Technical manual section 04

BCI Battery Technical Manual BCIS-04 REV DEC02 Issued 1993-01 Current Revision: 2002-12 Approval Submission: 2001-11 BCI RECOMMENDED STORAGE BATTERY SPECIFICATIONS STARTING, LIGHTING AND IGNITION TYPES SCOPE : 1.1 Purpose : These procedures are for testing lead-acid storage batteries intended for starting, lighting and ignition service in passenger cars, commercial vehicles and off-highway vehicles which are equipped with voltage regulated charging systems 1.2 Field of Application : The purpose of testing may be to establish and declare performance ratings which allow match of product to application; to verify declared performance; to measure aspects of quality control; to compare products different in design or construction; and/or to evaluate developments in material, design and manufacturing methods These procedures focus on flooded lead acid batteries Modifications are noted for testing valve regulated lead acid (VRLA) batteries of either gelled or absorbed glass design 1.3 Product Classification : Whatever the purpose, the procedures provide standard methods of measuring recognized battery performance criteria However, the interpretation of results must take into account test sample size and be carried out using accepted norms of statistical practice 1.3.1 Form : Though the procedures may be used to assess performance loss due to the service or storage, it must be recognized that tests, if conducted to verify achievement of declared performance ratings, must be carried out on products which were new at the start of any test sequence Batteries should be unused and undamaged with no previous performance testing, and be no less than seven and no more than sixty days from date of manufacture BCIS-04 Rev DEC02 REFERENCES : 2.1 Definitions 2.1.1 RESERVE CAPACITY RATING is expressed as the number of minutes to reach 1.75 V/cell when a new fully charged battery at 80°F (26.7°C) is continuously discharged at 25 A 2.1.2 The COLD CRANKING PERFORMANCE (0°F) RATING is the discharge load in amperes which a new fully charged battery at 0°F (-17.8°C) can continuously deliver for 30 seconds and maintain a terminal voltage equal to or higher than 1.20 volts per cell 2.1.3 This VIBRATION TEST is to determine the ability of a battery to withstand G-levels similar to those developed in on-road applications of passenger car and light truck vehicles without suffering mechanical damage, loss of capacity, or loss of electrolyte For batteries designed for off- road applications, SAE J930 may apply BCIS-04 Rev DEC02 PRETEST CONDITIONING AND CHARGING: 3.1 Dry Charged or Similar Batteries Which Need Electrolyte to Activate: For the Cold Activation test, fill batteries in accordance with the specific test procedure Fill others, not to be subjected to the Cold Activation Test, according to the manufacturers' directions and then treat them as any other filled and charged battery in pretest conditioning 3.2 Filled and Charged Batteries, With Cell Access: Addition of water to replace that lost during a test sequence is permitted if recommended by the manufacturer No other adjustments to acid strength or electrolyte volume are allowed 3.3 Filled and Charged Batteries, Without Cell Access: In batteries, which operate with excess liquid electrolyte, provision to measure specific gravities and temperatures is to be made by carefully cutting holes through the cover in locations recommended by the manufacturer These holes must be capable of being closed to retain integrity of the venting system Batteries shall be tested with the electrolyte concentration as supplied by the manufacturer Adjustments to electrolyte strength or volume in such batteries are not permitted during preparation or testing 3.4 VRLA batteries: VRLA batteries have no provision for directly reading electrolyte specific gravities or temperatures For VRLA batteries, charging and testing temperatures must be carefully regulated The internal temperature of the battery will be considered to be equal to the temperature of the negative post, except in cases where the manufacturer has molded a deep pocket into the cover for the insertion of a temperature probe 3.5 Corrections to Specific Gravity and Voltage Readings for Temperature Changes: 3.5.1 Electrolyte Specific Gravitites: Specific gravity comparies the weight of a substance to the weight of an equal volume of pur 80°F (26.7°C) water Electrolyte