battery types used for auxiliary power

7/23/2019 Battery Types Used for Auxiliary Power

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Different types of battery used for auxiliaryDifferent types of battery used for auxiliarypower supply in substations and powerpower supply in substations and powerplantsplants

Different types of battery used for auxiliary power supply in substations and power plants

In industrial or substation applications mainly three types of batteries are usedIn industrial or substation applications mainly three types of batteries are used

namely:namely:

Vented / Flooded Lead Acid batteriesVented / Flooded Lead Acid batteries1.

SealedSealed free batteries/Valve Regulated Lead Acidfree batteries/Valve Regulated Lead Acid2.

Nickel Cadmium (Ni-cd) batteriesNickel Cadmium (Ni-cd) batteries3.

For UPS applications batteries are the most popular and hence are widely used. Hence, inFor UPS applications batteries are the most popular and hence are widely used. Hence, in

this detailing, mainly emphasize has been put on these type of batteries.this detailing, mainly emphasize has been put on these type of batteries.

Vented / Flooded Lead Acid BatteriesVented / Flooded Lead Acid Batteries

There are two types for vented or flooded lead acid batteries namely tubular and Plante.There are two types for vented or flooded lead acid batteries namely tubular and Plante.

maintenancemaintenance

erytypes used f or auxi l i arypower suppl yi n substati ons and power pl an... http://el ectr i cal -engi neeri ng-portal .com/di f f erent-type

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The difference between the two is the construction.The difference between the two is the construction.

For tubular battery normal life is 8-10 years. TheFor tubular battery normal life is 8-10 years. The

Plante battery is both mechanically and electricallyPlante battery is both mechanically and electrically

more durable. The normal life for Plante batteries ismore durable. The normal life for Plante batteries is

15-20 years. Because this type of battery generates15-20 years. Because this type of battery generates

corrosive fumes when charging and because thecorrosive fumes when charging and because the

sulfuric acid electrolyte does evaporate to somesulfuric acid electrolyte does evaporate to some

extent, these batteries must be used in a specialextent, these batteries must be used in a special

room, which is well ventilated to the outside and keptroom, which is well ventilated to the outside and kept

away from delicate electronic equipments.away from delicate electronic equipments.

It needs separate room/racks with acid proof tiles forIt needs separate room/racks with acid proof tiles for

installation. Because of evaporation, it needs regularinstallation. Because of evaporation, it needs regular

maintenance to check specific gravity, to add watermaintenance to check specific gravity, to add water

and acid. These batteries can withstand highand acid. These batteries can withstand high

temperature, voltage, and deep discharge withtemperature, voltage, and deep discharge with

minimum damage to itself. A notice should beminimum damage to itself. A notice should be

exhibited in the battery room prohibiting smoking andexhibited in the battery room prohibiting smoking and

use of naked flames. These batteries cannot beuse of naked flames. These batteries cannot be

transported in charged condition and therefore needtransported in charged condition and therefore need

charging at site.charging at site.

Typical initial charging of the battery will take about 55 to 90 hours. Nominal cell voltage isTypical initial charging of the battery will take about 55 to 90 hours. Nominal cell voltage is

2V/cell. The charger for this battery should be able to provide the first charge at 2.6 to 2.72V/cell. The charger for this battery should be able to provide the first charge at 2.6 to 2.7

V/cell.V/cell.

These types of batteries are typically used for UPS Systems of very high rated capacity,These types of batteries are typically used for UPS Systems of very high rated capacity,


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typically engaged for plant application, wherein maintenance and space is not really antypically engaged for plant application, wherein maintenance and space is not really an

issue.issue.

