ML20151V170

Forwards Responses to NRC 880627 Questions Re Single Cell Battery Charging Sys.Util Has No Formal Trending Program That Reviews Individual Cell Data

ML20151V170
Person / Time
Site:	Summer
Issue date:	08/15/1988
From:	Bradham O SOUTH CAROLINA ELECTRIC & GAS CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
TAC-68045, NUDOCS 8808220171
Download: ML20151V170 (15)

Text

4 a th Cm.line Electric & Gas Comp:ny e S. 8 adhm Jenkinsville, SC 29035 Nuctur Operations (t03) 345-4040 SCE&G e ABCnMt W August 15, 1988 Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

Virgil C. Summer Nuclear Station Docket No. 50/395 Operating License No. NPF-12 Single Cell Battery Charging (TAC No. 68045)

Gentlemen:

Attached are the responses to the NRC staff request for additional information regarding the use of single cell battery chargers at the Virgil C. Summer Nuclear Station. These responses were requested by the staff in a letter dated June 27, 1988.

Should you desire additional information or desire a meeting on this issue, please call at your convenience.

Very truly yours, W

0. S. Bradham MDB/0SB:df Attachment c: D. A. Nauman/0. W. Dixon, Jr./T. C. Nichols, Jr./J. G. Connelly, Jr.

E. C. Roberts G. O. Percival W. A. Williams, Jr. R. L. Prevatte J. N. Grace J. B. Knotts, Jr.

J. J. Hayes, Jr. M. D. Blue General Managers D. O. Hicks C. A. Price /R. M. Campbell, Jr. NSRC i R. B. Clary NPCF l K. E. Nodland J. C. Snelson RTS (NRR880003)

File (819.38)

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, Attachment to Documsnt Control Desk August 15, 1988 Page 1 of 5 RESPONSES TO NRC QUESTIONS ON THE SINGLE CELL BATTERY CHARGING SYSTEM 1

OVESTION 1 What programs are in place (such as a trending program) to determine if a cell (s) that repeatedly requires equalization should be replaced? l

RESPONSE

Existing programs that monitor battery status; are surveillance testing, planned preventative maintenance tasks and non-conformance evaluations. 1 If a problem with an individual cell exists, the problem would be identified and resolved under these programs. There is no formal trending program that reviews individual cell data.

1 OVESTION 2 l How many hours on the average during the year is it expectcd that the 40 volt charger will be connected to either safety-related battery? Is there a limit on the number of hours that the 40 volt charger is permitted to be connected?

RESPONSE I It is estimated that the single cell battery charger (SCBC) would be  ;

connected no longer than 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> per year on each safety-related battery l bank; however, no limit has been placed on the number of hours the SCBC  !

can be connected to the battery banks. There is a seven day Technical Specification surveillance requirement on the battery banks, but in order to perform this surveillance, the SCBC would have to be disconnected from l the safety-related battery bank.

QUESTION 3 If an insulation blanket is used over the safety-related battery bank while placing an equalization charge using the 40 volt charger, what procedures insure that the battery does not become overheated due to the blanket?

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RESPONSE

l Electrical Maintenance Procedure (EMP) 115.004, "Individual Cell Charging Procedure," is being revised to not allow rubber blankets to be placed in such a manner that would block ventilation passages.

OVESTION 4 What protection is there to detect and isolate a high impedance fault between the 40 volt battery charger and the isolation fuses if the fault limits the current to a value less than the fuse rating?

RESPONSE

Cabling for the SCBC was designed to minimize faults. The cables between the SCBC and the isolation fuse panels are run totally in conduit thus

Attechmen; to Docum:nt Control Dask August 15, 1988 Page 2 of 5 minimizing the possibility of mechanical damage. The positive and negative pole c-bles are purchased nuclear-safety-related, and are run in separate conduits except for the short runs between the SCBC, a terminal box and the charging cables disconnect switches. The cables in the isolation fuse panels and disconnect switches are arranged and spaced so as to maintain a minimum of 5" spacing where possible between cables of the opposite de pole.

The 125V de system is an ungrounded system. One cable failing to ground would not cause a fault / overload condition. Both the positive and negative cables must fail for a fault condition.

The 125V de system is equipped with ground indicating lights in the main control room. Depending on the number of cells under equalizing charge by the SCBC and the fault impedance, there may be a discernable difference between the intensity of the two ground indicating lights prompting operator action. (Note that normal SCBC operation will not produce an intensity difference between the ground indicating lights).

Battery cell degradation due to a high impedance fault is improbable due to the following:

Positive and negative cables must fail simultaneously.

Cables are run in conduit only.

The majority of the cable length is run in separate conduits for each pole.

Cables are separated by a minimum 5" spacing where possible in the disconnect switches and fuse panels.

The probability of a high impedance fault itself is low.

Fault detection by the ground indicating lights.

It is therefore concluded that the concern regarding high impedance faults is adequately addressed.

QUESTION 5 The 10 CFR 50.59 assessment of the 40 volt charger states that the charger will not act as a short because the output resistors plus the circuit resistance will limit the current to an insignificant amount. What is considered to be an insignificant amount?

