Sealed Lead Acid Battery Questions

Also known as SLA, VRLA (valve-regulated lead-acid battery), sealed lead acid batteries have many uses in today’s world. From modern motorcycles, ATVs, home alarm systems, toys, backup systems, workout equipment, generators and the list goes on. These batteries come in all shapes, voltages, amperages and sizes. If you are unfamiliar with SLA batteries, this article will help with any questions you may have. Also, it is recommended to read if you are thinking about replacing your current sealed lead acid battery.

Do I Have to Use the Same Battery Manufacturer?

No, you may use other brands as long as the voltage and dimensions match your original battery. The difference in capacity (Ah) should not damage your unit. Check your system manual for minimum and maximum power requirements.

Can I Select an SLA With Different Capacity?

You may select a battery with a different capacity as long as it is within the same range. For example, if your current battery is 4Ah you may select a battery that is rated at 4.5Ah or 5Ah. Note; the battery size may change with a higher capacity. Always match your current voltage and dimensions to the replacement you select.

What is the Life of an SLA Battery?

The life of a sealed lead acid battery will depend upon a number of factors including application, operating temperature and the charging method. In general an SLA can last between 300-500 cycles. Never store the battery in a discharged or partially charged state. To extend the life of your battery, be sure to recharge your battery before storage.

What is the shelf life of my Sealed Lead Acid battery?

All SLA batteries self-discharge. If the battery is not recharged periodically, its full capacity may not be recoverable. Typically, SLA batteries self-discharge 3% every month. We recommend you check and recharge every three months. SLA batteries should never be stored longer than six months without being recharged. Store the battery in a dry, cool place. Ideal storage temperature is 65-70 degrees Fahrenheit.

Do I need to drain my Sealed Lead Acid battery to prevent memory effect?

No. SLA batteries do not suffer from memory effect. Draining your SLA battery may result in damaging it.

The Battery is Swollen, What Does That Mean?

Immediately remove the battery from the device. A battery becomes swollen as a result of overcharging. Excessive current will flow into the battery after the battery has reached a full charge. The constant current will cause decomposition of the water in the electrolyte and premature aging. At high rates of overcharge a battery will progressively heat up. As it gets hotter it will accept more current, heating up even further. This is called thermal runaway and it can destroy a battery in as little as a few hours. The heat will cause the battery to expand.

How to Connect a Battery in Series and Parallel?

You can connect your SLA battery in series or parallel. Connecting your SLA batteries in series will generate a higher voltage. For example, connecting two 12 Volt batteries will give you an output of 24 Volts.

Connecting your batteries in parallel will increase the capacity (Ah). For more information, please refer to ‘Connecting Your SLA Batteries Together’.

How Do I Charge the SLA Battery?

Some machines systematically charge the SLA battery, for example some home alarm or backup systems. Meaning, you do not have to take the battery out and charge it on a battery tender.

If you do need to charge your SLA battery with a battery tender, selecting the correct battery charger will impact the performance and service life of a sealed lead acid (SLA) battery. As a general rule of thumb when selecting a charger for an SLA battery is to use one that is no more than 20% of the capacity rating of the battery (at a 20hr. rate).

Example; to charge a 12 volt / 7.5Ah battery select a charger with a maximum charge output of 1.5 Amps (7.5 x 0.20 = 1.5).

What Terminal Do I Need?

Since SLA batteries are used in a variety of products, batteries are available in a variety of different terminal configurations. Please refer to our battery terminal page for pictures and dimensions of the different terminals.

I Dropped the SLA Battery, What do I do?

Please use protective gear before handling the battery to avoid exposure to sulfuric acid. Use rubber or neoprene gloves, safety glasses, acid resistant boots, apron and clothing. Neutralize any spilled electrolyte or exposed battery parts with soda ash or sodium bicarbonate until fizzing stops. Place the broken battery in a heavy gauge plastic bag or other non-metallic container. Recycle the battery immediately. Do not store old lead acid batteries, especially lead acid batteries with a broken case.

How Do I Recycle My SLA Battery?

Visit our Battery Recycling page for more information on how to properly dispose of your sealed lead acid battery.

SLA, VLRA, AGM, Is There a Difference?

SLA (Sealed Lead Acid) and VRLA (Valve Regulated Lead Acid) are different acronyms for the same battery. This battery type has the following characteristics: Maintenance-free, leak-proof, position insensitive. Batteries of this kind have a safety vent to release gas in case of excessive internal pressure build up. AGM (Absorbed Glass Mat) refers to a specific type of SLA/VRLA where the electrolyte is absorbed into separators between the plates consisting of sponge like fine glass fiber mats. SLA batteries are divided up into specific subsets of batteries.

AGM and Gel Cell Batteries Difference?

Both types of batteries are sealed, valve regulated batteries allowing them to be used in any position. The difference lies in the way the electrolyte is immobilized. In case of AGM (absorbed glass mat), the newer of the two technologies, the electrolyte is absorbed by the glass fiber separator who acts like a sponge. In a gel-type battery the liquid electrolyte turns into a gel right after the battery is filled. Gel batteries use a different type of separators which are not absorbent. Because of the design, gel cell batteries don't offer the same power capacity as do the same physical size AGM battery. For example, an AGM battery that is 12V 100AH, whereas, for example, a gel cell battery in the same size case would only be rated at 84AH.However, the Gel Cell excels in slow discharge rates and slightly higher operating temperatures. The internal design is otherwise similar.

GEL vs. (AGM) Sealed Lead Acid Batteries

AGM (absorbed glass mat) is a specially designed glass mat made to wick the battery electrolyte between the battery plates. AGM Batteries contain only enough liquid to keep the mat wet with the electrolyte and if the AGM battery is broken no free liquid is available to leak out. 

Gel Cell batteries contain a silica type gel in which the battery electrolyte is suspended. This thick paste-like material allows electrons to flow between plates but will not leak in a gel battery if the case is broken.

More often than not, AGM batteries are mistakenly identified as Gel Cell Batteries. Both batteries have similar traits such as being non-spillable, able to be mounted in any position, low self-discharge, safe for use in limited ventilation areas, and may be transported via air or ground safely without special handling.

AGM Batteries are preferred when a large amount of amps may be required. In most cases, recharge can be accomplished by using a good quality standard battery charger. The life expectancy (measured as cycle life or years) remains excellent in most AGM batteries if they are not discharged more than 60% between recharges and/or recharged fully every 3-6 months.

Gel Cell Batteries do not offer the same power capacity as do the same physical size AGM batteries. However, the Gel Cell excels in slow discharge rates and slightly higher operating temperatures and with excellent deep cycle capability. Gel Cell batteries are considered deep cycle batteries by virtue of their construction. One big issue with Gel Cell batteries that must be addressed is the CHARGE PROFILE. Gel Cell batteries must be recharged correctly or the battery will suffer premature failure. Please refer to the specification sheet for the max charging current limit. Using Gel Cell chargers is highly recommended.

Battery Disposal Guide

If you are having a difficult time finding out what to do with used batteries and where you can take them to be recycled or safely treated and disposed, then you should find a solution here on this page.