Sealed Maintenance Free batteries (SMF)Sealed Maintenance Free batteries (SMF)

These are also known asThese are also known as

batteries. Thesebatteries. These

batteries are the most popular for usage with UPSbatteries are the most popular for usage with UPS

systems for computer or commercial application. Beingsystems for computer or commercial application. Being

sealed, these batteries do not emit any fumes andsealed, these batteries do not emit any fumes and

hence can be very well installed next to electronichence can be very well installed next to electronic

equipment. These batteries also can be housed in aequipment. These batteries also can be housed in a

close enclosure if necessary. These batteries are alsoclose enclosure if necessary. These batteries are also

maintenance free and avoid any hassles of checkingmaintenance free and avoid any hassles of checking

specific gravity, adding water or acid, etc.specific gravity, adding water or acid, etc.

These batteries have a relatively lesser life of approx.These batteries have a relatively lesser life of approx.

3-5 years. The life expectancy typically depends on3-5 years. The life expectancy typically depends on

the number of charge/discharge cycle experienced by the batteries and the ambientthe number of charge/discharge cycle experienced by the batteries and the ambient

temperature in which the batteries are used. These batteries are primarily the mosttemperature in which the batteries are used. These batteries are primarily the most

popular for commercial applications due to Install and forget approach.popular for commercial applications due to Install and forget approach.

The Performance and service life of these batteries can be maximized byThe Performance and service life of these batteries can be maximized by

observing the following guidelines:observing the following guidelines:

Permissible operating temperature range of SMF batteries isPermissible operating temperature range of SMF batteries is 15 deg C to 50 deg C15 deg C to 50 deg C,,

but using within an operating range 5 C to 35 C will extend service life. Below 15 deg C,but using within an operating range 5 C to 35 C will extend service life. Below 15 deg C,

the battery changes its chemical composition and cannot hold a charge. You will enjoythe battery changes its chemical composition and cannot hold a charge. You will enjoy

longer service life, if batteries are operated in ambient temperature range oflonger service life, if batteries are operated in ambient temperature range of 20 deg C to20 deg C to

25 deg C (68F to 77F)25 deg C (68F to 77F). At lower temperature they have longer life and lower capacity. At lower temperature they have longer life and lower capacity

while at higher temperature they have higher capacity and lower life.while at higher temperature they have higher capacity and lower life.

A good rule of thumb when determining battery service life in relation to temperatureA good rule of thumb when determining battery service life in relation to temperature

is that for every 8.3 deg C (15F) average annual temperature above 25 deg C (77F), theis that for every 8.3 deg C (15F) average annual temperature above 25 deg C (77F), the

life of the battery is reduced by 50%. Therefore warranty of the battery should be ideallylife of the battery is reduced by 50%. Therefore warranty of the battery should be ideally

reduced to 50% for every 8.3 deg C (15F) increase in operating temperature above 25 degreduced to 50% for every 8.3 deg C (15F) increase in operating temperature above 25 deg

C (77F).C (77F).

SMF batteries are designed to have aSMF batteries are designed to have a float voltage of 2.3 V/cellfloat voltage of 2.3 V/cell. This means that a. This means that a

12 V battery (with 6 internal cells) has a float voltage of 13.8 Volts. Most of the battery12 V battery (with 6 internal cells) has a float voltage of 13.8 Volts. Most of the battery

Valve Regulated Lead Acid (VRLA)Valve Regulated Lead Acid (VRLA)


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manufacturers recommend float voltage of 2.25 2.3 volts per cell. When there are moremanufacturers recommend float voltage of 2.25 2.3 volts per cell. When there are more

cells (generally >120) in series, to compensate for higher temperatures, float voltagecells (generally >120) in series, to compensate for higher temperatures, float voltage

should be decreased by approx. 3 mV per cell per deg C above 25 deg C. It should beshould be decreased by approx. 3 mV per cell per deg C above 25 deg C. It should be

increased by the same amount when operated at a temperature less than 25 deg C toincreased by the same amount when operated at a temperature less than 25 deg C to

avoid undercharge. The Cutoff voltage is 1.67 V/cell for high rate of discharge (avoid undercharge. The Cutoff voltage is 1.67 V/cell for high rate of discharge (

It is recommended that SMF batteries should not be left in totally discharged stateIt is recommended that SMF batteries should not be left in totally discharged state

more than 72 hrs. The batteries may get partially or fully damaged due to SULPHATION ifmore than 72 hrs. The batteries may get partially or fully damaged due to SULPHATION if

charging does not start within 72 Hrs from totally discharged state. Sulphation is thecharging does not start within 72 Hrs from totally discharged state. Sulphation is the

formation of lead sulphate on negative plates which acts as an insulator and has aformation of lead sulphate on negative plates which acts as an insulator and has a

detrimental effect on charge acceptance.detrimental effect on charge acceptance.

