July 2004

SPH Ni-Cd batteryTechnical manual

1. Introduction 3

2. Electrochemistry of nickel-cadmium batteries 4

3. Construction features of the SPH battery 53.1 Positive plate 53.2 Negative plate 53.3 Plate tab 53.4 Separator 53.5 Terminal pillars 53.6 Electrolyte 53.7 Vent system 63.8 Cell container 6

4. Operating features 74.1 Capacity 74.2 Cell voltage 74.3 Internal resistance 74.4 Effect of temperature on performance 74.5 Short-circuit values 84.6 Open circuit loss 84.7 Cycling 94.8 Effect of temperature on lifetime 94.9 Water consumption and gas evolution 10

5. Battery sizing principles in standby applications 115.1 The voltage window 115.2 Discharge profile 115.3 Temperature 115.4 State of charge or recharge time 115.5 Ageing 125.6 Floating effect 125.7 Number of cells in a battery 12

6. Battery charging 136.1 Constant voltage charging methods 136.2 Charge acceptance 136.3 Charge efficiency 146.4 Temperature effects 14

7. Special operating factors 157.1 Electrical abuse 157.2 Mechanical abuse 15

8. Installation and operating instructions 168.1 Receiving the shipment 168.2 Storage 168.3 Installation 168.4 Commissioning 178.5 Charging in service 188.6 Topping-up 188.7 Periodic maintenance 188.8 Changing electrolyte 18

9. Maintenance of the SPH in service 199.1 Cleanliness/mechanical 199.2 Water replenishment 199.3 Capacity check 199.4 Recommended maintenance procedure 20

10. Disposal and recycling 21

Contents

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The Saft SPH Ni-Cd batterycombines the best features ofreliable battery power with thetangible benefit of exceptionallylow maintenance.

Specified where a rapiddischarge characteristic is vitalfor critical engine starting dutiesand UPS applications, SPH isfast becoming the battery ofchoice to safeguard today’s hightechnology industries.

By reliably delivering high powerwithin a low voltage window andneeding only minimalmaintenance even in harsh andremote locations, SPH meetsthe demands set by computer-controlled process systems,hospitals, telecommunicationsstations, on-shore, off-shore, andanywhere where a long life, lowcycle cost is important.

The sintered/pbe plateconstruction and potassiumhydroxide electrolyte at the heartof SPH allow to have a normal

operating temperature from–20°C to +50°C (–4°F to+122°F), and accept extremetemperatures from –50°C to+70°C (–58°F to +158°F),without risk of plate degradationand the catastrophe of suddenfailure.

When used as recommendedthe SPH can operate for up to20 years without the need forwater replenishment. Thebattery’s electricalcharacteristics enable it totolerate ripple currents,overcharging, over-dischargingand voltage reversal.

This manual provides acomprehensive guide to theconstruction, installation, andoperation of your SPH battery.Saft are at the forefront of Ni-Cdbattery technology developmentand always have available expertadvice or practical help toensure the smooth running ofyour installation.

1. Introduction

3

discharge2 NiOOH + 2H2O + Cd 2 Ni(OH)2 + Cd(OH)2

charge

The nickel-cadmium battery usesnickel hydroxide as the activematerial for the positive plate,cadmium hydroxide for thenegative plate.

The electrolyte is an aqueoussolution of potassium hydroxidecontaining small quantities oflithium hydroxide to improvecycle life and high temperatureoperation. The electrolyte is onlyused for ion transfer, it is notchemically changed or degradedduring the charge/dischargecycle. In the case of the lead acidbattery, the positive and negativeactive materials chemically reactwith the sulphuric acid electrolytewith a resulting ageing process.

The support structure of bothplates is steel. This is unaffectedby the electrochemistry and

retains its characteristicsthroughout the life of the cell. Inthe case of the lead acid battery,the basic structure of bothplates are lead and lead oxidewhich play a part in theelectrochemistry of the processand are naturally corrodedduring the life of the battery.

During discharge the trivalentnickel hydroxide is reduced todivalent nickel hydroxide and thecadmium at the negative plateforms cadmium hydroxide.On charge, the reverse reactiontakes place until the cell potentialrises to a level where hydrogenis evolved at the negative plateand oxygen at the positive platewhich results in water loss.

Unlike the lead acid battery,there is little change in the

electrolyte density during chargeand discharge. This allows largereserves of electrolyte to beused without inconvenience tothe electrochemistry of thecouple.

Thus, through itselectrochemistry, the nickel-cadmium battery has a morestable behavior than the leadacid battery so giving it a longerlife, superior characteristics anda greater resistance againstabusive conditions.

Nickel-cadmium cells have anominal voltage of 1.2 volts (V).

The charge/discharge reaction is as follows :

2. Electrochemistry ofnickel-cadmium batteries

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3.1 Positive plateThe positive plate used in the cellis of the sintered type. This isobtained by chemicalimpregnation of nickel hydroxideinto a porous nickel structure,which is obtained by sinteringnickel powder onto a thin,perforated, nickel-plated strip.

3.2 Negative plateThe negative electrode is aplastic-bonded cadmiumelectrode, produced with acontinuous process. This involvesblending together the activematerial, binder and additives,continuously spreading this ontoa perforated nickel-plated steelsubstrate, drying and, finally,passing the coated band throughrollers for dimensioning.