When it comes time to replace your batteries, make sure you are disposing of the old batteries properly so no laws are broken. Check with your local solid waste management district (listed under County Government in your phone book) for any outlets for household battery recycling. For disposal of small quantities of batteries, see if your local hardware/auto parts store or battery retailer will accept them for recycling. Most large battery recycling agencies and disposal companies are usually set up to serve industrial or municipal customers with bulk amounts of batteries rather than individuals.

Battery TypeCommon

NameSizes

Usage Examples

Disposal Classificatio

nProper Disposal

 Alkaline (maganese)

 Coppertop, Alkaline

 AAA, AA, C, D, 6V, 9V

 Flashlights, calculators, toys, clocks, smoke alarms, remote controls

 Non-Hazardous

 Trash (normal municipal waste). Exceptions: California, which requires non-households to dispose of these batteries in accordance with the California Universal Waste Rules. Also, Minnesota (Hennepin County only) requires these batteries be disposed as a hazardous waste

 Button

 Alkaline, Lithium, Mercuric Oxide, Silver Oxide, Zinc-Air

 Sizes vary

 Watches, hearing aids, toys, greeting cards, and remote controls

 Hazardous Waste

  Household Hazardous Waste Collection Site

 Carbon Zinc (non-Mercury)

 Classic, Heavy Duty, General Purpose, All Purpose, Power Cell

 AAA, AA, C, D, 6V, 9V

 Flashlights, calculators, toys, clocks, smoke alarms, remote controls, transistor radios, and garage door openers

 Non-hazardous

 Trash (normal municipal waste). Exceptions: California- requires non-households to dispose of these batteries in accordance with the California Universal Waste Rules. Minnesota (Hennepin County only)- requires these batteries be disposed as a hazardous waste

 Lithium Lithium, Lithium Ion, Li-Ion

 Sizes vary

 Laptops, cell phones, digital cameras, camcorders, mp3 players

 Hazardous Waste

  Recycle

 Nickel-Cadmium (Rechargeable

 Either unlabeled or labeled

 Sizes vary

 Camcorders, power tools, two-way

 Hazardous Waste

  Recycle or Household Hazardous Waste Collection Site

) Ni-Cdradios, cordless phones

 Nickel Metal Hydride (Rechargeable)

 Either unlabeled or labeled Ni-MH or Ni-Hydride

 Sizes Vary

 Camcorders, power tools, two-way radios, cordless phones, AA rechargeable batteries

 Non-hazardous waste

  Recycle or place in the trash (normal municipal waste). Exceptions: California- requires non-households to dispose of these batteries in accordance with the California Universal Waste Rules. Minnesota (Hennepin County only); requires these batteries be disposed as a hazardous waste

 Sealed Lead Acid

 SLA, AGM 2V, 6V, 12V

 UPS Back-Up systems, wheel chairs, ATV’s, Jet Skis

 Hazardous Waste

  Recycle

 Lead Acid (Wet cell)

 Automobile Battery

 6V, 12V

 Automobiles Hazardous Waste

  Recycle. Stores that sell car batteries are required to accept up to 5 car batteries from 1 customer for no charge.

 Mercury Oxide

 Mercury Oxide

 Mostly button. Sizes vary

 Watches, hearing aids, toys, greeting cards, remote controls

 Hazardous Waste

  Household Hazardous Waste Collection Site

 Silver Oxide Silver Oxide

 Mostly button. Sizes vary

 Watches, hearing aids, toys, greeting cards, remote controls

 Hazardous Waste

 Consumers are covered by the Household exemption under RCRA which allows for these batteries to be disposed of into the municipal waste stream. Non-Consumers must dispose of these batteries in full compliance with the hazardous waste rules. These batteries are also acceptable for recycling by the Rechargeable Battery Recycling Corporation's (RBRC) Battery Recycling Program

Battery Basics: A Layman's Guide to Batteries

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 basically 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. You can extend your battery life by hooking it up to a solar charger during the off months.

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)

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 basically 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 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 gel cell 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.

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. The standard rating is an Amp rating taken for 20 Hours. What this means, say for a 100 AH rated battery is this: Draw from the battery for 20 hours and it will provide a total of 100 amp-hours. That translates to about 5 amps an hour. 5 x 20 = 100. However, it's very important to know that the total time of discharge and load applied is not a linear relationship. As your load increases, your realized capacity decreases. This means if you discharged that same 100 AH battery by a 100 amp load, it will not give you one hour of runtime. On the contrary, the perceived capacity of the battery will be that of 64 Amp Hours.

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 silicone 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% 1.26512.7

6.3

75% 1.22512.4

6.2

50% 1.19012.2

6.1

25% 1.15512.0

6.0

Discharged 1.12011.9

6.0

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 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, 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 BATTERY 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.

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.

Battery Maintenance Facts

A battery is like a piggy bank, if you keep taking out, and putting nothing back, you soon will have nothing.

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.

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 stuck to the batteries positive plates and when you recharge the battery the sulfur returns to the electrolyte.

Safety

Remove all jewelry from hands; wear safety goggles and plastic gloves. Work away from open flames and no smoking, hydrogen gas that batteries make when charging is very explosive. Sulfuric Acid eats up cotton clothing, but does not affect polyester or wool. 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.

Battery Types, Deep Cycle and Starting

Basically there are two types of batteries, starting (cranking) and deep cycle (marine-golf cart-forklift). The starting battery is designed to deliver quick bursts of energy (such as starting engines) and have a greater plate count. The plates will also be thinner (more surface area) and have somewhat different material composition. The deep cycle

battery provides less instant energy but greater long-term energy delivery. Deep cycle batteries have thicker plate's design and can survive a greater number of deeper discharge cycles. Starting batteries should not be used for deep cycle applications. The so-called Dual Purpose Battery is only a compromise between the 2 types of batteries.

Wet Cell, Gel-Cell and Absorbed Glass Mat (AGM)

Wet Cell (flooded), Gel Cell and Absorbed Glass Mat (AGM) these are various versions of the lead acid battery. The wet cell comes in 2 ways, serviceable (removable vented caps) and maintenance free, both are filled with electrolyte and I prefer one that I can add water 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 well and do not tend to sulfate quite as fast as wet cell. Most Gel-Cell and some AGM batteries require special charging rate, especially the deep cycle models. I personally feel that careful consideration should be given to the AGM battery technology. Gel-Cell batteries still are being sold but the AGM batteries are replacing them in many cases. There is a little confusion about AGM batteries because different manufactures call them different names; a couple popular ones are regulated valve and dry cell batteries. In most cases AGM batteries will give a longer life span than a wet cell battery, but will not stand up as well to hot temperatures and high discharge load.

CCA, CA, AH and RC — What's That All About?

Well 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 good especially in cold weather. Cranking Amps (CA) measured at 32°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.

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.

Battery Maintenance

Battery Maintenance is an important issue. The battery should be clean. Cable connection needs to be clean and tightened. Many battery problems are caused by dirty and loose connections. Serviceable battery needs to have the fluid level checked regularly and only at a full charge. The fluid level will always be higher at a full charge. Distilled water is best; tap water is loaded with chemicals and minerals that are harmful to your battery, but not as bad as no water. Don't overfill battery cells especially in warmer weather. The natural fluid expansion in hot weather will 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 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.