specific gravities are specified at a standard temperature of 80°F (26.7°C) Specific gravity decreases as liquid temperature increases, and vice versa Test measurements made at other temperatures (T) must be corrected to the standard temperature using the following formula: 3.5.1.1 Fahrenheit Correction: Specific Gravity at 80°F = measured value + 0.0004 (T-80) 3.5.1.2 Celsius Correction: Specific Gravity at 26.7°C = measured value + 0.0007 (T-26.7) 3.5.2 On-charge terminal voltage for constant current charging : The on-charge terminal voltage for constant current charging is specified at a standard temperature of 80°F (26.7°C) It must be reduced with increased temperature and vice-versa, using the following formula: 3.5.2.1 Fahrenheit Correction: BCIS-04 Rev DEC02 Terminal Voltage at 80°F = reading – [No Cells x 0.0035 (T-80)] 3.5.2.2 Celsius Correction: Terminal Voltage at 26.7°C = reading – [No Cells x 0.0063 (T-26.7)] 3.5.3 Corrections must not be made to open-circuit voltage readings or to voltages measured during discharge 3.6 Charging Temperature: Charging must not be started if electrolyte temperature is below 60°F (15.6°C) During charge, the temperature must be maintained between 60°F (15.6°C) and 110°F (43.3°C) 3.7 Constant Current Charging : Prior to starting a constant current recharge, calculate the ratio of Cold Cranking rating (amperes, A) divided by Reserve Capacity rating (minutes) If this ratio is greater than or equal to 5.0, the constant current is to be set at a whole ampere value that lies between 0.5% and 0.75% of the Cold Cranking Performance (0°F) rating (in amperes) Otherwise, the constant current is to be set at a whole number ampere value between 0.75% and 1% of the Cold Cranking Performance (0°F) rating 3.7.1 The appropriate constant current must be continued until the criteria establishing full charge are achieved, for a predetermined time, or to a predetermined percentage of overcharge specified by the manufacturer 3.7.2 Batteries that are similar in design and that are discharged to the same extent may be series connected for recharge up to the voltage capacity of the charger unit 3.7.3 Full charge indications For a flooded battery, two basic criteria may be used to recognize when the battery is fully charged: 3.7.3.1 When the specific gravity of the electrolyte is constant within ± 0.002 over three consecutive one-hour intervals 3.7.3.2 When the on charge terminal voltage at the constant current does not change by more than 0.008 volts per cell per hour over three consecutive hourly intervals 3.7.3.3 The readings must be corrected to 80°F (26.7°C) to eliminate the effects of changing temperatures 3.7.3.4 The criterion of constant cell specific gravity readings can only be used in those batteries which incorporate liquid electrolyte and have provisions for cell access 3.7.4 When preparing and testing VRLA batteries follow the manufacturer's instructions to achieve and recognize a full charge VRLA batteries are generally not charged by constant current methods 3.8 Constant Voltage, Current Limited, Charging : Prior to starting constant voltage charging, the correct applied voltage for the battery must be known Applied voltages will need to be selected between 2.30 - 2.75 V/cell as battery types BCIS-04 Rev DEC02 and designs differ When the correct applied voltage is not known, testing laboratories should request information on voltage and charging times from the battery manufacturer 3.8.1 For constant voltage charging the charger output must be capable of at least 25 amperes per battery 3.8.2 Equalizing charge: An equalizing charge at the appropriate constant current rate is allowed, in conjunction with constant voltage charging, to promote electrolyte mixing and insure complete recharge The equalizing charge must not exceed hours and should be used cautiously to avoid excessive overcharge For VRLA batteries, no equalizing charge should be used unless specifically recommended by the manufacturer In such cases, the manufacturer’s instructions regarding current rate and charging time will be followed 3.8.3 The appropriate constant voltage must be continued until the criteria establishing full charge are achieved, for a predetermined time, or to a predetermined percentage of overcharge specified by the manufacturer 3.8.4 NOTE: The typical constant voltage time required following cold cranking is 12 hours and following reserve