfation rarely becomes a problem unless they are undercharged or the plates are not covered with electrolyte.

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As a consequence of parasitic load and natural self-discharge, permanent sulfation occurs as the lead-acid battery discharges while in long term storage. (Parasitic load is the constant electrical load present on a battery while it is installed in a vehicle even when the power is turned off. The load is from the continuous operation of appliances, such as a clock, security system, maintenance of radio station presets, etc.) While disconnecting the negative battery cable will eliminate the parasitic load, it has no effect on the natural self-discharge of a car battery. Self-discharge is accelerated by temperature. For batteries that are over 77° F (25° C), the self-discharge rate doubles with a 18° F (10° C) rise in temperature. Thus, sulfation can be a huge problem for lead-acid batteries not being used, sitting on a dealer's shelf, or in a parked vehicle, especially in HOT temperatures.

Car and deep cycle lead-acid batteries are perishable!

16.1. How Can I Tell If my Battery Has Permanent Sulfation?

Chances are that your battery has some permanent sulfation, if it will not "take" or "hold" a charge and exhibits one or more of the following conditions:

If your wet (flooded) Standard (Sb/Sb) or wet (flooded) Low Maintenance (Sb/Ca) battery has been not been recharged for over three months, especially if the temperature in the storage area was consistently over 77° F (25° C). [Six months for wet "Maintenance Free" (Ca/Ca) or one year for AGM (Ca/Ca) or Gel Cell (Ca/Ca)VRLA.]

While recharging in a well ventilated area, the ammeter does not drop to below 2% (C/50) of the expected time to recharge the battery and the battery is warm or hot. For example, if you have a fully discharged 50 Amp Hour battery and a ten amp charger, a discharged battery should be fully charged within 10 hours (2 x 50 AH / 10 amps = 10 hours).

If the Specific Gravity is low in all cells after the battery has been on a charger for a long time.

If the temperature compensated absorption charging voltage is correct and the battery is gassing or boiling excessively.

Poor performance or low capacity. When the SoC measured by a hydrometer, which is

more accurate, does not materially agree with the SoC measured by a digital voltmeter

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16.2. How do I prevent permanent sulfation?

The best way to prevent sulfation is to keep a lead-acid battery fully charged because lead sulfate is not formed. This can be accomplished in three ways. Based on the battery type you are using, the best solution is to use an external charger in a well ventilated area that is capable of delivering a continuous, temperature compensated "float" charge at the battery manufacturer's recommended float or maintenance voltage for a fully charged battery. For 12-volt batteries, depending on the battery type, usually have fixed float voltages between 13.1 VDC and 13.9 VDC, measured at 80° F (26.7° C) with an accurate (.5% or better) digital voltmeter. [For a six-volt battery, measured voltages are one half of those for a 12-volt battery.] This can best be accomplished by continuously charging using a three-stage for AGM (Ca/Ca) or Gel Cell (Ca/Ca) VRLA batteries or four stage for wet (flooded) batteries, "smart" microprocessor controlled charger. If you already have a two-stage charger, then use a voltage-regulated "float" charger or battery "maintainer", set at the correct temperature compensated float voltage to "float" or maintain a fully charged battery. If you need Web addresses or telephone numbers of charger manufacturers, please see the Chargers and Float Chargers and Battery Maintainers sections of Battery Information Links List. A cheap, unregulated "trickle" or a manual two-stage charger can overcharge a battery and destroy it by drying out the electrolyte.

A second method is to periodically recharge the battery when the State-of-Charge drops to 80% or below. Maintaining a high State-of-Charge tends to prevent irreversible permanent sulfation. The frequency of recharging depends on the parasitic load, temperature, battery's condition, and battery type. Lower temperatures slow down electrochemical reactions and higher temperatures will significantly increase them. A battery stored at 95° F (35° C) will self-discharge twice as fast than one stored at 77° F (25° C). Standard (Sb/Sb) batteries have a very high self-discharge rate; whereas, AGM (Ca/Ca) and Gel Cell (Ca/Ca) VRLA batteries have very low rates. Please see Section   7.1 for more information on battery types.

There are trade-offs between the economics of continuous "float" charging, where self-discharge and resulting sulfation does not occur, and periodic charging with the increased potential for a shorter battery life due to permanent sulfation. If you decide to

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periodically recharge the batteries while in storage, increasing recharge frequency, disconnecting any parasitic load, or storing them in colder temperatures will impede the self-discharge and reduce the possibility for permanent sulfation, but will also reduce the total number of life cycles.

A third technique is to use a solar panel or wind or water generator designed to "float" charge batteries. This is a popular solution when AC power is unavailable for charging. The size of a solar panel or wind or water generator required will depend on the average amount of available natural resource, battery capacity and temperature. Normally a five watt or larger panel is required for an average car battery. A charge controller (voltage regulator) is required when the peak current output exceeds 1.5% of the amp hour capacity of the battery.

A desulfator may be used in conjunction with any of the above methods.

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16.3. How do I recover sulfated batteries?

Here are some methods to try to recover permanently sulfated batteries:

16.3.1. Light Sulfation

Check the electrolyte levels and try one of the following three methods for removing light sulfation:

16.3.1.1. Equalize the battery. Please see Section   9.1.4. for more information on equalizing.

16.3.1.2. Apply a constant current at 2% of the battery's Reserve Capacity or 1% of the Amp Hour capacity rating for 48 to 120 hours, depending on the electrolyte temperature and capacity of the battery, at 14.4 VDC or more, depending on the battery type. Cycle (discharge to 50% and recharge) the battery a couple of times and test its capacity. You might have to increase the voltage in order to break down the hard lead sulfate crystals. If the battery gets above 125° F (51.7° C) then stop charging and allow the battery to cool before continuing.