Battery Testing

To measure specific gravity buy a temperature compensating hydrometer at an auto parts store. To measure voltage, use a digital D.C. Voltmeter.

You must first have the battery fully charged. The surface charge must be removed before testing. If the battery has been setting at least 6 hours you may begin testing. To remove surface charge the battery must experience a load of 20 amps for 3 plus minutes. Turning on the headlights (high beam) will do the trick. After turning off the lights you are ready to test the battery.

State of Charge Specific Gravity Voltage - 12V Voltage - 6V100% 1.265 12.7 6.375% 1.225 12.4 6.250% 1.190 12.2 6.125% 1.155 12.0 6.0

Discharged 1.120 11.90 6.0

* Sulfation of Batteries starts when specific gravity falls below 1.225 or voltage measures less than 12.4 (12v Battery) or 6.2 (6 volt battery). Sulfation hardens the 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 difference between cells in a strong healthy battery. 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, which indicates a shorted cell.

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

Selecting and Buying a New Battery

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 battery is not or can not receive regular maintenance, as it should. This is a hard call, because there is very little that substitutes for maintenance.

Be sure to purchase the correct type of battery for the job it must do. Remember an engine starting battery 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 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 Life and Performance

Battery life and performance, average battery life has become shorter as energy requirements increase. Two phrases heard 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) becomes so deeply discharged that they begin to coat the batteries lead plates. Before long the plates become so coated 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 storage, leaving a battery sit without some type of energy input.

Deep cycling engine start battery, remember these batteries can't stand deep discharge.

Undercharging of battery, to charge a battery let's say 90% of capacity will allow sulfation of battery using the 10% of battery chemistry not reactivated by the incomplete charging cycle.

Heat of 100+°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 damage than help.

Cold weather is 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.

Battery Charging

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 steps 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) decline 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 AGM batteries may require special settings or chargers.

Battery Do's

Think Safety First. 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.

Battery Don'ts

Don't add new electrolyte (acid). Don't use unregulated high output battery charger to charge batteries.

Don't disconnect battery cables while 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

General Difference Between Gel and Wet Batteries We are frequently asked "What are the differences between sealed or gel batteries and the more conventional wet, lead acid batteries.

Below are some general differences for the consumer to consider.

GEL WET

Requires stabilized, regulated charging system Conventional charging system OK

1.5 to 2.3 more expensive $ Less expensive $

Maintenance free, may operate in any positionRequires maintenance (water) upright operation only

May be shipped UPS FFA approved with restrictionsShipped common carrier only Cannot use for air travel

Float charging voltage 13.5 to 13.8 Float charging voltage 13.0 to 13.5

Cycle charging voltage 14.4 to 14.8 Cycle charging voltage 14.5 to 15.0

Does not deliver high CCA; better suited for long duration discharges

Delivers high CCA and can deliver long duration discharges

Lower capacities given dimensions Better capacities given dimensions

Slightly less AH per pound than wet Excellent AH per pound

Less ability to dissipate heat Excellent ability to dissipate heat

Less readily available for warranty More readily available for warranty

General Battery Care Procedures Never let the electrolyte level of a wet battery fall below the plates. Lack of maintaining the electrolyte in a

wet battery causes damage (sulfation) to the exposed portion of the plate which reduces capacity.

Never store a battery in a discharged state. The sulfate that forms during discharge should not be ignored for an extended time period because severe sulfation will take place sometimes, making the battery impossible to recharge fully. Sulfation starts at voltages less than 12.4(6.2) and at specific gravity less than 1.225.

Always fill your serviceable, wet batteries with water (preferably distilled)...after they have been charged (provided the plates are covered). If the electrolyte level is at least above the plates, do not fill the battery until after recharge. The electrolyte expands during charging and if you fill them before recharging, the electrolyte will possibly bubble out of the battery. The plates must be covered with electrolyte for recharge but be careful not to overfill.

Don't use battery strap that locks onto the battery posts for transporting battery. This type of device can physically damage the battery's internal connections.

Don't hammer battery cable clamps down on battery posts. This damages internal parts of the battery.

Don't add acid to a battery low on electrolyte solution. This increases the % acid above acceptable limits and causes pre-mature failure. Add only distilled water.

Don't use a fast charger that increases voltage across the battery terminals above 16 volts, especially when connected to the electrical system of the vehicle. A fast charger can damage sensitive electronic components.

Don't disconnect a battery cable while engine is running. This causes the charging voltage to rise since the voltage regulator loses its reference and cannot regulate the charging voltage. The higher voltage and voltage spikes can damage electronic components.

Always allow batteries to 'cool off' after charging. The cooling time is very important because heat is generated during the recharge and discharge cycles. Without the cooling time the heat grows, accelerating grid corrosion which is one of the major causes of battery failure.

Never charge a wet battery with a sealed (gel cell) battery charger. The wet battery needs the higher voltages to finish the charge and without it the batteries never come back to 100% and sulfation can occur.

Never charge a sealed (gel cell) battery with a wet battery charger. The higher voltages (above 14.8 volts) that a wet battery charger generates cause excessive gassing too fast for the sealed battery to recombine, causing dry-out and battery failure.

Always keep the tops and terminals of batteries clean and free of corrosion. The film on top of the battery can cause the current to migrate between the posts, accelerating self-discharge.

A fully charged battery will give you the best and longest service. Be sure the batteries are fully charged before testing or using in your vehicles. Even a perfectly new battery that is discharged only will fail load testing. Various states of charge of a battery, without a drain or load, after the surface charge has dissipated, are:

12.66 volts = 100% charged12.54 volts = 90% charged12.45 volts = 80% charged12.39 volts = 75% charged12.27 volts = 60 % charged12.18 volts = 50 % charged11.97 volts = 25 % charged11.76 volts = completely discharged

In situations where multiple batteries are connected in parallel, series or series1parallel, a replacement battery(s) should be of the same size, age and usage level as the companion.

As batteries age, their maintenance requirements change. Generally their specific gravity is higher. Gassing voltage goes up. This means longer charging time and/or higher finish rate (higher amperage at the end of charge). Usually, older batteries need to be watered more often. And, their capacity decreases.

Inactivity can be harmful to batteries. If they sit for several months, a 'boost' charge should be given; more frequently in warm climate (about once a month) than in cold (every 2-3 months). This is because batteries discharge faster at higher temperatures than at colder temperatures.

Monitoring either stabilized open circuit voltage or specific gravity will tell you when to charge and how much to charge batteries that are being stored. Battery voltage should not be allowed to drop below 12.4 for 12-volt batteries or 6.2 for 6-volt batteries. Specific gravity should not be allowed to drop below 1.225.

General deep cycle battery care procedures Cycle the battery lightly (20% or less depth of discharge) the first few cycles. This helps complete the

forming process of the plates (in case they are not completely finished forming). Always allow batteries to "cool off" after charging. The cooling time is very important because heat is

generated during the recharge and discharge cycles. Without the cooling time the heat grows, accelerating grid corrosion, which is one of the major causes of battery failure.

Opportunity charging (quick charging between uses) is detrimental to battery life. While it is true that the shallower the cycle, the more cycles the battery can deliver, opportunity charging is not good because the cooling time is eliminated, shortening life. (I.e. One charge cycle per day is preferable.)