RESPONSE

In the case of a loss of input ac to the SCBC, the worst case current from the battery bank to the SC8C has been calculated to be 7.9 amps due to the effect of the output resistors and circuit resistance. This worst case value was based on the following conservative assumptions.

. Attachment to Documsnt Control Desk August 15, 1988 Page 3 of 5 The 125V de charger is in service with the volts per cell assumed to be the maximum float value of 2.25V.

The number of cells connected to the SCBC is the maximum allowable of 17.

• Fuse, disconnect switch, terminal block and other cable contact resistances are assumed to be negligible.

The calculated maximum current of 7.9 amps will not damage any equipment.

The drain on the battery would be 47.4 amp-hours (AH) (6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> maximum between SCBC checks x 7.9 amps) with the 125 V de charger in service.

47.4 AH is 4.5% of the connected cell's 1050 AH capacity. This is less than the battery reserve capacity of 9.32% for the 1A battery and 1ti.96%

for the IB battery.

The 47.4 AH battery cell discharge is a worst case drain since no credit is taken for any recharging occurring as a result of the 125V de charger remaining in service. The trickle current from the 125V de charger is assumed to be negligible; therefore, the amp-hour input (recharge) to a battery cell is also assumed to be negligible.

If input ac is lost to both the SCBC and the 125V dc charger, the current drain drops to 7.4 amps due to lower volts per cell. The battery design is to provide power for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> without charging. The drain on the battery from the SCBC in this case is 14.8 AH (2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> x 7.4 amps) which is 1.4% of a cell's 1050 AH capacity.

O'JESTION 6 The 10 CFR 50.59 assessment states that each cell of the battery can withstand 2.9 volts 9 52.5A for approximately 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. However, the isolation fuses are rated at 150 amperes. What protects the battery against equalization currents between 52.5 and 150 amperes in the event that the voltage regulator controls partially fail? j

RESPONSE

If a battery cell is fully charged and at 2.9V, the current passed through the cell in an attempt by the charger to raise the cell voltage past 2.9V will generate heat and breakdown water through electrolysis. The battery vendor, C&O Batteries, Inc., calculated that a cell passing 150 amps would take approximately eight hours to reach the cell's low water level if it was initially at its proper water level. Be?ow the low water level, cell damage could occur and outgassing could be a problem as the water level eventually drops belcw the cell's flame arrestor rendering it no longer functional.

Therefore to assure a battery cell will not be damaged due to a maintained equalizing current of 150 amps, a battery check is required every 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. This 6 hour6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> figure provides margin relative to the 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> required to reach a battery cell's low water level noted previously.

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. Attachm:nt to Documsnt Control Desk August 15, 1988 Page 4 of 5 00ESTION 7 I It is understood that administrative controls will be used to check every six hours against an overvoltage to the battery cells while using the 40 volt charger. What ascessment has been made to determine the effect nf a six hour maximum overvoltage condition?

RESPONSE

In a calculation similar to the one in the previous question, C&D Batteries has calculated that a battery cell can withstand a 2.9V and 52.5 amp condition for up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Therefore, an adequate safety margin exists between the 6 hour6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> battery check and the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> withstand expectancy. (NOTE: Due to a cell's physical characteristics, 2.9V is the maximum that can appear across its terminals.)

OUESTION 8 What procedural steps are followed to insure that the station battery and its individual cells are operable after removing the 40 volt charger?

RESPONSE

Electrical Maintenance Procedure (EMP) 115.004, "Individual Cell Charging Procedure," controls the use of the SCBC including administrative requirements such as battery cable separation criteria and equipment time interval checks to ensure the operability of the station battery. Upon removal of the SCBC from the station battery, EMP-115.004 requires a set of battery data be obtained using EMP-115.011. "Battery Inspection" to determine the as-left condition of the station battery. Acceptance criteria for individual cell voltages (22.13V dc), electrolyte level, electrolyte specific gravity, and electrolyte temperature (a65'F) is contained in EMP-115.011.

QUESTION 9 Have the fuse cabinets, cable racks and their mountings (in the battery rooms) been seismically qualified? In particular, what assurance is there that the cable racks will not tear loose and directly or indirectly fault the battery?

RESPONSE

The SCBC system has been seismically designed and installed. The SCBC stand, cable rack, local panels, disconnect switches, terminal box, and fuses in local panels and components in other panels were all seismically mounted. The conduit clamps, expansion bolts. SCBC stand and cable rack steel and hardware were purchased nuclear-safety-related.

Based on the preceding items, seismic or anti-falldown concerns have been adequately addressed in the SCBC system design.

. Attachment to Document Control Dask August 15, 1988 Page 5 of 5 00ESTION 10 Please send a copy of the pages from the instruction manuals 1MS948-245 and 300 that discuss the conditions for beginning or ending and equalization charge.