3.3 Plate tabThe electrodes are seam weldedto the plate tabs so producing acontinuous interface between thetwo components. This ensureshigh current transfer andmaximum strength. The platetab material is nickel-plated steeland the plate tab thickness ischosen to ensure a satisfactorycurrent carrying capabilityconsistent with the application.

3.4 SeparatorThe separator consists of asandwich of micro-porouspolymer and non-woven feltwhich maintains an optimizeddistance between the electrodes.The separator system has beendeveloped to give an optimumbalance between performance,reliability and long life.

3.5 Terminal pillarsThe material used for theterminal pillars (copper or steel)and the number of terminals percell are chosen as a function ofthe intended application. Theterminal pillars are nickel-plated.

3.6 ElectrolyteThe electrolyte used in thesintered/pbe range, which is asolution of potassium hydroxideand lithium hydroxide, isoptimized to give the bestcombination of performance, life,energy efficiency and a widetemperature range.

The concentration of the standardelectrolyte is such as to allow thecell to be operated down totemperature extremes as low as –20°C (–4°F) and as high as+50°C (+122°F). This allows thevery high temperature fluctuationfound in certain regions to beaccommodated.

For very low temperatures aspecial high density electrolytecan be used.

It is an important considerationof the sintered/pbe range, andindeed all nickel-cadmiumbatteries, that the electrolyteconcentration does not changeduring charge and discharge. Itretains its ability to transfer ionsbetween the cell plates,irrespective of the charge level.

In most applications theelectrolyte will retain itseffectiveness for the life of thebattery and will never needreplacing.

The electrode material is lessreactive with the alkalineelectrolyte (nickel-cadmiumsecondary batteries) than withacid electrolytes (lead acidsecondary batteries).Furthermore, during chargingand discharging in alkalinebatteries the electrolyte worksmainly as a carrier of oxygen orhydroxyl ions from one electrodeto the other; hence thecomposition or the concentrationof the electrolyte does notchange noticeably.

In the charge/discharge reactionof the nickel-cadmium battery, thepotassium hydroxide is notmentioned in the reaction

3. Construction featuresof the SPH battery

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Container

Separator

Large electrolytereserve with visible level

Plastic-bonded negativeelectrode

Saft cells fulfill allrequirements specified byIEC 60623

Sintered positiveelectrode

formula. A small amount of wateris produced during the chargingprocedure (and consumed duringthe discharge). The amount is notenough to make it possible todetect if the battery is charged ordischarged by measuring thedensity of the electrolyte.

Once the battery has been filledwith the correct electrolyte atthe battery factory there is noneed to check the electrolyte

density periodically. The densityof the electrolyte in the batteryeither increases or decreases asthe electrolyte level dropsbecause of water electrolysis orevaporation or rises at topping-up. Interpretation of densitymeasurements is difficult andcould be misleading.

3.7 Vent systemThe SPH is fitted with a specialflame-arresting flip-top vent togive an effective and safe ventingsystem.

3.8 Cell containerThe SPH range is available inpolypropylene or in flameretardent polyamid (nylon).

Flame-arrestingflip-top vent

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4

4.1 CapacityThe SPH electrical capacity israted in ampere-hours (Ah) and isthe quantity of electricity at +20°C(+68°F) which it can supply for a5 hour discharge to 1.0 V afterbeing fully charged at 7.5 hoursat 0.2 C5A. This figure is inagreement with the IEC 60623standard.

According to the IEC 60623(Edition 4), 0.2 C5A is alsoexpressed as 0.2 I t A. Thereference test current (I t) isexpressed as:

Cn Ah1 h

where:Cn is the rated capacity declared

by the manufacturer in ampere-hours (Ah),and

n is the time base in hours (h) for which the rated capacity is declared.

4.2 Cell voltageThe cell voltage of nickel-cadmium cells results from theelectrochemical potentials of thenickel and the cadmium activematerials in the presence of thepotassium hydroxide electrolyte.The nominal voltage for thiselectrochemical couple is 1.2 V.

4.3 Internal resistanceThe internal resistance of a cellvaries with the type of serviceand the state of charge and is,therefore, difficult to define andmeasure accurately.

The most practical value fornormal applications is thedischarge voltage response to achange in discharge current.

The typical internal resistance ofan SPH cell when measured atnormal temperature is 40 mΩper Ah capacity. For example,the internal resistance of SPH 150 is given by:

40 150

The above figure is for fullycharged cells. For lower statesof charge the values increase.

For cells 50% discharged theinternal resistance is about 20%higher and when 90%discharged it is about 80%higher. The internal resistance ofa fully discharged cell has verylittle meaning. Reducing thetemperature also increases theinternal resistance and, at 0°C,(+32°F) the internal resistance isabout 15% higher.

4.4 Effect of temperature on performance

Variations in ambienttemperature affect theperformance of SPH and this isallowed for in the batteryengineering.

Low temperature operation hasthe effect of reducing theperformance but the highertemperature characteristics aresimilar to those at normaltemperatures. The effect oftemperature is more marked athigher rates of discharge.

4. Operating features

I t A =

= 0.27 mΩ

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The factors which are required insizing a battery to compensatefor temperature variations aregiven in a graphical form in Figure1 for an operating temperaturerange of –20°C to +40°C (–4°F to+104°F). For use attemperatures outside this range,contact Saft for advice.