Never charge a wet battery with a sealed (gel cell) battery charger.The wet battery needs the higher voltages to finish the charge and without it the batteries never come back to 100% and sulfation can occur.

Never charge a sealed (gel cell) battery with a wet battery charger. The higher voltages (above 14.8 volts) that a wet battery charger generates causes excessive gassing too fast for the sealed battery to recombine, causing dry-out and battery failure.

Never let the electrolyte level of a wet battery fall below the plates. Lack of maintaining the electrolyte in a wet battery causes damage (sulfation) to the exposed portion of the plate that reduces capacity.

Never store a battery in a discharged state. The sulfate that forms during discharge should not be ignored for an extended time period because severe sulfation will take place sometimes, making the battery impossible to recharge fully.

Always fill your serviceable, wet batteries with water (preferably distilled) after they have been charged). If the electrolyte level is at least above the plates, do not fill the battery until after recharge. The electrolyte expands during charging and if you fill them before recharging, the electrolyte will possibly bubble out of the battery. The plates must be covered with electrolyte for recharge but be careful not to overfill.

Always keep the tops and terminals of batteries clean and free of corrosion. The film on top of the battery can cause the current to migrate between the posts, accelerating self-discharge.

A fully charged battery will give you the best and longest service. Be sure the batteries are fully charged before testing or using your R..Vs. A fully charged battery, without a drain or load, after the surface charge has dissipated, is 12.63 volts for a 12 volt battery. Other states of charge are: 12.60 volts = 93% charged 12.55 volts = 89% charged 12.50 volts = 85% charged 12.45 volts = 80 % charged 12.18 volts = 50 % charged.

An overly discharged battery may need to be cycled a few times before it can recover fully. If a battery begins to heat before coming up to a full state of charge, it may be necessary to discharge the battery and recharge it a few times. This charge and discharge cycle may help the current acceptance of the battery and facilitate its recovery to a usable condition.

In situations where multiple batteries are connected in parallel, series or series/parallel, a replacement battery(s) should be of the same size, age and usage level as the companion batteries. Do not put a new battery in a pack that has 50 or more cycles. Either replace with all new or use a good used battery(s).

Deepcycle batteries need to be equalized periodically. Equalizing is an extended, low current charge performed after the normal charge cycle. It helps keeps cells in balance. Actively used batteries should be equalized once per week. Manually timed chargers should have the charge time extended about 3 hours. Automatically controlled chargers should be unplugged and reconnected after completing a charge cycle.

As batteries age, their maintenance requirements change. Generally their specific gravity is higher. Gassing voltage goes up. This means longer charging time and/or higher finish rate (higher amperage at the end of charge). Usually, older batteries need to be watered more often. And, their capacity decreases.

Inactivity can be harmful to deep cycle batteries. If they sit for several months, a "boost" charge should be given; more frequently in warm climate (about once a month) than in cold (every 2-3 months). This is because batteries discharge faster at higher temperatures than at colder temperatures.

Reasons Why Batteries Fail

Physical Condition: Sediment accumulates under the plates and can short out a cell. Plate separators fail to insulate the positive and negative plates in a cell and the cell becomes shorted, ruining the battery.

Insufficient Electrolyte: Allows top exposed portion of plates to sulfate rapidly. This reduces the battery's ability to accept recharge. Accelerated erosion of lower portions of plates in a higher than normal acid content electrolyte may also occur when the electrolyte solution is low. The battery also has a higher internal resistance when low on water. High resistance means heat which mean shorter battery life.

Sulfation: When a battery is allowed to remain discharged too long the accumulated lead sulfate on the plates hardens. The sulfate from the plate is not able to reconstitute the electrolyte to the higher specific gravity, or to restore the plate material to a more active composition.

Overheating: A battery operated when the electrolyte temperature reaches 125 F, increases chemical action. This increases corrosion of the plates and reduces battery life. When overheated, the battery plates tend to buckle and destroy the structural integrity of the battery.

Freezing: When the electrolyte freezes, the ice formed will dislodge active material from the plates. Battery case may crack and electrolyte will leak out when thawed.

Corrosion: Corrosion from spilled or splashed electrolyte forms deposits that can conduct electricity and cause battery drain. Clean off all corrosion. Prevent its accumulation by coating terminals and exposed metal cable connectors with high temperature grease.

Vibration: Vibration from an improperly installed battery shakes off active material from the positive plate and reduces battery life. When installing a battery, always insure the battery is securely fastened down.

Overcharging: Overcharging rapidly converts water to gas and decreases the electrolyte water content. The electrolyte level drops, and becomes more acid in content. This subjects the plates to a higher concentration of acid and results in some plate area not being covered with electrolyte. Prolonged overcharging generates excessive heat inside the battery which buckles the plates and destroys the battery. About 58% of battery failures are caused by overcharging.

State of Charge and Sulfation

To ensure proper testing of batteries and to avoid premature battery replacement, the consumer should be aware of some critical information based upon the "state of charge". Nationally, between 30% to 50% of all batteries picked up as "junk" batteries are actually good, useable batteries (taken from Battery Council International source). There are many reasons for this alarming statistic but as a consumer, if you know some "rules" about battery testing and battery state of charge, you’ll be informed and will avoid the pitfalls that many fall unto.

Below is a very important table which compares battery "state of charge", "specific gravity" and "voltage". The line passing through the "75%", "1.225", and "12.40" represents important information for the consumer. If your battery has a measured specific gravity of less than 1.225 and a voltage less than 12.4, it usually will fail the prescribed "load test" that battery specialists use as their most important diagnostic test. As a consumer, if the battery does not have a "dead cell", you should insist that it be charged to a level above 1.225 specific gravity (where it can be measured) and then tested before purchasing a new battery. We recommend that you focus on specific gravity (for serviceable batteries) as this measurement provides a more accurate reading of state of charge than open circuit voltage. Accurate voltage readings require that the battery sit up to 2 hours before measurements can be made. Why buy a new battery just to simply replace a discharged one?

For those of you who store your batteries or let them sit without use, be aware that a process called "sulfation" occurs if the battery’s specific gravity falls below 1.225 or below 12.4 volts. Sulfation is actually a hardening of the battery’s internal plates which need to remain soft and porous so that acid can flow through them. If the flow of acid is reduced, the battery performance is greatly reduced regardless of how much you attempt to charge the battery. Monitoring your batteries for these parameters, particularly specific gravity as it changes less rapidly than voltage, will ensure you get maximum life from them.

STATE OF CHARGE

VS

SPECIFIC GRAVITY

VS

VOLTAGE

100%   1.265  12.62(6.3

)

90%   1.251   12.54

80%   1.236   12.45

75%   1.225  12.40(6.2

)

60%   1.206   12.27

50%   1.190   12.18

25%   1.155  11.97(6.0

)

DISCHARGED   1.120   11.76

Connect Your Batteries for Optimum Efficiency

When batteries are connected in parallel, as in most R.V’s, the positive terminals are connected together and the negative terminals are connected together as shown below:

The main advantage of these parallel connections is that the total current delivering capacity is the sum of each battery’s current. The total current is equal to the sum of both batteries. The main disadvantage of this type of connection is that the total voltage available cannot exceed the voltage of the weakest battery.