In normal float / equalize use (2.25 to 2.35V/cell), gas generated inside battery isIn normal float / equalize use (2.25 to 2.35V/cell), gas generated inside battery is

recombined into negative plates, and return to water content of the electrolyte. Thusrecombined into negative plates, and return to water content of the electrolyte. Thus

electrical capacity is not lost because of this recombination. There is no need to addelectrical capacity is not lost because of this recombination. There is no need to add

external water, but due the corrosion of the electrodes battery will eventually lose capacity.external water, but due the corrosion of the electrodes battery will eventually lose capacity.

At ambient temperature of 30 40 deg C, the shelf life of batteries isAt ambient temperature of 30 40 deg C, the shelf life of batteries is 5-6 months5-6 months

onlyonly. A freshening charge must be given to the batteries every 6 months, if needed to be. A freshening charge must be given to the batteries every 6 months, if needed to be

stored for longer periods. Batteries should be kept in dry, cool place. At ambientstored for longer periods. Batteries should be kept in dry, cool place. At ambient

temperature of 20 deg C (68F), the self-discharge rate is 3-4% (approx.) of rated capacitytemperature of 20 deg C (68F), the self-discharge rate is 3-4% (approx.) of rated capacity

per month. The self-discharge rate varies with ambient temperature.per month. The self-discharge rate varies with ambient temperature.

SMF batteries are equipped with a safe, low pressure venting system, whichSMF batteries are equipped with a safe, low pressure venting system, which

operates at 7 psi to 10 psi (can vary slightly from manufacturer to manufacturer),operates at 7 psi to 10 psi (can vary slightly from manufacturer to manufacturer),

automatically releasing excess gas in the event that gas pressure rises to a level aboveautomatically releasing excess gas in the event that gas pressure rises to a level above

the normal rate ensuring no excessive buildup of gas in the batteries. Resealing isthe normal rate ensuring no excessive buildup of gas in the batteries. Resealing is

automatic once the pressure is returned to normal.automatic once the pressure is returned to normal.

Cyclic life of the battery depends on ambient operating temperature, the dischargeCyclic life of the battery depends on ambient operating temperature, the discharge

rate, the depth of discharge, and the manner in which the battery is recharged. The mostrate, the depth of discharge, and the manner in which the battery is recharged. The most

important factor is the depth of discharge. At a given discharge rate and time, theimportant factor is the depth of discharge. At a given discharge rate and time, the

shallower the depth of discharge, the longer is the cyclic life.shallower the depth of discharge, the longer is the cyclic life.

Failure mode at the end of life includes:Failure mode at the end of life includes:

Capacity decreaseCapacity decrease1.

Internal short circuitInternal short circuit2.

Damage to container/lidDamage to container/lid3.

Terminal corrosionTerminal corrosion4.

Reduced open circuit voltage.Reduced open circuit voltage.5.


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The IEEE defines B (Bend of useful life) for a UPS battery as being the pointThe IEEE defines B (Bend of useful life) for a UPS battery as being the point

when it can no longer supply 80 percent of its rated capacity in ampere-hours (AH). Thewhen it can no longer supply 80 percent of its rated capacity in ampere-hours (AH). The

relationship between AH capacity and runtime time is not linear, a 20% reduction inrelationship between AH capacity and runtime time is not linear, a 20% reduction in

capacity results in a much greater reduction in runtime. When battery reaches 80% of itscapacity results in a much greater reduction in runtime. When battery reaches 80% of its

ratedrated , the aging process accelerates and the battery should be replaced. Some, the aging process accelerates and the battery should be replaced. Some

UPS/ Battery manufacturers define B (Bend of useful life) for a UPS battery when batteryUPS/ Battery manufacturers define B (Bend of useful life) for a UPS battery when battery

capacity reachescapacity reaches 50-60%50-60%of its rated capacity.of its rated capacity.