RESPONSE

The instruction manual pages requested by the NRC are attached, l

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SECTION VI l OPERATION 3 1

6.0 OPERATION 6.2 EQUALIZING CHARGE 6.1 FLOAT CHARGING AND BATTERY LIFE This is a charge given at a voltage higher then Most stationa ry batterie s are continuously con- the nominal float charge for a definite number of j nected to control circuits whien must be energized hours depending upon the value of the charge i at all times.This is accomplished by connecting the voltage. lts purpose is to compe nsate for any irregu-battery in parallel with a continuously operating larities that mav have occurred among cells in the charger and the desired load circuits. The cha rger is battery from causes such as a low float voltage for a then adjusted to a voltage which will enable the prolonged period of time due to faulty adjustment of battery to obtain just enough current to keep it fully the charger, or for a panel voltmeter which is charged. Under certain conditions, such as with improperly calibrated on the high side. It is also lead antimony batteries and lead calcium batteries usefulin restoring the battery to a full charge in a that are floated below recommended voltages, per- minimum time af ter an emergency discharge.(See iodic equalizing charges may be necessary. The Tables I and ll for equalize voltages.)

charger also furnishes current for the connected NOTE: Minimum acceptable voltage is the load. This is called float operation. It assures a f ully point at which plans should be made to provide ,

charged battery for any emergency service. Maxi- an equalizing charge.it does not imply that the l mum battery life is obtained in full float service, battery is malfunctioning or that it will not l If occasional discharges are experienced, battery provide power if called upon. Some equipment  ;

lif e will decrease in proportion to the f requency.and may not have equalizing potentials available.  ;

depth of these discharges. In such cases a single cell charger with com- l plete AC line isolation may be paralleled across In general It is customary that a stationary the affected cell while still a part of the overall 1

j battery will not experience any more than 200 discharge cycles evenly distributed throughout its battery to provide an over voltage to that cell.

usefullife. Frequent or greater depths of discharge Use the equalize voltage setting as shown in can shorten service life to 10 years or even less Tables I and 11. Do not be alarmed if such even with proper maintenance and operating condi-charging must continue for several weeks.

tions. Use Table I and Table !! to set float potentials, particularly in consideration that the currents s while adjusting to the higher float value when more actually passing through the cells are very frequent discharges are anticloated. For example, smaR ConsWt yow CE Sales /SeMee agent batteries f or photovoltaic service should be charged w is a o answer yow speck questions, at the maximum allowable potential " "'""** 0""

TABLEI 6.3 VOLTMETER CAllBRATION Panelvoltmeters used for float charging circuits LEAD ANTIMONY CELLS should be kept in accurate G!;bration by checking CHARGE VOLTAGE PER CELL (VPC) with a known standard at least every twelve months.

INITIAL F T EQUALIZE VPC HOURS VPC VPC minals and Compare this reading with the panel meter to eliminate line drop. Battery voltage should 2.39 do 2.15 to 2,17 2.33 always be measured with modern digital voltmeters 2.36 60 for 8 to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of at least 3% digit display arid .25% accuracy.(See 2.33 110 Tables I and 11 for float voltages.) This type of 2.30 168 Instrumentation is particularly usolul in recording 2 24 210 individual cell potentials.

If lead calcium the following table applies: 6.4 LEAD ANTIMONY BATTERIES TABLE ll Lead antimony batteries require an equalizing charge about every three months to one month as LEAD-CALCIUM CELLS the batterie a change electrochemically f rom new to CHARGE VOLTAGE PER CELL (VPC) old, respectively.

FLO AT VPC INITI AL/ EQU AllZ E (VPC)

SP. GR.

6.5 LEAD CALClUM BATTERIES MIN. ACC E PT-OF CELLS MIN. NOMINAL A8LE VPC NOM. VPC Usually lead calcium batteries do not need 1.170

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2.14 2.17 2.22 2'10 2292.34 ed voltage as indicated in Table 11. However, lead-1.210 2.17 2.20 2.25 2.13 2.33 2.38 calcium batteries which operate at the minimum 1.225 2.18 2.22 2.27 2.1 $ 2.36 2.40 float value should be given an equalizing charge 1 250 2.20 2.25 2.30 2.18 2.38 2.43 whenever the lowest cell in the string drops more 1.275 2.23 2.29 2.34 2.20 2.40 2.46 1.300 2.27 2.33 2.38 2.23 2.45 2.50 18 W

prJ74 & 246 1

than 0.04 volts below minimum float voltage or to the minimum acceptable voltage in Table 11. 6.10 CLEANING - DO'S AND DON'TS Wipe the outside cf the cells as necessary with a water-moistened cloth to remove dust and ordinary l 6 6 BATTERIES FOR PHOTOVOLTAIC SERVICE dirt. lf electrolyte is spilled on the covers, neutralize it Batteries for photovoltaic service have a less with a cloth moistened with a solution of baking soda defined discharge / recharge regime and as such and water mixed in the proportion of one pound of

' must be observed after the average full charge soda to one gallon of water. When fizzing stops 30 state. If it is determined that a cell (s) have fallen fresh soda solution is applied, wipe with a water-more than 0.04 volts below normal float it may be moistened cloth to remove all traces of soda.

necessary to add additional solar panels or reduce Never use solvents, detergents orothercleaning  !

the load dernand. Check the solar panel for dirt compounds or oils, waxes or polishes on the plastic l accumulation or possible malfunction of pan?l or containers or covers since such materials may attack l controls. Ecualize charge from auxiliary equipment the plastic and cause it to craze or crack. Aiwe.ys keep is shvays a good solution if the equipment is avail- the connectors and posts corrosion free and coated able. Charge at the highest equalize potential fc und w th NO OX lO grease or corrosion resistant oil. The l in Table 11. covers and container *, should be clean and dry at all times.