4.5 Short-circuit valuesThe minimum short-circuit valuefor the SPH cell is 30 times theampere-hour capacity.

An approximate calculation of theshort-circuit current for a givencell is 1.8 x cell dischargecurrent to 0.65 V for 1 s.

The SPH battery is designed towithstand a short-circuit currentof this magnitude for manyminutes without damage.

4.6 Open circuit lossThe state of charge of SPH onopen circuit stand slowlydecreases with time due to self-discharge. In practice thisdecrease is relatively rapid duringthe first two weeks but thenstabilizes to about 2% per monthat +20°C (+68°F).

The self-discharge characteristicsof a nickel-cadmium cell areaffected by the temperature. Atlow temperatures the chargeretention is better than at normaltemperature and so the opencircuit loss is reduced.

However, the self-discharge issignificantly increased at highertemperatures.

The open circuit loss for the SPHcell for a range of temperaturesis shown in Figure 2.

Figure 1 – Temperature de-rating factor for different rate discharge

Figure 2 – Capacity loss on open circuit stand

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4.7 CyclingThe SPH range is designed towithstand the wide range ofcycling behavior encountered instationary applications. This canvary from low depth ofdischarges to discharges of upto 100% and the number ofcycles that the product will beable to provide will depend on thedepth of discharge required.

The less deeply a battery iscycled, the greater the numberof cycles it is capable ofperforming before it is unable toachieve the minimum designlimit. A shallow cycle will give many tens of thousands of operations, whereas a deepcycle will give fewer operations.

Figure 3 gives typical values forthe effect of depth of dischargeon the available cycle life, and it isclear that when sizing the batteryfor a cycling application, thenumber and depth of cycles havean important consequence on thepredicted life of the system.

4.8 Effect of temperature on lifetime

The SPH range is designed as atwenty year life product, but as with every battery system,increasing temperature reducesthe expected life.

However, the reduction in lifetimewith increasing temperature isvery much lower for the nickel-cadmium battery than the leadacid battery.

The reduction in lifetime for thenickel-cadmium battery, and for

comparison, a high quality leadacid battery is shown graphicallyin Figure 4. The values for thelead acid battery are as suppliedby the industry and found in IEEEdocumentation.

Figure 4: Effect of temperature on lifetime

Figure 3: Typical cycle life versus depth of discharge

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In general terms, for every 9°C(16.2°F) increase in temperatureover the normal operatingtemperature of +25°C (+77°F),the reduction in service life for anickel-cadmium battery will be20%, and for a lead acid batterywill be 50%. In high temperaturesituations, therefore, specialconsideration must be given todimensioning the nickel-cadmiumbattery. Under the sameconditions, the lead acid batteryis not a practical proposition,due to its very short lifetime. Thevalve-regulated lead acid battery(VRLA), for example, which has alifetime of about 7 years undergood conditions, has thisreduced to less than 1 year, ifused at +50°C (+122°F).

4.9 Water consumption and gas evolution

During charging, more ampere-hours are supplied to the batterythan the capacity available fordischarge. These additionalampere-hours must be providedto return the battery to the fullycharged state and, since theyare not all retained by the celland do not all contribute directlyto the chemical changes to theactive materials in the plates,they must be dissipated in someway. This surplus charge, orovercharge, breaks down thewater content of the electrolyte

into oxygen and hydrogen, andpure distilled water has to beadded to replace this loss.

Water loss is associated with thecurrent used for overcharging. Abattery which is constantly cycled,i.e. is charged and discharged ona regular basis, will consumemore water than a battery onstandby operation.

In theory, the quantity of waterused can be found by the Faradicequation that each ampere-hourof overcharge breaks down0.366 cm3 of water. However, inpractice, the water usage will beless than this as the overchargecurrent is also needed tosupport self-discharge of theelectrodes.

The overcharge current is afunction of both voltage and

temperature and so both havean influence on the consumptionof water.

Figure 5 gives typical waterconsumption values over a rangeof temperature at floatingvoltage of 1.41 V/cell.

The gas evolution is a function ofthe amount of water electrolyzedinto hydrogen and oxygen and ispredominantly given off at theend of the charging period. Thebattery gives off no gas during anormal discharge.

The electrolysis of 1 cm3 ofwater produces 1865 cm3 ofgas mixture and this gas mixtureis in the proportion of 2/3

hydrogen and 1/3 oxygen. Thusthe electrolysis of 1 cm3 ofwater produces about 1243 cm3

of hydrogen.

Figure 5: Water replenishment intervals at 1.41 V/cell

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5

There are a number of methodswhich are used to size nickel-cadmium batteries for standbyfloating applications. Theseinclude the IEEE 1115 method ofthe Institute of Electrical andElectronics Engineers. Thismethod is approved andrecommended by Saft for thesizing of nickel-cadmiumbatteries. Sizing methods musttake into account multipledischarges, temperaturede-rating, performance afterfloating and the voltage windowavailable for the battery. Allmethods have to use methods ofapproximation and some do thismore successfully than others.

A significant advantage of thenickel-cadmium batterycompared to a lead acid battery,is that it can be fully dischargedwithout any inconvenience interms of life or recharge. Thus,to obtain the smallest and leastcostly battery, it is an advantageto discharge the battery to thelowest practical value in order toobtain the maximum energy fromthe battery.