Mixed use of batteries with different capacities, different makes should be avoidedMixed use of batteries with different capacities, different makes should be avoided

as it will cause accelerated aging of the whole string.as it will cause accelerated aging of the whole string.

If two or more battery groups are to be used, connected in parallel, they must beIf two or more battery groups are to be used, connected in parallel, they must be

connected to the UPS through lengths of wires, cables or busbars that have the same loopconnected to the UPS through lengths of wires, cables or busbars that have the same loop

line resistance as each other. This makes sure that each parallel bank of batteriesline resistance as each other. This makes sure that each parallel bank of batteries

presents the same impedance to the UPS as any other of the parallel banks therebypresents the same impedance to the UPS as any other of the parallel banks thereby

ensuring correct equalization of the source to allow for maximum energy transfer to theensuring correct equalization of the source to allow for maximum energy transfer to theUPS load.UPS load.

The normal life SMF battery will supportThe normal life SMF battery will support approx. 200 charge/discharge cyclesapprox. 200 charge/discharge cycles atat

25 deg C (77F) and 100% depth of discharge.25 deg C (77F) and 100% depth of discharge.

The term B (The term B (Bend of useful lifeBend of useful life) for a UPS battery refers to the fact that these) for a UPS battery refers to the fact that these

batteries do not require fluid. But preventive maintenance like checking for cracks andbatteries do not require fluid. But preventive maintenance like checking for cracks and

deformation of the container & lid, electrolyte leakage/spills tightening of the connectiondeformation of the container & lid, electrolyte leakage/spills tightening of the connection

etc, particularly for higher AH capacity batteries should be done to prevent any damage.etc, particularly for higher AH capacity batteries should be done to prevent any damage.

Nickel Cadmium Batteries (Ni-Cd)Nickel Cadmium Batteries (Ni-Cd)

Ni-cd batteries do emit hydrogen and oxygen gas, products of electrolysis, but there areNi-cd batteries do emit hydrogen and oxygen gas, products of electrolysis, but there are

no corrosive gases as lead acid batteries, so these can be installed near electronicno corrosive gases as lead acid batteries, so these can be installed near electronic

equipment. Water consumption is relatively low and so therefore maintenance is low.equipment. Water consumption is relatively low and so therefore maintenance is low.

Normal service life is 20-25 years. These are most expensive of the various types ofNormal service life is 20-25 years. These are most expensive of the various types of

batteries previously discussed. Initial cost may be approximately three times that of leadbatteries previously discussed. Initial cost may be approximately three times that of lead

acid battery depending upon their AH capacity.acid battery depending upon their AH capacity.

These batteries do not experience the severe shortening of life when operated at elevatedThese batteries do not experience the severe shortening of life when operated at elevated

temperatures and perform better at low temperatures than do the lead acid batteries.temperatures and perform better at low temperatures than do the lead acid batteries.

Nominal cell voltage is 1.2 V/cell. The battery chargers and inverters have to be designedNominal cell voltage is 1.2 V/cell. The battery chargers and inverters have to be designed

to operate with low end cell cutoff voltages and higher recharging voltages needed forto operate with low end cell cutoff voltages and higher recharging voltages needed for

such batteries.such batteries.

These batteries occasionally demand boost charging and typically find their applicationsThese batteries occasionally demand boost charging and typically find their applications

wherein UPSs support critical equipment in hazardous environment such as chemical,wherein UPSs support critical equipment in hazardous environment such as chemical,

capacitycapacity


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fertilizer, cement industry.fertilizer, cement industry.

Merits/demeritsMerits/demerits

As spelled earlier, all the above discussed types of batteries have their own merits andAs spelled earlier, all the above discussed types of batteries have their own merits and

demerits. Let us now look at them individually.demerits. Let us now look at them individually.