6.7 ENGidE STARTING BATTERIES .

Certain C&D stationary batteries (MHCSD, etc.) C&D is presently supplying some stationary bat-are used in engine cranking power forlarge diesel tenes encased in clear polycart>onate plastic con-powered generators. The frequency of such discharg* tainers which can be identified by their appearance.

es and the depth is unpredictable, but the service (Their color is generally water white, although when must be regarded as heavy cycle service. As such viewed from an angle they have a bluish tint.) They ,

cell (s) will become out of line with normal float are extremely acid resistant, free from Intemal potential.The solution is to provide equalize charge stresses and have superior impact resistance.

at tne highest practical potential shown in Tables l CAUTION and 11.

CLEANING POLYCARBONATE JARS l 6.8 RECHARGE FOLLOWING EMERGENCY Clean orwash the polycarbonate containers OtSCHARGE at wder onh.

-- 4 Batteries lef t in the discharged sta te for periods " ** * * * ** "

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of time iaysulfate,orinthecaseof severedischarge, a n a nah ng abhr hydrate which is a state of complete failure. Hydra- use ammonia, soda ash, sodium hydroxide tion will t;e discussed in Section 10.S. orany strong alkalles, if alkallee are inadver- <

Both lead antimony and lead calcium batteries tently spilled on the containers, they should should be recharged as quickly as practical following be immediately washed off with water. 4 an emergency discharge. Where conditions permit, 6.11 CHECKING CONNECTIONS this can be done by raising the bus voltage to the NOTE: Many protective coatings designed to maximum allowed by the other circuit components inhibit corrosion of connecting terminals con-but not to exceed the values listed in Table s I and ll. tain chlonnated solvents which may bo harmful if charging at equalize voltage is impractical, re-

harge at float voltage. to the battery and particularly to the cover and plastic container for the cells. C&D Batteries recerornends the exclusive use of NO OX lO 6.9 WATER ADDITIONS grease or special corrosion resistant oil sup-in addition to normal evaporation, as batteries plied for the battery by CAD Batteries and are floated and charged, a small quantity of the available upon order for subsequent scheduled maintenance, water in the electrolyte is broken down into hydrogen and oxygen by the charging current. These gases Maintenance of connections is one of the most I are dissipated through the flame arrestor. As this important tasks for which the useris responsible. A takes place, the electrolyte levolgradually drops so loose or corroded connection can often oevelop a that from time to time it is necessary to replace this high resistance circuit. If a high current load is loss with water. Keep the electrolyte level between suddenly required from the battery an extremely the high and low levellines by adding approved or large amount of power can be dissipated at the distilled water as required. Refer to Section 4.9

connection,of ten leading to a melt down of the post

Adjusting Electrolyte Level and Watering of Sat- and possibleignitionof thecoverof thecellorother tery" to better understand the rate of waterloss and neighboring parts. Only you the user can inspect the quality of water which must be used for water and maintain connection integrity. lt is recommend-additions.

ed that all electrical connections associated with Along with cell voltage, specific gravity records the battery be inspected routinely at least four time s yearly and retorqued a s required to the torque mustinclude the amount and date of water additions.

values given in Table I of Section 4.6 titled "Subse- ,

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/mi HB-zK quent Retorquing". Remember connections tend to work loose and lead has a physical property of "cold cating remedialaction when necessary. At periodic flow". Do not overtorque, however, since this will intervals, which will necessarily vary with location stress and distort the post and cause accelerated and system routines, the following information cold flow of the lead post. should be recorded and reported to the supervising authority: date; date and description of last equal-Izing charge (if lead antimony); battery floating volt-CAUTION age; pilot cell hydrometer reading; pilot cell temper-ature; and quantity of water added.

Maintenance of connections, both tight.

ness and cleanliness, is essential to safe Periodically, read and record Individual cell operation of a battery. This is not the re- specific gravities and voltages and note any unusual-conditions.

sponsibility of C&D Batteries but that of the user, as an integral part of battery mainton- if irregularities occur, consult the nearest C&D ance, Sales / Service agent and send a copy of the latest i report c/o C& D Power Systems, Technical Services '

S.12 RECORDS Department. 3043 Walton Road, Plymouth Meeting, A record of the battery operation is invaluable PA 19462. Ind!cate whom you have called upon i (see Fig. 21 as sample) in helping to determine from the C&D Sales / Service directory and when he l causes for associated equipment difficulties; for visited your facility for inspection. '

checking on maintenance procedures; and forindi- l I

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r JM/9% MS SECTION XU CmENSED INSTRUCTIONS FOR INSTALLATION AMD GPIRATIOR CAUTION: negative throughout. Connecilons between cells must be WET B ATTERIES must be placed on charge within three clean, dry, free of acid and coated with NO OX lO grease or months if lead antimony or six months if lead calcium corrosion resistant oil before bolting together. See Section from time of shipment from factory. IV,"trntallation of Cells", of Section 12 800.