The principle sizing parameterswhich are of interest are:

5.1 The voltage windowThis is the maximum voltage andthe minimum voltage at thebattery terminals acceptable forthe system. In battery terms, themaximum voltage gives thevoltage which is available tocharge the battery, and theminimum voltage gives the lowestvoltage acceptable to the systemto which the battery can bedischarged. In discharging thenickel-cadmium battery, the cellvoltage should be taken as low aspossible in order to find the mosteconomic and efficient battery.

5.2 Discharge profileThis is the electricalperformance required from thebattery for the application. It maybe expressed in terms ofamperes for a certain duration,or it may be expressed in termsof power, in watts or kW, for acertain duration. Therequirement may be simply onedischarge or many discharges ofa complex nature.

5.3 TemperatureThe maximum and minimumtemperatures and the normalambient temperature will havean influence on the sizing of thebattery. The performance of abattery decreases withdecreasing temperature andsizing at a low temperatureincreases the battery size.Temperature de-rating curvesare produced for all cell types toallow the performance to berecalculated.

5.4 State of charge or recharge time

Some applications may requirethat the battery shall give a fullduty cycle after a certain timefollowing the previous discharge.The factors used for this willdepend on the depth ofdischarge, the rate of discharge,and the charge voltage andcurrent. A requirement for ahigh state of charge does notjustify a high charge voltage ifthe result is a high end ofdischarge voltage.

5. Battery sizing principlesin standby applications

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5.5 AgeingSome customers require a valueto be added to allow for theageing of the battery over itslifetime. This may be a valuerequired by the customer, forexample 10%, or it may be arequirement from the customerthat a value is used which willensure the service of the batteryduring its lifetime. The value tobe used will depend on thedischarge rate of the battery andthe conditions under which thedischarge is carried out.

5.6 Floating effectWhen a nickel-cadmium cell ismaintained at a fixed floatingvoltage over a period of time,there is a decrease in thevoltage level of the dischargecurve. This effect begins afterone week and reaches itsmaximum in about 3 months. It can only be eliminated by a fulldischarge/charge cycle, and itcannot be eliminated by a boostcharge. It is therefore necessaryto take this into account in anycalculations concerning batteriesin float applications.

This is used in the IEEE sizingmethod and the published datafor SPH.

5.7 Number of cells in a battery

As mentioned earlier, due to thevoltage window available, thecharge voltage and the end ofdischarge voltage have to bechosen to give the bestcompromise between chargingtime and final end of dischargevoltage.

If the difference in publishedperformance for a cell for thesame time of discharge but todifferent end voltages isexamined, it is clear that there isa significant improvement inperformance as the end ofdischarge voltage is reduced.

As the charge voltage and theend of discharge voltage arelinked by the voltage window, it isan advantage to use the lowestcharge voltage possible in orderto obtain the lowest end ofdischarge voltage.

The number of cells in thebattery is determined by themaximum voltage available in thevoltage window, i.e. the chargevoltage.

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6

6.1 Constant voltage charging methods

Batteries in stationary applicationsare normally charged by a constantvoltage float system and this can betwo types: the two-rate type wherethere is an initial constant voltagecharge followed by a lower floatingvoltage; or a single rate floatingvoltage.

The single voltage charger isnecessarily a compromise between avoltage high enough to give anacceptable charge time and lowenough to give a low water usage.However, it does give a simplercharging system and accepts asmaller voltage window than the two-rate charger.

The two-rate charger has an initialhigh voltage stage to charge thebattery followed by a lower voltagemaintenance charge. This allows thebattery to be charged quickly, and yet,have a low water consumption due tothe low voltage maintenance level.

For float applications the values usedfor SPH range for single and two-ratecharge systems are:

Single rate charge:1.41± 0.01V/cell at +20°C (+68°F)

Dual rate charge:High rate:1.45 ± 0.01 V/cell at +20°C (+68°F)Float charge:1.40 ± 0.01 V/cell at +20°C (+68°F)

In case of frequent cycling, therecommended charge voltages are:

Single rate charge:1.45 - 1.55 V/cell at +20°C (+68°F)

Dual rate charge:High rate:1.45 - 1.60 V/cell at +20°C (+68°F)Float charge:1.40 ± 0.01 V/cell at +20°C (+68°F)

To minimize the water usage, it isimportant to use a low chargevoltage, and so the minimum voltagefor the single level and the two levelcharge voltage is normallyrecommended value. This also helpswithin a voltage window to obtain thelowest, and most effective, end of discharge voltage.

6.2 Charge acceptanceA discharged cell will take a certaintime to achieve a full state of charge.

Figure 6 gives the capacity availablefor typical charging voltagesrecommended for the SPH rangeduring the first 24 hours of chargefrom a fully discharged state.

This graph gives the recharge timefor a current limit of 0.2 C5 amperes.Clearly, if a lower value for the currentis used, e.g. 0.1 C5 amperes, thenthe battery will take longer to charge.

If a higher current is used then it willcharge more rapidly. This is not ingeneral a pro rata relationship due tothe limited charging voltage.

If the application has a particularrecharge time requirement then thismust be taken into account whencalculating the battery.

6. Battery charging

Figure 6: Available capacity for typical charging voltages

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6.3 Charge efficiencyThe charge efficiency of thebattery is dependent on the stateof charge of the battery and thetemperature. For much of itscharge profile, it is recharged ata high level of efficiency.