Unfortunately, too often we see parallel connections that may be less efficient. For example, the diagram below shows the traditional way to connect the cables to a dual-battery pack.

The positive and negative cables are connected to the terminals on the same battery, battery #1. This puts more of the load on battery #1 for the cranking mode and it also gets a higher charging voltage when the dual-battery pack is being charged. Battery #2 doesn’t work as hard because it has extra resistance to overcome in the cables that connect it to Batt #1. Battery #1 doesn’t see that resistance so it is not affected. The cable and connection resistances reduce the efficiency of battery #2 when cranking or charging especially if corrosion develops. The figures shown below demonstrate more efficient ways to connect the battery cables to a dual and triple-battery pack.

Just A Little Corrosion Causes Big Voltage Drops

When one amp of current passes through a circuit with zero ohms (the unit of measure for resistance) of resistance, no voltage drop occurs. Even when the circuit current increases to 200 amps through zero ohms, still no voltage drop occurs. The amount of resistance encountered by a current causes a voltage drop. Ohm's Law explains how small resistance values can cause severe voltage drops. The basic form of Ohm's Law is E = I x R, where the current, I in amps, is multiplied by the resistance, R in ohms, to equal the voltage drop, E in volts. To see the affect resistance has on voltage we use Ohm's Law and solve for voltage as shown here by the following equation: I(Amps) X R(Ohms) = E(Voltage).

By substituting different values for resistance, we can see small resistances can cause significant voltage drop problems, especially in high amperage systems as shown below:

1 Amp X 0(Ohms) =0 (no voltage drop)

200 Amp X 0(Ohms)

=0 (no voltage drop)

1 Amp X 1 Ohm = 1.0 volt dropped

200 Amp X 0.01 Ohm

= 2.0 volt dropped

200 Amp X 0.02 Ohm

= 4.0 volt dropped

The Society of Automotive Engineers, S.A.E., has established the maximum voltage drops for common electrical circuit cables and connections. The acceptable voltage drops are shown below:

Voltage Drop (Volts)

American Wire Size

Current

Component Application

0.01-.09 16 - 20 1-20Computer Connections, Low Current

Accessories

0.1-.2 4 - 14 20-100 Alternators, High Current Accessories

0.2 00 - 4 100+ Battery/Starter Cables

0.2-.3 N/A 100+ Heavy Duty Switches, Solenoids

Don't Be Misled By Battery Ratings

For years “Cold Cranking Amps (CCA tested at 0 F) have been the industry standard of battery amp rating, but in recent years some battery marketers began testing their products at different temperatures, which result in different ratings.  “Cranking amps”(CA), sometimes called “Marine Cranking Amps”(MCA), for example, test battery performance at 32 F or 0 C, so the rating numbers will be higher than a CCA rating.  Since manufacturers’ specifications are based on 0 F, you may want to base your buying decision on the CCA rating.

That’s why it is important to remember, batteries displaying higher rating numbers don’t necessarily deliver more performance.  Check your battery catalog/replacement guide or your auto’s owner manual to make sure you are buying a product that meets your vehicle’s requirements-and be sure to take a good look at the temperature at which a battery has been tested and the reserve capacity.  If you don’t examine the battery label closely, you could end up with a product that is not really powerful enough to serve your vehicle.  With today’s electronically-sophisticated equipment, your vehicle depends on your battery more than ever.

You also may see a battery rated with “Hot Cranking Amps”(HCA) or some other unfamiliar rating.  Most products marketed with an HCA rating promise better performance in warm climates, but beware! Only CCA and CA ratings are approved by the Battery Council

International(BCI).  In fact, the BCI requires that “CA”-rated products carry a “CCA” rating with equal prominence so that proper comparisons can be made. You can’t really be sure of a rating that is not approved by the BCI.

Presented below is a table which shows the differences between CCA’s, CA’s and HCA’s.

CCA’s CA’s HCA’s

     

0 F 32 F 80 F

     

275 340 400

345 430 500

415 520 550

450 560 650

520 650 750

590 740 850

625 780 900

660 825 950

695 870 1000

765 960 1100

To avoid the trap of such marketing gimmicks, you can calculate the approximate CCA from other ratings by the following formulas:

CA (@32  ) X .80 = CCA  and  HCA (@80) X 0.60 = CCA

Which Deep Cycle Battery Do I Choose?

Below is a table showing the specifications of popular Centennial and Batteries Northwest wet-lead acid, deep cycle batteries and some Trojan group sizes also. Measurements are “overall dimensions” and therefore include any handles, ridges, etc.

GROUP SIZE CCA(0 deg) RES. CAP / WEIGHT 20 HR. CAPACITY

DIMENSIONS

Length

Width Height

DP24(CEN) 550 125/41 85 11 1/4 6 3/4 9 3/4

DC24(CEN) 600 150/46 87 11 1/4 6 3/4 9 3/4

DC2 (CEN) 650 160/52 105 12 3/4 6 3/4 9 3/4

DC31MF(CEN) 800  225/61 135 13 1/4 6 13/16 9 1/4

B2200 (BatNW)* 500 220/63 225 10 3/8 7 1/811

3/16

B24DC(BatNW) 600 110/41 80 11 1/4 6 3 /4  9 3/4

B27DC(BatNW)  650 145/52  87 12 3/4 6 3/4 9 3/4

SCS150(Trogan) ----- 150/50 100 11 1/4 6 3/4 9 3/4

SCS200(Trojan) ----- 200/60 115 12 3/4 6 3/4 9 3/4

SCS225(Trojan) ----- 225/66 130 14 6 3/4 9 3/4

T-105(Trojan)* ----- 447/62 225 10 3/8

7 1/8 10 7/8

T-125(Trojan)* ----- 488/66 235 10 3/8 7 1/8  10 7/8

T-145(Trojan)* -----  530/72   260 10 3/8 7 1/8  11 5/8

*Please note that these are 6 Volt batteries and two of them, connected in series, are required to produce 12 volts.

The deep cycle batteries shown above have plate designs that consist of a higher density active material than standard automotive batteries.  This higher density material enables the plates to withstand the stresses of repetitive cycling better. 

The grid alloy in a deep cycle is specially formulated to increase the active material adhesion to the grid thereby providing additional protection against the stresses and abuses of cycling and vibration.

One significant advantage of using the grid alloy (antimony) in deep cycle batteries is that it allows the user to cycle(discharge and recharge) the battery over 250 to 2200 cycles, depending on the type and depth of cycle.   One disadvantage is that while “extra” cycling is enhanced, this battery gasses more and water levels must be checked routinely. The atimoney alloy also increases the “self-discharge rate” when compared to automotive, absorbed glass mat (AGM) or gel batteries.

The Plates designed for GC2200, T-105 , T-125 and T-145 use the same active material and alloy of the other deep cycle batteries but both negative and positive plates are up to 60% thicker than those found in a 24DC or 27DC. The significance of this is that these 6 Volt batteries should have life span up to 60 to 70% longer than the other batteries listed.

Daily Amphere-Hour Consumption For Your RV

Those RV-ers who prefer to stay in campgrounds with full hookups have different requirements than those who enjoy primitive camping without hookups. 