A) Vented / flooded Lead acid batteriesA) Vented / flooded Lead acid batteries

MeritsMerits

Most economical among three types of batteries.Most economical among three types of batteries.1.

Life is higher than SMF batteries.Life is higher than SMF batteries.2.

Robust- not much sensitive to temperature.Robust- not much sensitive to temperature.3.

DemeritsDemerits

Needs periodic maintenance- twice a month.Needs periodic maintenance- twice a month.1.

Emits corrosive fumes.Emits corrosive fumes.2.

Needs special battery room with acid proof tilling.Needs special battery room with acid proof tilling.3.

Cannot be transported in charged condition, initial charging takes 55 to 90 hours.Cannot be transported in charged condition, initial charging takes 55 to 90 hours.4.

Needs specially trained persons for handling due highly hazardous sulphuric acid.Needs specially trained persons for handling due highly hazardous sulphuric acid.5.

B) Sealed maintenance free batteries / Valve Regulated Lead AcidB) Sealed maintenance free batteries / Valve Regulated Lead Acid

MeritsMerits

No maintenance as far as water filling, specific gravity check etc is concerned.No maintenance as far as water filling, specific gravity check etc is concerned.1.

Can be shipped in charged conditions so ready to use.Can be shipped in charged conditions so ready to use.2.

User friendly.User friendly.3.

DemeritsDemerits

Leaving batteries in discharged state for longer life will reduce life significantly or canLeaving batteries in discharged state for longer life will reduce life significantly or can

damage them permanently.damage them permanently.

1.

Very sensitive to temperatureVery sensitive to temperature2.

Service life lowest among the three typesService life lowest among the three types3.

Costlier than flooded / vented lead acid batteryCostlier than flooded / vented lead acid battery4.

C) Nickel Cadmium (Ni-cd) batteriesC) Nickel Cadmium (Ni-cd) batteries

MeritsMerits


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Moderate maintenanceModerate maintenance1.

Higher service lifeHigher service life2.

less sensitive to temperatureless sensitive to temperature3.

Fumes not corrosive so can be installed near electronic equipmentFumes not corrosive so can be installed near electronic equipment4.

DemeritsDemerits

Most expensive among three typesMost expensive among three types1.

Cannot be transported in charged conditions.Cannot be transported in charged conditions.2.

Compatibility with respect to charger and inverter needed to be considered.Compatibility with respect to charger and inverter needed to be considered.3.

Summary of Techno-Commercial Analysis between Ni-Cd & LeadSummary of Techno-Commercial Analysis between Ni-Cd & Leadacid Batteriesacid Batteries


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No.No. DescriptionDescription Ni-CdNi-Cd Lead acidLead acid RemarksRemarks

11 Reliability CriteriaReliability Criteria Worst case failure isWorst case failure is

cell short circuit.cell short circuit.

Result is reducedResult is reduced

performance. Theperformance. The

battery will continuebattery will continue

to support theto support thesystem.system.

Worst case failureWorst case failure

is cell open circuit.is cell open circuit.

Result is completeResult is complete

loss of battery,loss of battery,

known as suddenknown as sudden

death, resulting indeath, resulting inan unpredictedan unpredicted

system failure.system failure.

This point makesThis point makes

NiCd to be superiorNiCd to be superior

in terms of purposein terms of purpose

22 Requirement ofRequirement of

Air-Conditioning &Air-Conditioning &

additional cost ofadditional cost of

Electrical EnergyElectrical Energy

NilNil YesYes Additional Cost dueAdditional Cost due

to Air conditioningto Air conditioning

equipment andequipment and

running cost-Forrunning cost-For

VRLAVRLA

33 Battery Life asBattery Life asclaimed by UKclaimed by UK

manufacturersmanufacturers

(Industrial(Industrial

Batteries)Batteries)

20 Years20 Years 5-7 Years5-7 Years Replacing cost ofReplacing cost ofVRLA after every 5-7VRLA after every 5-7

years will involveyears will involve

manufacturing costmanufacturing cost

escalation duringescalation during

that year. Eg.at 6ththat year. Eg.at 6th

year, 12th year andyear, 12th year and

18th year.18th year.