In general, at states of chargeless than 80% the chargeefficiency remains high, but asthe battery approaches a fullycharged condition, the chargingefficiency falls off. This isillustrated graphically in Figure 7.

6.4 Temperature effectsAs the temperature increases,the electrochemical behaviorbecomes more active, and so forthe same floating voltage, thecurrent increases. As thetemperature is reduced then thereverse occurs. Increasing thecurrent increases the waterloss, and reducing the currentcreates the risk that the cell willnot be sufficiently charged. Forstandby application, it is normallynot required to compensate thecharging voltage with thetemperature. However if waterconsumption is of main concern,temperature compensation

should be used if the battery isoperating at high temperaturesuch as +35°C (+95°F). At lowtemperature (< 0°C/+32°F),there is a risk of poor chargingand it is recommended to adjustthe charging voltage or tocompensate the charging voltagewith the temperature.

Value of the temperaturecompensation: –2 mV/°C(–1.1 mV/°F) starting from anambient temperature of +20°Cto +25°C (+68°F to +77°F).

Figure 7: Charge efficiency as a function of state of charge

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7

7.1 Electrical abuseRipple effectsThe nickel-cadmium battery istolerant to high ripple and willaccept ripple currents of up to0.2 C5 A I eff. In fact, the onlyeffect of a high ripple current isthat of increased water usage.Thus, in general, anycommercially available chargeror generator can be used forcommissioning or maintenancecharging of the SPH. Thiscontrasts with the VRLA batterywhere relatively small ripplecurrents can cause batteryoverheating, and will reduce lifeand performance.

Over-dischargeIf more than the designedcapacity is taken out of a batterythen it becomes deep-dischargedand reversed. This is consideredto be an abuse situation fora battery and should be avoided.

In the case of lead acid batteriesthis will lead to failure of thebattery and is unacceptable.

The SPH battery is designed tomake recovery from thissituation possible.

OverchargeIn the case of an SPH batterywith its generous electrolytereserve, a small degree ofovercharge over a short periodwill not significantly alter themaintenance period. In the caseof excessive overcharge, waterreplenishment is required, butthere will be no significant effecton the life of the battery.

7.2 Mechanical abuseShock loadThe SPH battery concept hasbeen tested to IEC 68-2-29(bump tests at 5 g, 10 g and 25 g)and IEC 77 (shock test 3 g),where g = acceleration.

Vibration resistanceThe SPH battery concept hasbeen tested to IEC 77 for 2 hours at 1 g, whereg = acceleration.

External corrosionAll external metal componentsare nickel-plated or stainlesssteel, protected by a neutralvaseline and a rigid plastic cover.

7. Special operating factors

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8. Installation andoperating instructions

Important recommendations

Never allow an exposed flameor spark near the battery,particularly while charging.

Never smoke while performingany operation on the battery.

For protection, wear rubbergloves, long sleeves, andappropriate splash goggles orface shield.

The electrolyte is harmful toskin and eyes. In the event ofcontact with skin or eyes, washimmediately with plenty ofwater. If eyes are affected,flush with water, and obtainimmediate medical attention.

Remove all rings, watches andother items with metal partsbefore working on the battery.

Use insulated tools. Avoid static electricity and take

measures for protectionagainst electric shocks.

Discharge any possible staticelectricity from clothing and/ortools by touching an earth-connected part “ground” beforeworking on the battery.

8.1 Receiving the shipmentUnpack the battery immediatelyupon arrival. Do not overturn thepackage. Transport seals arelocated under the cover of thevent plug.

The battery is normally shippedfilled, discharged and ready forinstallation.

The battery must never be chargedwith the plastic transport seals inplace as this can cause permanentdamage.

8.2 StorageStore the battery indoors in a dry,clean and cool location (+0°C to+30°C/+32°F to +86°F) location.

Do not store in unopenedpacking crates. The lid and thepacking material on top of thecells must be removed.

Make sure that the transportseals remain in place duringstorage.

Do not store in direct sunlight orexposed to excessive heat.

A battery delivered dischargedand filled may be stored for manyyears before it is installed.

A battery delivered exceptionally80% charged (for startingapplication) must not be storedfor more than 3 months(including transport).

8.3 Installation8.3.1 LocationInstall the battery in a dry and cleanroom. Avoid direct sunlight, strongdaylight and heat.

The battery will give the bestperformances and maximum servicelife when the ambient temperature isbetween +10°C to +30°C (+50°F to+86°F).

The batteries can be fitted on tostands, floor-mounted or fitted intocabinets.

Local standards or codes normallydefine the mounting arrangementsof batteries, and these must befollowed if applicable. However, ifthis is not the case, the followingcomments should be used as aguide.

When mounting the battery, it is desirable to maintain an easyaccess to all cells; they should be situated in a readily availableposition.

Distances between stands, andbetween stands and walls, should besufficient to give good access to thebattery.

The overall weight of the battery mustbe considered and the load bearingon the floor taken into account in theselection of the batteryaccommodation.

If the battery is enclosed in a cabinetor other such enclosed space, it isimportant to provide sufficient spaceto disperse the gases given off duringcharging, and also to minimizecondensation.

It is recommended that at least200 mm be allowed above cell tops,to ensure easy access duringinspection and water replenishment,and that enough space is allowedbetween cabinet walls and the batteryto avoid any risk of short-circuits. Flip-top vents may be turned through180° to achieve the most convenientposition for water replenishment.