DRY CHARGED BATTERIES must be propert" activated 3. CONNECTING BATTERY TO CHARGER Only direct and charged within 12 months. See RS 758 or Section current (DCl is used for charging. Connect battery positive Vill in 12 800, terminal to charger positive terminaf and battery negative terminal to charger negative terminal.

WARNING:

Electrolyte la en acid and can cause severe burns. Always 4. WATERING Add approved or distilled water after charg-wear protective clothing such as a rubber apron. safety ing and as required to keep electrolyte level between high goggles and rubber gloves when working around batteries. and low level lines on container.

1. RECEIVING If packing rnatorial shows evidence of 5. CLEANING Keep outside of cells clean and dry by physical damage or spillage of electrolyte make notation on wiping with a water damp cloth as required and dry. Neutralize bdi of lading before signing. Check electrolyte level in each any acid on covers or connectors with a Cloth moistened with cent.it should be between low and high levellines.lf more than a solution of baking soda and water.then wipe off alltraces of

%" of plate surf ace has been exposed to air. the cell has soda. NEVER USE ANY SOLVENTS, CLEANING COM-suffered cermanent damage and should ee replaced. POUNDS, OILS, WAXES OR POLISHES ON PLASTIC CONTAINERS OR COVERS SINCE SUCH MATERIALS

2. INSTALLATION Locate battery in a cool, cfean, dry MAY ATTACK THE. PLASTIC AND CAUSE IT TO CRAZE place so no cells are affected by radiators, heaters, or pipes.

OR CRACK. 00 NOT USE ANTI CORROSION AEROSOL Arrange ceits on h ;k so they can be connected positive to SPRAYS ON CONNECTIONS.

PURPOSE AND METHODS OF CHARGING (REFER TO TABLES I & 11)

INITI AL CH ARGE - (Use recommended float voltage value unless other circuit components make it necessary to use the minimum float A. Lead Antimony Type) (1.210 nominal specific gravity) ,

voltage values.) Check panel voltmeter against a known Give initial charge not later than three months after standard annually and calibrate if necessary.

battery has been shipped and at tighe st voltage permitted [

by connected load. Table I shows various suggested EQUAllZING CHARGES Compensate forirregulantiesin ' ' i voltages and corresponding time. floating. Equalize charges are also reouired if cells reach critical voltages listed in Table ll. Raise bus voltage to values O. Lead Calcium Types (Check nominal specific gravity shown in Tabin I and it. Continue charge at these elevated 1 shown on nameplate on top of cetis before proceeding.)

values untillowest cel reads within o.05 volts of the average Charge st hig h e st voltage per celi cermitted by connecteo of the cells in the lead calcium battery. Lead antimony cells load (equaure value if oossible) until voltage of lowest ce(I are equalized regularly at intervals of one to three months stops nsing and then continue for an additional 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

and are charged at eoualize potential for eight to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

if lead-calcium cells are to be floated at the recommended voltage they will automatically receive their initial charge FINISH RATES Normal finish rates are SA/100 AH of the at this voltage, providing they have not been on open eight hour capacity or 6A/100 AH of the three hour capacity. ,

circuit for more than six months, if on open circuit longer Finish rate currents are utilized in constant current charging L than six months they should be given an extended equal- for initial charging of dry charged cells and special remedial izing charge. Contact yourlocal C&D representatrve or the charging technique s. Float and equalize currents are consid-C& O Technical Se rvice s Copartm ent f or more inf ormation, etably lower current values.

FLOAT CHARGING Float batteries continuously after the initial charge from a voltage regulated OC supply bus at the values in Tables I and 11' TABLE 11 TABLEI LEAD CALCIUM CELLS LEAD ANTIMONY CELLS CHARGE VOLTAGE PER CELL (VPC) ,

FLO AT V PC IINITIAIJEQUALIZ E (VPC) .i CHARGE VOLTA 05 PER CELL (VPC) l (1.210 Specific Gravity) SP.GR. iMIN. ACCEPT-]

INITIAL  ! FLOAT EQUALIZE OF CELLS l MIN. NOMINALI ABLE VPC ( N OM. VPC iVPC ' HOURS i VPC VPC 1.170 2.14 2.17 2.22 2.10 2.29 2.34

! 2.39 ! 40 2.15 to 2.17 2.33 1.210 2.17 2.20 2.25 2.13 2.33 2.38 l 2.36 ! 60 for 8 to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 1.225 2.18 2.22 2.27 2.15 2.36 2.40

' 2.33 l 110 1.250 2.20 2.25 2.30 2.18 2.38 2.43 I2.30 l 168 1.275 2.23 2292.34 2.20 2.40 2.46 2 24 '

210 1.300 2.27 2.33 2.38 2.23 2.45 2.50 36

/M5948460 SECTION VI OPERATION <

6.0 OPERATION 6.2 EQUALIZING CHARGE

)