44 Battery CostBattery Cost Approximately 3Approximately 3

times than VRLAtimes than VRLA

55 Relative CostsRelative Costs

Initial & Life CycleInitial & Life Cycle

Ni-Cd cells have aNi-Cd cells have a

higher initial costhigher initial cost

than lead acid butthan lead acid but

superior lifetime andsuperior lifetime and

characteristics, givingcharacteristics, giving

a lower life cycle costa lower life cycle cost

in many applications.in many applications.

Lead Acid has aLead Acid has a

low initial cost butlow initial cost but

a restricteda restricted

lifetime. In manylifetime. In many

applications theyapplications they

can have a poorcan have a poor

life cycle cost.life cycle cost.

66 Physical SizePhysical Size Ni-Cd cells areNi-Cd cells aregenerally larger thangenerally larger than

VRLA cells.VRLA cells.

In terms of Ah,In terms of Ah,Lead acid (VRLA)Lead acid (VRLA)

is the mostis the most

compact battery.compact battery.

77 Water ToppingWater Topping OccasionallyOccasionally

RequiredRequired

Not RequiredNot Required


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Summary of Comparison between tubular flooded (ordinarySummary of Comparison between tubular flooded (ordinaryLead-acid) battery with SMF Lead Acid BatteryLead-acid) battery with SMF Lead Acid Battery


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No.No. Tubular Lead Acid batteryTubular Lead Acid battery VRLA BatteryVRLA Battery

11 Tubular positive Plates:Tubular positive Plates:

The positive active material is held in aThe positive active material is held in a

polyester tube. This does not allow thepolyester tube. This does not allow the

materials to shed during charge-materials to shed during charge-

discharge cycling resulting in long cyclicdischarge cycling resulting in long cyclic

life- minimum 1200 cycles at 80 % depthlife- minimum 1200 cycles at 80 % depthof discharge.of discharge.

Flat pasted positive plates:Flat pasted positive plates:

The positive active material is a pasteThe positive active material is a paste

form pasted over a lead alloy grid. Thisform pasted over a lead alloy grid. This

results in a shorter cyclic life compared toresults in a shorter cyclic life compared to

tubular construction.- minimum 500tubular construction.- minimum 500

cycles at 80% depth of dischargecycles at 80% depth of discharge

22 Electrolyte:Electrolyte: Stationary batteries of UPSStationary batteries of UPS

and Power plant back up works on lowand Power plant back up works on low

specific gravity (1.200) electrolyte andspecific gravity (1.200) electrolyte and

larger in volume. This results in lesslarger in volume. This results in less

corrosion of grids and longer life. Thecorrosion of grids and longer life. The

larger volume keeps the batterylarger volume keeps the battery

comparatively cooler which also adds tocomparatively cooler which also adds to

life.life.

Electrolyte:Electrolyte:VRLA batteries work on highVRLA batteries work on high

specific gravity electrolyte (1.280 tospecific gravity electrolyte (1.280 to

1.300) and less volume. The cells get1.300) and less volume. The cells get

heated up during charging and high rateheated up during charging and high rate

discharges which affects the service life.discharges which affects the service life.

33 Separators:Separators:Micro porous poly ethyleneMicro porous poly ethylene

separators are used. This permits the ionseparators are used. This permits the ion

movement and positive to negative platemovement and positive to negative plate

separation.separation.

Separators:Separators:Adsorptive glass matAdsorptive glass mat

separators are used in these batteriesseparators are used in these batteries

with a closer spacing between thewith a closer spacing between the

positive and negative plates. Chances ofpositive and negative plates. Chances of

cell shorting are therefore more.cell shorting are therefore more.