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8.3.2 VentilationNote that special regulations forventilation may be valid in yourarea depending on theapplication.

When the battery is housed in acubicle or enclosed compartment,it is necessary to provide adequateventilation.

During the last part of high-ratecharging, the battery is emittinggases (oxygen and hydrogenmixture).

If it is required to establish thatthe ventilation of the battery roomis adequate, then it is necessary tocalculate the rate of evolution ofhydrogen to ensure that theconcentration of hydrogen gas inthe room is kept within safe limits.

The theoretical safe limit forhydrogen concentration is 4%.However, some standards call formore severe levels than this, andlevels as low as 1% aresometimes required.

To calculate the ventilationrequirements of a battery room,the following method can be used:

1 Ah of overcharge breaks down0.366 cm3 of water, and 1 cm3 ofwater produces 1.865 liters ofgas in the proportion 2/3 hydrogenand 1/3 oxygen. Thus 1 Ah ofovercharge produces 0.42 liters ofhydrogen.

Therefore, the volume of hydrogenevolved from a battery per hour= number of cells x charge currentx 0.42 liters or= number of cells x charge currentx 0.00042 m3

The volume of hydrogen found by

this calculation can be expressedas a percentage of the totalvolume of the battery room, andfrom this, the number of airchanges required to keep theconcentration of hydrogen below acertain level can be calculated.

Example:A battery of 98 cells, type SPH 70on a two step, two tier stand, isplaced in a room of dimensions 2 m x 2 m x 3 m. The chargingsystem is capable of charging at0.1 C5 and so the chargingcurrent is 7 A. The volume ofhydrogen evolved per hour in this,the worst, case is:98 x 7 x 0.00042 m3 = 0.29 m3

The total volume of the room is2 x 2 x 3 = 12 m3

Approximate volume of battery andstand does not exceed 1m3, andso, the volume of free air in theroom is 11 m3. Therefore, theconcentration of hydrogen gasafter charging for 1 hour at fullgassing potential at 0.1 C5 will be:

Thus, to maintain a maximumconcentration of 3% (for example),the air in the room will needchanging

In practice, a typical figure fornatural room ventilation is about2.5 air changes per hour, and so,in this case, it would not benecessary to introduce any forcedventilation.

In a floating situation, the currentflowing is very much lower thanwhen the cell is being charged,and the gas evolution is minimal; it

may be calculated in the same wayusing typical floating currents.

8.3.3 MountingVerify that cells are correctlyinterconnected with theappropriate polarity. The batteryconnection to load should be withnickel-plated cable lugs.Recommended torques forconnecting nuts are:• M 10 = 10 ± 2 N.m• M 12 = 15 ± 2 N.m

The connectors and terminal nutsshould be corrosion-protected bycoating with a film of neutralvaseline.

Remove the transport seals andclose the vents.

8.3.4 ElectrolyteThe electrolyte to be used is: E4.

When checking the electrolytelevels, a fluctuation in levelbetween cells is not abnormal andis due to the different amounts ofgas held in the separator of eachcell. The level should be at least15 mm above the minimum markand there is normally no need toadjust it.

When the cells are charged, theelectrolyte level can be above thehigh level mark.

8.4 CommissioningVerify that the ventilation isadequate during this operation.

For filled and discharged cellsstored up to 1 year, a commissioning charge isnormally not required and thecells are ready for immediateuse. If full performances arenecessary immediately, acommissioning charge as

2.6 3

= around 1 time per hour.

0.2911

= 2.6 %

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mentioned in the section below is recommended.

For cells stored more than 1 year, a commissioning chargeis necessary:

• constant current charge ispreferable: 8 h at 0.2 C5A.When the charger maximumvoltage setting is too low tosupply constant currentcharging, divide the battery intotwo parts to be chargedindividually.

• constant potential charge:1.50 V/cell minimum.

Charging time: 24 h if thecharging current is limited to 0.2 C5A, 48 h if the chargingcurrent is limited to 0.1 C5A.

Please note: if cells have beenstored in charged conditions formore than 3 months (includingtransport), or if cells have beenstored for a few years or showdifficulties in recoveringperformance, constant currentcharging becomes necessary andthe following values arerecommended:a) 15 h charge at 0.2 C5Ab) discharge at 0.2 C5A down to

1.0 V/cellc) 8h charge at 0.2 C5Ad) the battery is ready for use.

8.5 Charging in serviceAt continuous parallel operation,the battery is on continuouscharge and has only occasionaldischarges.

Recommended charging voltage(+20°C to +25°C/+68°F to +77°F): for dual charge level:• Float level: 1.40 ± 0.01 V/cell• High level: 1.45 ± 0.01 V/cell

for single charge level:1.41 ± 0.01 V/cell

In case of frequent deepdischarges (cycling), the chargingvoltage values should beincreased. See section 6.1.

For use at temperature outside+10°C to +30°C (+50°F to +86°F),the correcting factor for chargevoltage is –2 mV/°C/cell(–1.1 mV/°F/cell).

8.6 Topping-upNo electrolyte level measurementis necessary if you use a Saftfilling-pistol, which allows thecorrect level to be obtained by asimple nozzle setting. See nozzlelengths in operating andinstruction sheet.