If you never boondock and always stay in places with electrical hookups, you probably can get by with one good quality deep-cycle battery.  However, those RV-ers who sometimes or regularly depend on battery power for the house systems need to do some calculating in order to have enough batteries of the proper size to meet their requirements.

The first step is to figure a typical day’s ampere-hour consumption.  It is easy to do:  Simply multiply the amperage draw of each item of equipment in the RV by the number of hours it will be used each day.  Amperage draw is found on equipment labels, stamped into the casings, or in the instruction booklets.  If your RV manual list only lists watts, watts can be converted to amperage by dividing by voltage (12 volts).  Amperage draws can be directly measured also with an appropriate “amp meter”. Typical amperage draws of common RV equipment are listed in the table* below:

Three lights for 4 hours(4 hrs. x 4.5 amps) =18.00

Ah

Water pump for 45 minutes; includes two showers (.75 hrs. x 5 amps) =

3.75 Ah

TV, color for 2 hours(2 hrs. x 4 amps) = 8.00 Ah

Miscellaneous (clock, LED pilot lights, etc) 2.00 Ah

Total31.75

Ah

The total daily consumption of 31.75 may not seem like much, but, in relation to battery capacity, it can be considerable.  If the RV has only one Group 24 battery with a rating of 90 Ah, using 31.75 Ah would deplete 32% of the battery’s capacity.  Two Group 24’s connected in parallel have the capacity of 180 Ah (90 Ah + 90 Ah).  A daily consumption of 31.75 Ah would deplete 17% of the capacity available.  If you dry camped for 3 day (31.75 x 3 days= 95.25 Ah), 52% of your battery capacity would be depleted.  The more Ah capacity that is available to your DC accessories, the longer your systems will run.  You can increase more Ah by using either higher capacity batteries or connecting multiple batteries (2 or 3 or 4) in parallel, if you have room in the battery tray.

* This information is taken from “RV ELECTRICAL SYSTEMS-A Basic Guide to Troubleshooting, Repair and Improvement” by Bill and Jan Moeller, 1994, Ragged Mountain Press, Camden, Maine.

Safety Tips on Charging Batteries

Specific charging rates or times cannot be specified for batteries due to several factors that can vary, such electrical capacity of battery, temperature of electrolyte, state of charge and battery age and condition. We recommend the use of a hydrometer which measures specific gravity to monitor "how much" to charge.

These following tips can be used as a general guide for safe charging.

1. Charge batteries in well ventilated area. Don't smoke around charging batteries, they can explode.

2. Wear protective goggles and clothing. The National Society to Prevent Blindness reports, for instance, that in 1984, 14,238 people suffered serious eye damage mishandling batteries. Most were "Do it Yourself-ers".

3. Always assume that explosive mixtures of hydrogen and oxygen gases are present near the battery at all times.

4. Don't remove caps when charging a battery. Most vent caps are now designed to be flame resistant.

5. Cover the vent cap area of battery with a wet cloth to inhibit sparks from igniting escaping gas.

6. Connect charger to battery terminals while charger is turned off. The turn on the charger. This reduces the chance of sparks being generated.

7. Charge single batteries at a specific rate for a specific time determined by the battery's Reserve Capacity Rating:

Reserve Capacity

Slow Charge Fast Charge

80 minutes10 hrs at 5

amps2.5 hrs at 20

amps

80-125 15 hrs at 5 4.0 hrs at 20

minutes amps amps

125-170 minutes

20 hrs at 5 amps

5.0 hrs at 20 amps

8.

9. (If batteries are connected in parallel for charging, the output of the charger will be divided equally among the number of batteries being charged and the charging time will increase).

10. Recharging at the slower rate will prolong battery life.

11. If a battery fails to test "good" after two charging and load test cycles, replace the battery.

Determining When A Battery is Fully Charged 1. The best way to determine when a battery is fully charged is to check specific gravity of each cell with a

hydrometer. (background--As the battery discharges, the sulfuric acid content of the electrolyte solution is reduced, leaving water. Therefore, the specific gravity decreases as the battery is discharged).

2. Specific gravity measurements show the state of charge of a battery according to the following chart.

State of Charge

Specific Gravity

100% 1.26575% 1.22550% 1.19025% 1.155

Discharged 1.1203.

When a battery is below 75% of full charge, sulfation (or hardening) of the plates begins to occur and permanent battery damage may result. It is important to keep batteries as fully charged as possible.

POINTS TO REMEMBER WHEN USING A HYDROMETER

1. Hold the hydrometer vertically so the float is free and does not touch the inner walls of the barrel.2. To increase accuracy of the hydrometer, draw electrolyte into the bulb a few times until the hydrometer

parts reach the same temperature as the electrolyte.

3. Hold the hydrometer so that liquid is level in barrel and at eye level.

4. Read specific gravity from the scale on the calibrated float at the point where the surface of the liquid crosses the float.

5. Check each individual battery cell. Specific gravity should not vary more than .050 or "50", points between cells. If a cell varies more than 50 points, charge again. If this difference still remains, replace the battery.

6. Measure the electrolyte temperature with a thermometer for best accuracy. Then correct hydrometer readings for electrolyte temperature (see hydrometer instructions for details on temperature compensation ... normally, in the summer this does not have to be done given our climate in the Northwest).

Why Are My Batteries Discharged It is frustrating to find our batteries discharged, particularly in the spring after our boats, R.V.'s,

motorcycles, personal watercrafts, etc. have been in storage for the fall and winter. With a little maintenance and information, you can avoid the frustrations of "discharged batteries" and the

cost of buying new batteries as well.

Did you know that a battery starts to discharge once it is filled with electrolyte. Here in the Northwest, most boat and car batteries left unattended (and assuming no "parasitic drains" from computers, etc) will not start the engine after about 3 months. For smaller batteries such as personal watercraft and motorcycles, it takes only about a month to discharge the battery to 75%, which usually will prevent the engine from starting. In hotter climates, this can occur in less time than those specified above.

Discharged batteries not only won't start your vehicle but will become ruined and in need of replacement if left without any maintenance. A process called "sulfation" occurs if the battery voltage drops below 12.4

volts or if specific gravity drops below 1.225 as measured by hydrometer. Sulfation actually hardens the battery's internal plates, which need to remain soft and porous so that the electrolyte can flow through them.

Monitoring your batteries for these parameters, voltage and specific gravity, can be done easily and cheaply and will ensure maximum life from your batteries. All you need is a voltmeter and hydrometer.

Armed with this information you can then determine if you need to charge your battery.

For those applications where batteries are stored for over 2-3 months "without use", an excellent option to maintain your batteries are the "completely automatic, complete shut off "chargers that are now available. These chargers have computer chips that sense when the battery needs charging and automatically turns itself on. After the battery is charge it automatically turns itself off and therefore never overcharges or undercharges your batteries. They can be left connected to an AC outlet indefinitely. Contact us for more information.

What is the difference between series battery connections and parallel battery connections and how do they increase battery capacity and voltage?

Answer: In the SERIES CONNECTION, batteries of like voltage and Amp-Hr capacity are connected to increase the Voltage of the battery bank. The positive terminal of the first battery is connected to the negative terminal of the second battery and so on, until the desired voltage is reached. The final Voltage is the sum of all the battery voltages added together while the final Amp-Hr, Cranking Performance and Reserve Capacity remain unchanged.