capacity is 24 hours plus any equalizing charge 3.8.5 Determining fully charged state in flooded batteries: For flooded batteries, two basic criteria may be used to recognize when the battery is fully charged: 3.8.5.1 When the specific gravity of the electrolyte is constant within ± 0.002 over three consecutive hourly intervals The criterion of constant cell specific gravity readings can only be used in flooded batteries that incorporate excess liquid electrolyte and have provision for cell access The specific gravity readings must corrected to 80°F (26.7°C) to eliminate the effects of changing temperature 3.8.5.2 When a constant current is observed over three consecutive one-hour intervals at a constant terminal voltage 3.8.6 When preparing and testing VRLA batteries that have gelled or absorbed electrolyte, follow the manufacturer's instructions to achieve and recognize full charge Batteries of the same design and that are discharged to approximately the same extent may be series connected for recharge within the voltage capability of the charger unit Batteries may also be parallel connected to a common voltage bus-bar system if the total current supply is adequate In either case of multiple unit charging, individual unit control to full charge is essential 3.8.7 Batteries of the same design that are discharged to the same extent may be series connected for recharge within the voltage capability of the charger unit Batteries may be parallel connected to a common voltage bus-bar system if the total current supply is adequate In either case of multiple unit charging, individual unit control to full charge is essential 3.9 Stand Time After Charging : At the end of a charge, batteries will be polarized above normal open circuit values and may be at a temperature which is higher than that specified for the subsequent test A period to allow depolarization and cooling will be necessary Minimum and maximum stand times between end of charge and beginning of test are detailed in each of the test procedures BCIS-04 Rev DEC02 TEST SEQUENCE : 4.1 Depending upon the objective of testing, because of the time needed to complete some tests, and their effect on on-going battery performance, testing sequences for discrete sets of batteries must be adopted according to the chart given below Repeat tests of Reserve Capacity and Cranking Performance are required only if the rated values were not achieved initially Table BCI Test Sequence Cold Activation (Dry Charged Only) (7) Preconditioning and Charging (3) Reserve Capacity (5.2) Charge Rate Acceptance (8) Cranking Performance (5.3) Repeat Reserve Capacity (5.2) Repeat Cranking Performance (5.2) Repeat Reserve Capacity Performance (5.3) Gassing (10) and/or Life Test Vibration Resistance (9) Rated Vibration Characterization Performance Resistance A B C X X X X X X X X X X X X X X X X X X X X BCIS-04 Rev DEC02 MEASUREMENTS OF BATTERY PERFORMANCE : 5.1 Battery Performance Characteristics To provide meaningful measurements of battery performance to the end user, battery engineers, supported by BCI (Battery Council International) and SAE (Society of Automotive Engineers), established two methods of expressing the performance characteristics of a battery capacity for engine cranking for starting and capacity for ignition, lighting and other accessories required in emergencies 5.2 Reserve Capacity Test Procedure: A battery may have to provide current for ignition and lighting in the event of failure in the vehicle's electricity generating system This test provides a measurement of its potential capacity to provide that power in terms of a comparative rating 5.2.1 When preparing and testing VRLA batteries that have gelled or absorbed electrolyte, follow the manufacturer's instructions to achieve and recognize full charge 5.2.2 Fully charge the battery according to the "Pretest Conditioning and Charging Procedure" and allow it to stand no less than hours or no more than 96 hours before the start of discharge 5.2.3 During the stand period, regulate battery temperature so that electrolyte temperature, measured above the plates in an intermediate cell, is stabilized at 80 ± 5°F (26.7 ± 2.8°C) before the start of the discharge The electrolyte temperature of a VRLA battery prior to the start of the discharge will be considered to be equal to the temperature of the negative post, except in cases where the manufacturer has molded a deep