44 Charging compatibility:Charging compatibility:TubularTubular

stationary lead acid batteries can bestationary lead acid batteries can be

charged with constant current andcharged with constant current andconstant voltage mode. Floodedconstant voltage mode. Flooded

electrolyte batteries can withstand moreelectrolyte batteries can withstand more

abuses during charging. Water lost inabuses during charging. Water lost in

electrolyte during such abusiveelectrolyte during such abusive

overcharging could be easily made upovercharging could be easily made up

manually by periodic top-up. Laggingmanually by periodic top-up. Lagging

cells could be brought to normal life bycells could be brought to normal life by

an extended equalizing charging withoutan extended equalizing charging without

significantly affecting the other cells.significantly affecting the other cells.

Charging compatibility:Charging compatibility: VRLA batteriesVRLA batteries

require constant voltage charging with arequire constant voltage charging with a

specified limit only specifically to avoidspecified limit only specifically to avoidovercharging. If by any chance, theovercharging. If by any chance, the

charging conditions are altered, thecharging conditions are altered, the

battery will get heated up which willbattery will get heated up which will

deteriorate the battery life. Though theredeteriorate the battery life. Though there

is no need to top-up due to theis no need to top-up due to the

recombination principle, it is not alwaysrecombination principle, it is not always

100% efficient, so some water loss100% efficient, so some water loss

during use is not avoidable. This resultsduring use is not avoidable. This results

in a further increase in electrolyte specificin a further increase in electrolyte specificgravity and life reduction. Equalizinggravity and life reduction. Equalizing

(Extended) charging in VRLA batteries(Extended) charging in VRLA batteries

results in some cells getting heated upresults in some cells getting heated up

and life reduction.and life reduction.


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Share with engineers //Share with engineers //

55 Containers:Containers:We use transparent SANWe use transparent SAN

containers. The electrolyte level is easilycontainers. The electrolyte level is easily

seen for topping up needs and ease ofseen for topping up needs and ease of

maintenance. Low maintenance.maintenance. Low maintenance.

Not applicable:Not applicable:Cannot monitorCannot monitor

ElectrolyteElectrolyte

66 Need for temperature control:Need for temperature control:Due toDue to

the large electrolyte volume thethe large electrolyte volume the

temperature of the cells generally do nottemperature of the cells generally do notrise abnormally during charging. No needrise abnormally during charging. No need

for Air conditioning.for Air conditioning.

Need for temperature control:Need for temperature control: TheThe

close packing arrangement andclose packing arrangement and

compactness of the stack in the cellcompactness of the stack in the cellassembly rises the temperature sharplyassembly rises the temperature sharply

during charging. Due to this, VRLAduring charging. Due to this, VRLA

battery manufacturers invariablybattery manufacturers invariably

recommend the need for air conditionedrecommend the need for air conditioned

environment for the batteryenvironment for the battery

compartments. This adds to the cost ofcompartments. This adds to the cost of

maintenance.maintenance.

Recommended EE stuff //Recommended EE stuff //

About Author //About Author //

Asif Eqbal -Asif Eqbal - Bachelor of Engineering in Electrical & ElectronicsBachelor of Engineering in Electrical & Electronics

engineering, from Manipal University, (Karnataka), India in 2006.engineering, from Manipal University, (Karnataka), India in 2006.

Presently involved in the design of EHV outdoor substation andPresently involved in the design of EHV outdoor substation and

coal fired thermal power plants for more than seven years. Motto ofcoal fired thermal power plants for more than seven years. Motto of

joining EEP as a contributor is to share my little engineeringjoining EEP as a contributor is to share my little engineeringexperience and help the budding engineers in bridging theexperience and help the budding engineers in bridging the

conspicuous gap between academics and Industrial practice. Ifconspicuous gap between academics and Industrial practice. If

you have knowledge, let others light their candles with it, so that people who are genuinelyyou have knowledge, let others light their candles with it, so that people who are genuinely

interested in helping one another develop new capacities for action; it is about creatinginterested in helping one another develop new capacities for action; it is about creating

timeless learning processes".timeless learning processes".

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