Battery System: 12 Volt, 225 AH Using Two T-105 Deep Cycle Batteries 

(6 Volts, 225 AH each)

Answer: In PARALLEL CONNECTION, batteries of like voltages and capacities are connected to increase the capacity of the battery bank. The positive terminals of all batteries are connected together, or to a common conductor, and all negative terminals are connected in the same manner. The final voltage remains unchanged while the capacity of the bank is the sum of the capacities of the individual batteries of this connection. Amp-Hrs, Cranking Performance and Reserve Capacity increases while Voltage does not.

Battery System: 6 Volt, 450 AH Using Two T-105 Deep Cycle Batteries 

(6 Volts, 225 AH each)

DEFINITIONS

COLD CRANKING AMPS (CCA):  The maximum amperes that can be continuously removed from a battery for 30 seconds at zero degrees F before the voltage drops too low to use (7.2 volts).  This term is used only for engine starting batteries, and has little to do with the amp-hour capacity or deep cycle batteries.  This rating will also appear on many deep cycle marine batteries.

CRANKING AMPS (CA):  A rather optimistic market driven rating, especially for “economy” or “value priced” batteries.  The same CCA, but a 32 degrees F (0 C) temperature.  The standard Battery Council International rating is CCA, at 0 degrees F (about -18 C).  The MCA, or Marine Cranking Amps is basically the same at CA.  CCA is about 20% less than CA or MCA.

RESERVE CAPACITY (RC): Reserve capacity is sometime used to rate deep cycle batteries.  It is the number of minutes that a battery can maintain a useful voltage at a constant 25 amp discharge rate at 80 degrees that run heavy loads, although most batteries also have tables that show the AH capacity at different discharge rates.  AH is approximately equal to RC X 0.60)

Jump start procedures 1. Before attempting to jump start the car, it is important to use safety glasses. Measure battery

terminal post voltage with a volt meter to determine if battery has a shorted cell. A car should not be jump

started if the battery has a shorted cell. The voltage at the shorted battery remains about two volts low even with the jumper cables connected. Attempts to jump start the car could result in damaged computer memories or alternator damage from voltage spikes from the source battery. Using jumper cables and jump starting should be the last resort.

Background:  A reading of 11.89 volts(0% charge) indicates the battery state of charge and a shorted cell may not exist in the battery. Compare the actual reading obtained to the BATTERY VOLTAGE vs. STATE OF CHARGE CHART to determine the battery’s state of charge shown below. Readings below 12.45 volts indicate low state of charge and might be the reason the battery cannot crank the engine. A reading of about 10.55 volts(4.22 for six volt batteries), indicates the battery may have a shorted cell and should be replaced.

OPEN CIRCUIT VOLTAGE

vs.STATE OF CHARGE

     

12.66 VOLTS   100% CHARGED

12.45   75

12.18   50

11.97   25

11.76   0

2. Place the source car (good battery) close enough to the dead car so that jumper cables can reach between the batteries without stretching too tight.  The jumper cables should be long enough and the cars close enough so the jumper cables have plenty of slack.  Do not let car bumpers touch each other. Wear protective eye glasses. Do not attempt to jump start a car if gasoline fumes are present around either the source car or the car with the dead battery.

3. Turn the source car off before making any jumper cable connections between the two batteries. Having the source car OFF lowers the voltage on the source battery voltage. The lower voltage helps reduce the amplitude of voltage spikes generated when jumper cables are connected to the dead battery. Make your last connection be the ground on the car being jumped and maximize the distance of this connection from the positive terminal.

Background:  Avoid voltage spikes at the battery terminals. Voltage spikes are generated when jumper cables or battery charger cables are connected to the battery terminals of a weak or dead battery.  These voltage spikes can shock computers memories and alter information stored in sensitive memory chips inside computers.  The most sensitive memory chips are called EEPROMs (Electrically-Erasable PROMs) or NVM chips (Non-Volatile Memory).

Preparing your batteries for winter

Winter is the hardest on your car.  Colder temperatures make your engine harder to crank and your battery less able to crank the engine over. There are services that should be performed now to

maintain vehicle reliability.  If you believe out-of-sight, out-of-mind is acceptable for vehicle maintenance, it’s time for a reality check.  Good vehicle performance is directly linked to the care it

receives.

1. Visually inspect your battery for clean surfaces, loose connections, and corrosion. Dirt, corrosion and moisture provide a path for energy to escape from the battery. When corrosion      or dirt accumulates, use a weak solution of baking soda and water to clean the battery’s exterior. You may need a wire brush to scrub the terminals.  Loose connections also may result in an explosion!  Battery cables are important as defective cables and poor connections are two of the top reasons for cranking problems.  Keep cable and connections “bright and tight”.  Play close attention to ground connections.

2. Make sure you maintain the electrolyte levels (for serviceable batteries) between above the battery’s plates and below the vent well cap opening. Plates exposed to air will sulfate, become hard and brittle and you’ll loose battery power. Be careful not to overfill.  Adding too much water not only dilutes the electrolytes sulfuric acid but can cause a drop in voltage.  Never add acid to the battery!

3. Measure the “state of charge” with preferable a hydrometer.  If the battery is sealed, let the voltage equilibrate and determine “state of charge” with an accurate volt meter.  Appropriate charge levels (1.265 specific gravity as measured by a hydrometer and 12.6 volts as measured with a volt

meter) are very important component of year around maintenance.  A discharged battery will lead to a starting failure.  A battery stored in a discharged state is susceptible to sulfation and freezing.

4. Have your battery tested by a mechanic or battery specialist to ensure that it meets manufacturing specs for its power.  Not all batteries are created equal. You need a load tester or other digital battery testing equipment to accurately test the battery.  If the battery does not met manufacturer’s specs, then replace the battery with one that does.

5. If you are storing batteries be sure to charge the battery before storage and store them in a cool, dry location.  Once a battery is filled with electrolyte, it discharges at 1% a day at 70 degree Fahrenheit. Cooler temperatures, from 40 to 60 degrees F are ideal. Discharged batteries can freeze at 18 degrees F.  Batteries stored in cars newer than 1981 have parasitic drains that will further discharge the batteries.  Check with a specialist before disconnecting the battery from the car’s electrical system.  Charge automotive, R.V. batteries every 3 months.  Charge motorcycle and ATV batteries once every month.  For vehicles left in storage including cars, R.V’s,  trucks, motorcycles, personal water craft, etc, there are several very good manufacturers (i.e. Interactor, VDC Electronics, Battery Tender, etc) that have perfected “completely automatic” chargers that will maintain your batteries at a “full state of charge” but not overcharge.

Advantages and Disadvantages of using two 12 volt batteries connected in parallel or two 6 volt batteries connected in series.

It would appear that there is no significant difference in capacity and voltage between these two examples. But this really is not the case. The plates designed for the T-105 use the same active material and alloy of the group 27 deep cycle batteries but both the T-105 negative and positive plates are 60% thicker than those found in the deep cycle 27 group sizes. The significance of this is that these 6 Volt batteries should have a longer lifespan than the two deep cycle 27 group sizes, if properly cared for. While the capacities are similar (220 versus 225 Amp Hrs.), battery longevity favors the two 6 Volt batteries. Why? Because a major cause of deep cycle battery failure is the shedding of active material from the battery plates.