6.1 FLOAT CHARGING AND BATTERY LIFE This is a charge given at a voltage higher than Most stationary batteries are continuously con, the nominal float charge for a definite number of nected to control circuits which must be energized hours depending upon the value of the charge at all times This is accomplished by connecting the voltage. its purpose is to compensate foranyirregu-battery in parallel with a continuously operating larities that may have occurred among cells in the charger and the desired load circuits. The charger is battery from causes such as a low float voltage for a then adjusted tr., a voltage which will enable the prolonged period of time des to faulty adjustment of battery to obtain just enough current to keep it fully the charger, or for a panel voltmeter which is charged. Under certain conditiens, such as with improperly calibrated on the high side. It is also lead antimony batteries and lead-calcium batteries usefulin restoring the battery to a full charge in a that are floated below recommended voltages, per- minimum time after an emergency discharge. (See iodic equalizing charges may be necessary. The Tables I and 11 for equalize voltages.)

charger also furnishes current for the connected NOTE: Minimum acceptable voltage is the load. This is called float operation. It assures a fully I point at which plans should be made to provide charged battery for any emergency service. Maxi- b an equalizing charge. it does not imply that the P mum battery life is obtained in f ull float service, battery is malfunctioning or that it will not if occasional discharges are experienced, battery provide powerif called upon.Some equipment h

life will decrease in proportion to the f requency and may not have equalizing potentials available.

depth of these discharges. In such cases a single cell charger with com-In general it is customary that a stationary plete AC line lsolation may be paralleled acrosa I battery will not experience any more than 200 the affected cell while still a part of the overall discharge cycles evenly distributed throughout its battery to provide an over voltage to that cell.

usefullife. Frequent or greater depths of discharge Use the equalize voltage setting as shown in can shorten service life to 10 years or even less Tables I and 11. Do not be alarmed if such even with proper maintenance and operating condi- charging must continue for several weeks, / ,

p tions. Use Ta ble I and Table ll to set float potentials, while adjusting to the higher float value when more particularly in consideration that the currents actually passing through the cells are very Q pl i

frequent discharges are anticipated. For example, small. Consult your C&D Sales / Service agent 1

batteries for photovoltaic service should be chcrged w is a to answeOm spdc quesdons.  !

at the maximum allowable potential. or obtain the necessary information.

TABLEl 6.3 VOLTMETER CAllBRATION LEAD ANTIMONY CELLS Panel voltmeters used for floa t cha rging circ uits CHARGE VOLTAGE PER CELL (VPC) should be kept in accurate calibr&tior: by checking (1.210 Specific GravtM ' with a known standard at least every twelve months.

INITIAL FLOAT EQUALIZE Always measure battery voltage at the battery ter-  ;

VPC HOURS VPC VPC minals and compare this reading with the panel i 2.39 40 2.15 to 2.17 meter to eliminate line drop. Battery voltage should 2.33  !

2.36 60 always be measured with modern digital voltmeters for 8 to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of atleast3% digitdisplayand.25% accuracy.(See 2.33 110 l 2.30 168 Tables I arid 11 for float voltage:J This type of 2.24 instrumentation la particularly useful in recording 210 individual cell potentials. '

l If lead-calcium the following table applies: 6.4 LEAD ANTIMONY BATTERIES TABLE 11 Lead entimony t atteries require an equalizing LEAD-CALCIUM CELLS charge about every three months to one month as the batteries changs electrochemically from new to CHARGE VOLTAGE PER CELL (VPC) old, respectively.

FLOAT VPC INITIAL /EQU ALIZE (VPC)

SP.GR. MIN. ACC E PT- 6.5 LEAD CALCIUM BATTERIES OF CELLS MIN. NOMINAL ASLE VPC NOM. VPC Usually lead calcium batteries do not need 1.170 2.14 2.17 2.22 2.10 equalizing charges when floated at the recommend-2.29-2.34 -

1.210 2.17 2.20 2.25 2.13 2.33 2.38 ed voltage as Indicated in Table ll. However, lead-  ?

1.22 $ 2.18 2.22 2.27 2.1 $ 2.36 2.40 calcium batteries which operate at the minimum  %.

1.250 2.20 2252.30 2.18 2.38 2.43 float value should be given an equalizing charge 1.275 2.23 2.29 2.34 2.20 whenever the lowest cellin the string drops more 2.40 2.46 1.300 2.27 2.33 2.38 2.23 18 2.45 2.50

. .\

.*****~ww. ,4,,, . - , . - - , - - , , _ . - -

. /MMfB -360 than 0.04 volts below minimum float tfoltage or to the minimum acceptable voltage in Tablell. Od o . CLEADMfeGF Dc!S-^W'**TS-e-] '

Epe the outside of the cells as necessarywith a water moistened cloth to remove dust and ordinary i

6.6 BATTERIES FOR PHOTOVOLTAIC SERVICE dirt. lf electrolyte is spilled M the covers, neutralize it Batteries for photovoltaic service have a less with a cloth moistened with a solution of baking soda defined discharge / recharge regime and as such and water mixed in the proportion of one pound of must be observed after the average full charge soda to one gallon of water. When fizzing stops as state. If it is determined that a cell (s) have fallen fresh soda solution is applied, wipe with a water- I more than 0.04 volts below normal float it may be moistened cloth to remove all traces of soda.

necessary to add additional solar panels or reduce the load demand. Check the solar panel for dirt ,

accumulation or possible malfunction of panel or i controls. Equalize charge from auxiliary equipment the plastic and ca use it to craze or crack. Always keep is always a good soluticn if the equipment is avail- ,

g able. Charge at th e highest ecualize potential found g l

in Table 11.

g l times.