If a filling-pistol is not available, theelectrolyte level can be checked bytransparence or measured in thecase of flame retardantcontainers. Insert a transparentglass or plastic tube (alkaliresistant, 5 to 6 mm in diameter)vertically into the cell vent until ittouches the top of the plates.Close the top end of the tube byputting a finger on it and removethe tube from the cell.

The height of the liquid in the tubeindicates the electrolyte level abovethe plates.

Level (mm)high low

SPH 16 B to SPH 47 B 25 5SPH 11 25 5SPH/FR 16 to SPH/FR 52 55 5SPH/FR 60 to SPH/FR 80 70 5SPH/FR 90 to SPH/FR 190 65 5SPH/FR 220 to SPH/FR 320 55 5

8.7 Periodic maintenance Keep the battery clean using

only water. Do not use a wirebrush or solvents of any kind.Vent caps can be rinsed inclean water if necessary.

Check visually the electrolytelevel. Never let the level fallbelow the minimum level mark.Use only distilled or deionizedwater to replenish. Experiencewill tell the time intervalbetween topping-up.Note:Once the battery has been filledwith the correct electrolyte atthe battery factory, there is noneed to check the electrolytedensity periodically.Interpretation of densitymeasurements is difficult andcould be misleading.

Check every two years that allconnectors are tight. Theconnectors and terminal nutsshould be corrosion-protectedby coating with neutral vaseline.

Check the charging voltage. It isof great importance that therecommended charging voltageremains unchanged. Thecharger should be checked atleast once a year. High waterconsumption of the battery isusually caused by impropervoltage setting of the charger.

8.8 Changing electrolyteDue to the sintered electrodeplastic-bonded technology, it is notnecessary to change theelectrolyte during the lifetime ofthe cell.

18

In a correctly designed standbyapplication, SPH requires theminimum of attention. However,it is good practice with anysystem to carry out aninspection at least once per year,or at the recommended waterreplenishment interval, to ensurethat the charger, the battery andthe auxiliary electronics are allfunctioning correctly.

When this inspection is carriedout, it is recommended thatcertain procedures should becarried out to ensure that thebattery is maintained in a goodstate.

9.1 Cleanliness/mechanicalCells must be kept clean and dryat all times, as dust and dampcause current leakage. Terminalsand connectors should be keptclean, and any spillage duringmaintenance should be wiped offwith a clean cloth. The battery canbe cleaned, using water. Do notuse a wire brush or a solvent ofany kind. Vent caps can be rinsedin clean water, if necessary.

Check that the flame-arrestingvents are tightly fitted and thatthere are no deposits on thevent cap.

Terminals should be checked fortightness, and the terminals andconnectors should be corrosion-

protected by coating with a thinlayer of neutral grease or anti-corrosion oil agreed by Saft.

9.2 Water replenishmentCheck the electrolyte level. Neverlet the level fall below the lowerMIN mark. Use only approveddistilled or deionized water toreplenish. Do not overfill the cells.

Excessive consumption of waterindicates operation at too high avoltage or too high atemperature. Negligibleconsumption of water, withbatteries on continuous lowcurrent or float charge, couldindicate under-charging. Areasonable consumption of wateris the best indication that abattery is being operated underthe correct conditions. Anymarked change in the rate ofwater consumption should beinvestigated immediately. Thewater replenishment interval canbe calculated as described insection 4.9. However, it isrecommended that, initially,electrolyte levels should bemonitored monthly to determinethe frequency of topping-uprequired for a particularinstallation.

Saft has a full range of waterreplenishment equipmentavailable to aid this operation.

9.3 Capacity checkElectrical battery testing is notpart of normal routinemaintenance, as the battery isrequired to give the back-upfunction and cannot be easilytaken out of service.

However, if a capacity test of thebattery is needed, the followingprocedure should be followed:

a) Charge of 7.5 h at 0.2 C5A

b) Discharge the battery at therate of 0.2 C5A to a finalaverage voltage of 1.0 V/cell(i.e. 92 V for a 92 cell battery)

c) Charge of 7.5 h at the samerate used in a)

d) Discharge at the same rateused in a), measuring andrecording current, voltage andtime every quarter hour. Thisshould be continued until afinal average voltage of 1.0 V/cell is reached. Theoverall state of the battery canthen be seen, and if individualcell measurements are taken,the state of each cell can beobserved.

9. Maintenance of the SPH in service

19

9.4 Recommendedmaintenance procedureIn order to obtain the best fromyour battery, the followingmaintenance procedure isrecommended.

It is also recommended that amaintenance record be kept whichshould include a record of thetemperature of the battery room.

Yearly

check charge voltage settings

check cell voltages

check float current of the battery

Every 2 years

clean cell lids and battery area

check torque values

protect terminal nuts and terminals with neutral vaseline

Every 5 years or as required

capacity check

As required

replenish with water according to defined period (depend on float

voltage, cycles and temperature)

20

In a world where autonomoussources of electric power areever more in demand, Saftbatteries provide anenvironmentally responsibleanswer to these needs.Environmental management liesat the core of Saft’s business andwe take care to control everystage of a battery’s life cycle interms of potential impact.Environmental protection is ourtop priority, from design andproduction through end-of-lifecollection, disposal and recycling,where more than 99% of batterymetals are recycled.