Testing the battery

Presented below are the “basic” testing procedures used by professionals to determine if your battery is “good” or “bad”.  These are presented in a “bullet format” for ease of reading and interpreting.  More detailed discussion can be found on the internet should you want to pursue it.

STEP 1:  VISUAL INSPECTION

Check the battery case for breaks and leaks

Clean corrosion off battery and terminals if present

Check to see if electrolyte levels (if low maintenance battery) are above plates

Check electrolyte color (if low maintenance battery) A dark color indicates overcharging)

If the battery is sealed, check for cracks or corrosion

STEP 2:  STATE OF CHARGE

Check with hydrometer (if low maintenance battery)

If readings are less than 50 specific gravity points between highest and lowest cell, go to step 3; if not, continue

Recharge if one or more cells are below 1.225 specific gravity

Remove surface charge with a load tester if battery has been on charge

If the battery is sealed, determine “state of charge” with an accurate volt meter

If voltage for sealed battery is below 12.6 charge the battery with automatic charger and then proceed to step 3.

STEP 3:  LOAD TEST THE BATTERY

Apply ½ the CCA rating for 15 seconds and compare resulting voltage with voltage chart

At 70 degrees the voltage should remain above 9.6 volts to pass; at 60 degrees passing voltage is 9.5; at 50 degrees passing voltage is 9.4; at 30 degrees passing voltage is 9.1 volts.

STEP 4:  ANALYZE RESULTS

Continue to observe bounce back voltage after load is removed.

If battery voltage fails to bounce back to 12.4 volts for 12-volt batteries and 6.2 volts for 6-volt batteries, recharge and recheck.

Can the Lead-acid Battery Compete in Modern Times?

The answer is YES. Lead-acid is the oldest rechargeable battery in existence. Invented by the French physician Gaston Planté in 1859, lead-acid was the first rechargeable battery for commercial use. 150 years later, we still have no cost-effective alternatives for cars, wheelchairs, scooters, golf carts and UPS systems. The lead-acid battery has retained a market share in applications where newer battery chemistries would either be too expensive.Lead-acid does not lend itself to fast charging. Typical charge time is 8 to 16 hours. A periodic fully saturated charge is essential to prevent sulfation and the battery must always be stored in a charged state. Leaving the battery in a discharged condition causes sulfation and a recharge may not be possible.

Finding the ideal charge voltage limit is critical. A high voltage (above 2.40V/cell) produces good battery performance but shortens the service life due to grid corrosion on the positive plate. A low voltage limit is subject to sulfation on the negative plate. Leaving the battery on float charge for a prolonged time does not cause damage.

Lead-acid does not like deep cycling. A full discharge causes extra strain and each cycle robs the battery of some service life. This wear-down characteristic also applies to other battery chemistries in varying degrees. To prevent the battery from being stressed through repetitive deep discharge, a larger battery is recommended. Lead-acid is inexpensive but the operational costs can be higher than a nickel-based system if repetitive full cycles are required.

Depending on the depth of discharge and operating temperature, the sealed lead-acid provides 200 to 300 discharge/charge cycles. The primary reason for its relatively short cycle life is grid corrosion of the positive electrode, depletion of the active material and expansion of the positive plates. These changes are most prevalent at higher operating temperatures. Cycling does not prevent or reverse the trend.

The lead-acid battery has one of the lowest energy densities, making it unsuitable for portable devices. In addition, the performance at low temperatures is marginal. The self-discharge is about 40% per year, one of the best on rechargeable batteries. In comparison, nickel-cadmium self-discharges this amount in three months. The high lead content makes the lead-acid environmentally unfriendly.

Plate thickness

The service life of a lead-acid battery can, in part, be measured by the thickness of the positive plates. The thicker the plates, the longer the life will be. During charging and discharging, the lead on the plates gets gradually eaten away and the sediment falls to the bottom. The weight of a battery is a good indication of the lead content and the life expectancy. 

The plates of automotive starter batteries are about 0.040" (1mm) thick, while the typical golf cart battery will have plates that are between 0.07-0.11" (1.8- 2.8mm) thick. Forklift batteries may have plates that exceed 0.250" (6mm). Most industrial flooded deep-cycle batteries use lead-antimony plates. This improves the plate life but increases gassing and water loss.

Sealed lead-acid

During the mid 1970s, researchers developed a maintenance-free lead-acid battery that can operate in any position. The liquid electrolyte is gelled into moistened separators and the enclosure is sealed. Safety valves allow

venting during charge, discharge and atmospheric pressure changes.

Driven by different market needs, two lead-acid systems emerged: The small sealed lead-acid (SLA), also known under the brand name of Gelcell, and the larger Valve-regulated-lead-acid (VRLA). Both batteries are similar. Engineers may argue that the word 'sealed lead-acid' is a misnomer because no rechargeable battery can be totally sealed. 

Unlike the flooded lead-acid battery, both SLA and VRLA are designed with a low over-voltage potential to prohibit the battery from reaching its gas-generating potential during charge because excess charging would cause gassing and water depletion. Consequently, these batteries can never be charged to their full potential. To reduce dry-out, sealed lead-acid batteries use lead-calcium instead of the lead-antimony.

The optimum operating temperature for the lead-acid battery is 25*C (77*F). Elevated temperature reduces longevity. As a guideline, every 8°C (15°F) rise in temperature cuts the battery life in half. A VRLA, which would last for 10 years at 25°C (77°F), would only be good for 5 years if operated at 33°C (92°F). The same battery would desist after 2½ years if kept at a constant desert temperature of 41°C (106°F).

The sealed lead-acid battery is rated at a 5-hour (0.2) and 20-hour (0.05C) discharge. Longer discharge times produce higher capacity readings because of lower losses. The lead-acid performs well on high load currents.

Absorbed Glass Mat Batteries (AGM)

The AGM is a newer type sealed lead-acid that uses absorbed glass mats between the plates. It is sealed, maintenance-free and the plates are rigidly mounted to withstand extensive shock and vibration. Nearly all AGM batteries are recombinant, meaning they can recombine 99% of the oxygen and hydrogen. There is almost no water is loss.

The charging voltages are the same as for other lead-acid batteries. Even under severe overcharge conditions, hydrogen emission is below the 4% specified for aircraft and enclosed spaces. The low self-discharge of 1-3% per month allows long storage before recharging. The AGM costs twice that of the flooded version of the same capacity. Because of durability, German high performance cars use AGM batteries in favor of the flooded type.

Advantages

Inexpensive and simple to manufacture.  Mature, reliable and well-understood technology - when used correctly, lead-acid is durable and provides

dependable service.

The self-discharge is among the lowest of rechargeable battery systems.

Capable of high discharge rates.

Limitations

Low energy density - poor weight-to-energy ratio limits use to stationary and wheeled applications. Cannot be stored in a discharged condition - the cell voltage should never drop below 2.10V.

Allows only a limited number of full discharge cycles - well suited for standby applications that require only occasional deep discharges.

lead content and electrolyte make the battery environmentally unfriendly. 

Transportation restrictions on flooded lead acid - there are environmental concerns regarding spillage.

Thermal runaway can occur if improperly charged.