pocket into the cover for the insertion of a temperature probe 5.2.4 Discharge the battery at 25 ± 0.25 A During discharge, using any convenient method, maintain electrolyte temperatures within the range 75°F (23.9°C) to 90°F (32.2°C) Results will not be considered valid if electrolyte temperatures move outside this range before the end of the discharge 5.2.5 End the discharge when the voltage across the battery terminals has fallen to the equivalent of 1.75 V/cell, noting the discharge duration in minutes and the electrolyte temperature at the cut-off point 5.2.6 Correct the discharge duration for final temperatures different from 80°F (26.7°C) using the formulas, which follow and record the corrected time as the Reserve Capacity achieved 5.2.6.1 Fahrenheit Correction: Mc, = 5.2.6.2 Celsius Correction: Mc = Where: 5.3 Mr, [1 - 0.005 (T-80)] Mr, [1 - 0.009 (T-26.7)] Mc, = minutes corrected to 80°F (26.7°C) Mr, = minutes actually run T = end of discharge electrolyte temperature (°F) or (°C) Cranking Performance: BCIS-04 Rev DEC02 The primary function of a battery is the provision of power to crank the engine during starting This requires a short discharge at very high current and adequate voltage 5.3.1 WARNING - New, fully charged high-performance batteries can deliver significantly higher than rated discharge currents, particularly at elevated temperatures Therefore, care must be exercised during laboratory testing to avoid discharges above the rated current, temperature or duration, which could cause melting of terminal or internal connections that, may result in explosion of the battery Make sure that test batteries are properly filled with electrolyte Do not connect cables to the battery terminals using light spring clips, which inadequately conduct away generated heat Do not discharge batteries at currents greater than the manufacturers rating 5.3.2 Fully charge the battery according to the "Pretest Conditioning and Charging” procedure and allow it to stand at room temperature for to 96 hours before starting to cool it 5.3.3 Place the battery in a cold chamber held at a temperature between –2°F and 0°F (-19°C and -17.8°C) for the Cold Cranking Performance (0°F) test for at least 16 hours, until the electrolyte temperature measured above the plates in an intermediate cell, has stabilized at the test temperature of 0°F ± 1°F (-17.8°C ± 0.6°C) The electrolyte temperature of a VRLA battery prior to the start of the discharge will be considered to be equal to the temperature of the negative post, except in cases where the manufacturer has molded a deep pocket into the cover for the insertion of a temperature probe 5.3.4 With the battery still in the cold chamber, discharge the battery at the rating current The discharge current must be controlled within ± A 5.3.5 At 30 seconds after the start of the discharge, measure and record the terminal voltage of the battery under load This must not be less than the equivalent of 1.20 V/cell Iff the voltage falls below 1.20 V/cell before 30 seconds has elapsed, stop discharge Record time to 1.20 V/cell 5.3.6 NOTE: The test is not invalidated if the electrolyte temperature rises above the designated temperature during the 30 second period, as a result of the high discharge current BCIS-04 Rev DEC02 STANDARDS OF COMPLIANCE TO PERFORMANCE RATINGS : 6.1 When statistically evaluated in accordance with accepted sampling and testing procedures, 90% of all batteries should be expected to meet or exceed the Reserve Capacity Rating and 90% should be expected to meet or exceed the Cranking Performance Rating, based on each battery's best performance within a test sequence 6.2 Compliance to Reserve Capacity Rating and to Cranking Performance Rating should be evaluated separately 6.3 Batteries that fail to reach rated performance values during electrical tests should be checked for mechanical defects If any are defective, the test results for that battery should be disregarded in statistical analysis BCIS-04 Rev DEC02 COLD ACTIVATION PERFORMANCE : Even in a very well prepared dry-charged battery, the capacity in the plates cannot be 100% of their full capacity Also, the capacity retained over a period of time is affected by storage conditions, which are often outside the control of the manufacturer The Cold Activation Test provides a collective measure of effectiveness in processing, charge retention and the ability of a battery to