Our respect for the environmentis complemented by an equalrespect for our customers. Weaim to generate confidence in ourproducts, not only from afunctional standpoint, but also interms of the environmentalsafeguards that are built into theirlife cycle. The simple and uniquenature of the battery componentsmake them readily recyclable andthis process safeguards valuablenatural resources for futuregenerations.

In partnership with collectionagencies worldwide, Saft organizesretrieval from pre-collection pointsand the recycling of spent Saftbatteries. Information about Saft’scollection network can be found onour web site :

Ni-Cd batteries must not bediscarded as harmless wasteand should be treated carefully inaccordance with local andnational regulations. Your Saftrepresentative can assist withfurther information on theseregulations and with the overallrecycling procedure.

10. Disposal and recycling

www.saftbatteries.com

NEWBATTERIES

BATTERYUSE

SPENTBATTERIES

CADMIUMPLATES

DISTILLATION

PURECADMIUM

STEELSCRAP

STEELWORKS NICKEL

PLATES

DISMANTLING

21

AfricaExport sales dpt,FranceTel: +33 1 49 93 19 18Fax: +33 1 49 93 19 56

ArgentinaEnergia Alcalina,Buenos AiresTel: +54 11 4334 9034/35Fax: +54 11 4342 5024

AustraliaSaft Australia Pty Ltd,Seven HillsTel: +61 2 9674 0700Fax: +61 2 9620 9990

AustriaStatron GmbH, WienTel: +43 1 617 40 60Fax: +43 1 617 40 60/40

BelgiumAEG Belgium SA, BrusselsTel: +32 2 529 6543Fax: +32 2 529 6449

BrazilFSE (Fábrica de Sistemas de Energia) Ltda.,Sao PauloTel: +55 11 6100 6304Fax: +55 11 6100 6338

Canada Please contact USA office

ChileTechno Parts Ltda.,SantiagoTel: +56 (2) 249 6060

ChinaSaft TradingTel: +86 21 5866 7935Fax: +86 21 5866 6403

Czech RepublicSaft Ferak a.s.,PragueTel: +420 281 080 120Fax: +420 281 080 119

DenmarkScansupply A/S,BirkeroedTel: +45 45 82 50 90Fax: +45 45 82 54 40

FinlandHansaBattery Oy,EspooTel: +358 9 260 65 292Fax: +358 9 260 65 299

FranceDivision France,BagnoletTel: +33 1 49 93 19 18Fax: +33 1 49 93 19 64

GermanySaft Batterien GmbH,NürnbergTel: +49 911 94 174-0Fax: +49 911 426 144

Hong KongSaft Ltd,KowloonTel: +852 2796 99 32Fax: +852 2798 06 19

India sub continentExport sales dpt,SwedenTel: +46 491 680 00Fax: +46 491 681 80

ItalySaft Batterie Italia S.r.l.,Segrate (Milano)Tel: +39 02 89 28 07 47Fax: +39 02 89 28 07 62

JapanSumitomo Corp.,TokyoTel: +81 3 5144 9082Fax: +81 3 5144 9267

KoreaEnersys Korea Co. Ltd,Kyunggi-DoTel: +82 2501 0033Fax: +82 2501 0034

MexicoTroop y Compania, SA de CV,MexicoTel: +52 55 50 82 10 30Fax: +52 55 50 82 10 39

Middle EastSaft Nife ME Ltd,Limassol, CyprusTel: +357 25 820040Fax: +357 25 748492

NetherlandsSaft Batteries B.V.,HaarlemTel: +31 23 750 5720Fax: +31 23 750 5725

NorwaySaft AS, OsteraasTel: +47 6716 4160Fax: +47 6716 4170

RussiaZAO Alcatel, MoscowTel: +7 095 937 0967Fax: +7 095 937 0906

SingaporeSaft Batteries Pte Ltd,SingaporeTel: +65 6512 1500Fax: +65 6749 7282

SpainSaft Baterias S.L.San Sebastian de los ReyesTel: +34 916 59 34 80Fax: +34 916 59 34 90

SwedenSaft AB,OskarshamnTel: +46 491 680 00Fax: +46 491 681 80

SwitzerlandStatron AG,MägenwilTel: +41 62 887 4 887Fax: +41 62 887 4 888

United KingdomSaft Ltd,Tel: +44 1279 772 550Fax: +44 1279 420 909

USASaft America Inc.,North Haven (CT)Tel: +1 203 239 4718Fax: +1 203 234 7598

VenezuelaCorporación INTELEC C.A.,CaracasTel: +58 212 9631122

Committed to a clean environmentSaft takes seriously its responsibility to safeguard the environment.At several sites worldwide, more than 99% of metals contained in the

battery are recycled. This process safeguards valuable naturalresources and is a service to customers that Saft will continueto offer for future generations.To locate the nearest collection site, visit www.saftbatteries.com

SaftIndustrial Battery Group12, rue Sadi Carnot93170 Bagnolet – FranceTel: +33 1 49 93 19 18Fax: +33 1 49 93 19 64

www.saftbatteries.com

Doc N˚ 21112-2-0704Edition: July 2004Data in this document is subject to change withoutnotice and becomes contractual only after writtenconfirmation.

Photo credit: Saft, Photodisc, Digitalvision

Société anonyme au capital de 31 944 000RCS Bobigny B 383 703 873

Prepared by Arthur Associates Limited.