6.7 ENGINE STARTING 8ATTERIES Certain cad stationary batteries (MHCSD, etc.) C&D is presently supplying some stationary bat- I are used in engine cranking power for large diesel teries encased in clear polycarbonate plastic con-l powered generators. The frequency of such discharg- tainers which can be identified by their appearance.

es and the depth is unpredictable, but the service (Their color is generally water-white, although when must be regarded as heavy cycle service. As such viewed from an angle they have a bluish tint.) They cell (s) will become out of line with normal float are extremely acid resistant, free from intemal potential. The solution is to provide equalize chargo stresses and have superior impact resistance.

i at the highest practical potential shown in Tables I I

andit.

TM CLEANING POLYCARBONATE JARS  !

6.8 RECHARGE FOLLOWING EMERGENCY Clean or wash the polycarbonate containers OlSCHARGE ear water onh,

'O/ Batteries left in the discharged slate for periods Neutralize acid spills with a solution of of time maysuttate,orin thecaseof severe discharge, so um Mcaenate Mmg sodab Never

~ hydrate which is a state of complete failure. Hydra- use ammonia, soda ash, sodium hydroxide tion will be discussed in Section 10.5. orany strong alkalles. lf alkalles are inadver-  ;

{ Bot.h lead-antimony and lead-calcium batteries tently spilled on the containers, they should

, should be recharged as quickly as practical following be immediately washed off with water.

an emergency discharge. Where conditions permit.

this can be done by raising the bus voltage to the

'g maximum allowed by the other circuit components NOTE: Many protective coatings designed to

! inhibit corrosion of connecting terminals con-i but not to exceed the values listed in Tables I and ti. tain chlorinated r.olvents which may be harmful If charging at equalize voltage is impractical, re-

} charge at float voltage, to the battery and particularly to the cover and plastic container for the cella. CAD Batteries -

! recommends the exclusive use of NO-OX lO 6.9 WATEFt ADDITIONS - grease or special corrosion resistant oil sup-in add'ilon to normal evaporation, as batteries plied for the battery by C&D Batteries and are floated and charged, a small quantity of the available upon orderfor subsequent scheduled maintenance.

waterin the electrolyte is broken down into hydrogen and oxygen by the charging current. These gases Maintenance of connectionsis one of the most are dissipated through the flame arrestor. As this important tasks for which the useris responsible. A takes place, the electrolyte level gradually drops so loose or corroded connection can of ten develop a that from time to time it is necessary to replace this high resistance circuit. If a high current load is loss with water. Keep the electrolyte level between suddenly required from the battery an extremely the high and low levellines by adding approved or large amount of power can be dissipated at the distilled water as required. Refer to Section 4.9: connection,oftenleadingtoamelt downof thepost "Adjusting Electrolyte Level and Watering of Bat- and possibleignitionof thecoverof thecellorother tery" to bettsr understand the rate of waterloss and ' neighboring parts. Only you the user can inspect the quality of water which must be used for water and maintain connection integrity. It is recommend-

} additions.

' ed that all electrical connections associated with Along with cell voltage, specific gravity records the battery be inspected routinety at least four time s yearly and retorqued as required to the torque must include the amount and date of water additions.

values given in Table i of Section 4.6 titled "Subse-19

, , , -- ,, , - - . --a - - - - -

.. /Mf 948-Sao _

t quent Retorquing". Remember connections tend to cating remedial action wh6n necessary. At periodic I work loose and lead has a physical property of "cold intervals, which will necesaarily vary with location flow". Do not overtorque, however, since this will stress and distort the post and cause accelerated and system routines, the following information ,

f.

cold flow of the lead post. should be recorded and reported to the supervising -

l authority date; date and description of last equal- -

{

izing charge (iflead antimony); battery floating volt-ag e; pilot cell hydrome ter reading; pilot cell tem pe r-CAUTION ature; and quantity of water added.

s I

Maintenance of connections, both tight. Periodically, read and record individual cell ness and cleanliness, is essential to safe specific gravities and voltages and note any unusual operation of a battery. This is not the re- conditions. ')

sponsibilityof C&D Batterfes but that of the ,

user, as an integral part of battery mainton- if irregularities occur, consult the nearest C&D ance. Sales / Service agent and send a copy of the latest report c/o Technical Services Department, Station-6.12 RECORDS ary Batteries, C&D Batteries. 3043 Walton Road, A record of the battery operation is invaluable Plymouth Meeting, Pennsylvania 19462. Indicate (see Fig. 21 as sample) in helping to determine whom you have called upon from the C&D Sales / :l causes for associated equipment difficulties; for Service directory and when he visited your facility j!

checking on maintenance procedures; and forindi- for inspection.