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16.3.1.3. Use a desulfator, pulse charger or desulfating mode on a battery charger. A list of some desulfator or pulse charger manufacturers is available on the Battery References Links List at http://www.batteryfaq.org. Please note that despite desulfator manufacturers' claims, some battery experts feel that desulfators or pulse chargers do not work any better at removing permanent or preventing sulfation than do constant voltage chargers.

16.3.2. Heavy Sulfation

Check the electrolyte levels and try one of the following two methods for removing heavy sulfation:

16.3.2.1. Replace the old electrolyte with distilled, deionized or demineralized water, let stand for one hour, apply a constant current at four amps at 13.8 VDC until there is no additional rise in specific gravity, remove the electrolyte, wash the sediment out, replace with fresh electrolyte (battery acid), and recharge. If the specific gravity exceeds 1.300, then remove the new electrolyte, wash the sediment out, and start over from the beginning with distilled water. You might have to increase the voltage in order to break down the hard lead sulfate crystals. If the battery gets above 125° F (51.7° C) then stop charging and allow the battery to cool down before continuing. Cycle (discharge to 50% and recharge) the battery a couple of times and test capacity. The sulfate crystals are more soluble in water than in electrolyte. As these crystals are dissolved, the sulfate is converted back into sulfuric acid and the specific gravity rises. This procedure will only work with some batteries.

16.3.2.2. Use a desulfator, pulse charger or desulfating mode on a battery charger. A list of some desulfator or pulse charger manufacturers is available on the Battery References Links List at http://www.batteryfaq.org. Please note that despite desulfator manufacturers' claims, some battery experts feel that desulfators or pulse chargers do not work any better at removing permanent or preventing sulfation than do constant voltage chargers.

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16.4. Where Can I Find Additional Information On Sulfation?

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Please read Collyn Rivers' article, Battery Pulsing Devices. A circuit diagram of a desulfator can be found in this article by Alistair Couper Lead-Acid Battery Desulfator.

17. WHY WON'T MY ENGINE START?

Finding the reason why your engine will not start can be a very frustrating problem. The battery and starter motor's principal job is to start the engine. While the engine is running, the alternator, voltage regulator and battery all work together to provide stable source of power for your vehicle and to recharge the battery. All of these components, including the wiring and wiring connections, must be in good working order to start and operate your engine.

Assuming you have the battery's plates covered with electrolyte, sufficient fuel, the engine and ignition system are in good working order, and the electrolyte is not frozen, the following is a list of four simple instructions on how to troubleshoot the problem and isolate the source:

1. If there are no interior or exterior lights, intermittent or other strange electrical problems, CHECK the wiring, battery terminal mating surfaces, inside the positive top post or GM style side battery cable lug with multiple cables, and grounding strap between the engine and chassis for corrosion or oxidation. Clean each end to bare metal. Loose, bad or corroded connections are very common causes. If good, then

2. RECHARGE and TEST the battery for latent damage and TEST the charging system. If good, then

3. Test the starter. Burned solenoid contacts, worn starter motor brushes, loose starter motor bolts, or broken or corroded grounding straps are common problems for older vehicles.

4. If the problem continues or the battery drains overnight, TEST for excessive parasitic (ignition key off) drain.

Some auto parts or battery stores in the United States and Canada, like Auto Zone, Sears, Wal-Mart, Pep Boys, etc., will test your battery, charging system and starter for free. Simple stuff, like corrosion, bad or loose cable connections, loose alternator belt, loose starter bolts, or a dead battery, can cause your car not start. If the problem is not corrected, towing your vehicle to a good auto electric shop is highly recommended

18. WHERE CAN I FIND MORE INFORMATION ON BATTERIES?

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Additional information on car and deep cycle batteries maybe found on the Web site at http://www.batteryfaq.org/. For example, there is a frequently updated list containing hyperlinks to lead-acid battery manufacturer's sites, battery brand names, private labeling information and telephone numbers. There are two lists with hyperlinks to battery related product information and references about lead-acid batteries, for example, charging systems, regulators, isolators, test and monitoring systems, associations, books, magazines, history, directories, standards, etc. Also, there is a zipped (.zip) file of all documents and graphics contains of this Web site. It can found at Battery.zip.

Most of the battery manufacturers have a Battery FAQ posted on their web sites in addition to product information, specifications and charging voltages and procedures. Web addresses will often change, so you can use an Internet search tool like http://www.google.com/, http://www.yahoo.com/, etc. to locate the new addresses. These search tools are very effective in finding specific topics as well.

For questions, errors, omissions, comments, suggestions, broken link notifications or questions, please send e-mail to infoATbatteryfaqDOT.org. Please replace the AT with an @ and DOT with a period when typing the e-mail address. This is necessary due to the spam and viruses. I apologize for this inconvenience.

I highly recommend that you hyperlink to http://www.batteryfaq.org/ rather than republishing any of these documents because the information is frequently updated to keep up with advancements in batteries and changes in the battery industry, resources, hyperlinks, telephone numbers, etc. Major revisions will be indicated a higher version number and more recent date and minor changes with just a more recent date. These documents are in the public domain and can be freely reproduced or distributed without permission. Attribution is always appreciated, but not required.