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• i 80

=i b SECTION Xil CONDENSED INSTRUCTIONS FC7R INSTALLATION AND OPERATIONX CAUTION:

negative throughout. Connections between cells must be WET BATTERIES must be placed on charge within three months if lead antimony or six months if lead calcium citth dry, free of acid and coated with NO<)X lO grease or from time of shipment from factory. corrosion resistant oil before botting together. See Section IV. "Installation of Cells", of Section 12 800.

DRY CHARGED BATTERIES must be property activated and charged within 12 months. See RS 758 or Coction 3. CONNECTING SATTERY TO CHARGER Only direct Villin 12 800, current (DC) is used for charging. Connect battery posttive terminal to charger positive terminal and battery negative WARNING: terminal to charger negat:ye terminal.

Electrolyte is an acid ar;d can cause severe burns. Always

4. WATERING Add approved ordistilled waterattercharg-wear protective clothing such as a rubber apron, safety goggles a nd rubbergloves when working around batteries, ing and as required to keep electrolyte level between high and fow level lines on vontainer.

1. RECEIVING If packing material shows evidence of physical damage or spillage of electrolyte make notation on 5. CLEANING Keep outside of cells clean and dry by wiping with a water damp cloth as required and dry. Neutralize bill of lading before signing. Check electrolyte level in each any acid on covers or connectors with a cloth moestened with cell. it should be between low and high levet lines. lf more than a solution of baking soda and water.then wipe off alltraces of

%" of plate surf ace has been exposed to air, the cell has suff ered permanent damage and should be replaced. soda. NEVER USE ANY SOLVENTS. CLEANING COM.

POUNDS, OlLS, WAXES Olli POLISHES ON PLASTIC

2. INSTALLATION Locate battery in a cool, clean dry CONTAINERS OR COVERS SINCE SUCH MATERIALS place to no cells are affected by radiators. heaters.or pipes. MAY ATTACK THE PLASTIC AND CAUSE IT TO CRAZE Arrange cells on rack so they can be connected positive to OR CRACK. DO NOT USE ANTI CORROSION AEROSOL SPRAYS ON CONNECDONS.

INITIAL CHARGE PURPOSE AND METHODS OF CHARGING (KEFER TO TABLES I & 11)

(Use recommended float voMaga value unless other circuit

• A. Leao Antimony Types (1.210 nominal specific gravity) . components make it necessary to use the minimum float Give initial charge not later than three months after voltage valuet) Check panel voltmeter against a known battery has been shipped and at highest voltage permitted ,

f standard annually and calibrate tf necessary. I by connected load. Table i shows various suggested voltages and corresponding time. EOUALIZING CHARGES Compensate forirregulanties in floating. Equalize charges are also required if cells reach B. Lead-Calcium Types (Check nominal specific gravity critical voltages listed in Table tt. Raise bus vottage to values shown on nameplate on top of cells before proceeding) shown in Tables I artill Contines charge at these elevated Charge a t high est voltage per cell pe rmitte d by con nected &

values untillowest cell reeds within 0.05 volts of the average load teaualize value if possible) untilvoltage of lowest cell of the cells in the lead calcium battery. Lead antimony cells i

stops rising and then continue for an additional 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. are equalized regularty at intervals of one to three months If lead calcium cells are to be floa ted a t the recommendedand are charped at equalize potential for e>gnt to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

voltage they will automatically receive their initial charge at this voltage, providing they have not been on open FINISH RATES Normal finish rates are 5A/100 AH of the circuit for more than six months, if on ocen circuit longer eight hour capacity or 6A/100 AH of the three hour capacity.

than six months they should be given an extended equal- Finish rate currents are utilized in constant current charging izing charge Contact yourlocalC&D representatrvo orthe for initial charging of dry charged cells and special remedial CA D Technical Services Depa rtment f or more mf ormation. charging techniques. Flost and eQualiza currents are consid-erably lower current values.

FLOAT CH ARGING Float battenes continuously after the initial charge from a voltage-regulated DC suppiy bus at the values in Tables I and il TABLE 11 TABLEI LEAD-CALCIUM CELLS LEAD-ANTIMONY CELLS CHARGE VOLTAGE PER CELL (VPC)

CHARGE VOLTAGE PER CELL (VPC) FLOAT VPC INITIAL /EQUAllZE (VPC) 0 11.210 Specific Gravity) SP. GM.

EINITIAL FLOAT EQUALIZE MIN.ACC EPT-OF CELLS MIN. NOMINAL ASLE VPC NOM. VPC s

VPC jHOURS VPC VPC 1 l.170 2.14 2.17 2.22 2.10 2.29 2.34 2.39 40 2.15 to 2.17 2.33 1.210 2.17 2 36 60 2.20-2.25 2.13 2.33 2.34 2.33 for 8 to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 1.22S 2.18 2222.27 2.15 2.36 2.40

'm 110 1.250 2.20 2.25'2.30 2.18 2 30 168 2.38 2.43 1.275 2.23 2.29 2.34 2.20

2 24 210 2.40-2.48 1.300 2.27 2.33 2.38 2.23 2.45 2.50 36

_ _ - _ --