activate when placed in service under cold weather conditions 7.1 Use electrolyte for filling which has a specific gravity of 1.265 ± 005 at 80°F (26.7°C) or as specified by the manufacturer 7.2 Place the battery and the electrolyte separately in a chamber cooled to 30°F ± 2°F (-1.1°C ± 1.1°C) for a minimum of 18 hours Verify that the electrolyte temperature has fallen to 30°F ± 2°F (-1.1°C ± 1.1°C) before using it to fill the battery 7.3 Remove the battery and electrolyte from the cold chamber Without delay fill each cell in the battery to the correct level 7.4 Allow the battery to stand for 20 minutes outside the cold chamber after complete filling of the last cell A temperature rise is to be expected and does not invalidate the test 7.5 Discharge the battery at a current rate equal to 75% of the Cold Cranking Performance Rating for the battery Measure and record the terminal voltage of the battery under load after 15 seconds of discharge 7.6 The battery is considered to meet minimum specification requirements if the terminal voltage measured at 15 seconds is at least equal to 1.20 V/cell 10 BCIS-04 Rev DEC02 RECHARGEABILITY AND CHARGE RATE ACCEPTANCE (SAE J537) : This test determines the battery capability to accept charge at low temperature when discharged, and to determine the rate at which the battery would accept the charge from a voltage regulated charging system, which has adequate current capacity 8.1 The charging equipment used in this test should be capable of a minimum current output in amperes equivalent to 50% of the rated reserve capacity value in minutes 8.2 Using the same battery discharged through reserve capacity test (5.2) or specifically discharged to 10.5 v at the reserve capacity rate per 5.2, place the battery in a cold chamber until the electrolyte temperature above the plates in an intermediate cell has stabilized at 0°C ± 1°C (32°F ± 2°F) 8.3 With the battery in a cold chamber, at 0°C ± 1°C (32°F ± 2°F) ambient, charge it at a constant potential equivalent to 14.40 ± 07 V After 10 minutes of charging, measure and record the current 8.4 Continue to charge for a total duration of 120 ± 0.5 minutes Discontinue the charging, remove the battery from cold chamber and raise the battery temperature until the electrolyte temperature above the plates in an intermediate cells has stabilized at 27°C ± 3°C (80°F± 5°F) 8.5 Discharge the battery at 25A ± 0.1A During discharge, using any convenient method, maintain electrolyte temperature within the range of 24°C (75°F) to 32°C (90°F) Results will not be considered valid if electrolyte temperature moves outside this range before the end of discharge 8.6 End the discharge when the voltage across the battery terminals has fallen to the equivalent of 10.50 ± 05V, noting the discharge duration in minutes and the electrolyte temperature at the cut-off point 8.7 Correct the discharge duration for final temperature different from 27°C (80°F) using the formulas from 5.2.6 8.8 Acceptance criteria for these tests 8.8.1 Charge rate acceptance : Current input after 10 ± 0.1 minutes of charging (8.4) shall be at least 3% of the battery’s cold cranking performance rating 8.8.2 Rechargeability: The discharge time in minutes as obtained after 120 minutes recharge (8.5) shall be at least the original reserve capacity value (5.2.6) 11 BCIS-04 Rev DEC02 VIBRATION RESISTANCE (SAE J537): 9.1 One or more fully charged batteries at 80°F ± 5°F (26.7°C ± 2.8°C) shall be placed on one of the vibration machines recommended for this test The batteries shall be symmetrically balanced on the LAB vibrator On the Ordnance vibrator, each battery shall be oriented symmetrically along the table centerline parallel to the shaft The battery plates shall be oriented parallel to the axis of the rotating shaft 9.2 The batteries shall be firmly held down by a top holddown frame bearing on the top four edges of the battery or by an optional top bar or bottom holddown The holddown nuts should be tightened to about 40 in/lb (4.5 Nm) for two bolt top holddowns The holddown torque shall be slightly less for top holddowns with more than two bolts Optional bottom holddowns can normally be tightened up firmly without concern for excess torque In no instance should bulging of the battery case exceed 0.05 in (1.3mm) per side due to excess holddown force 9.3 The electrolyte shall be at the level recommended by the manufacturer For VRLA batteries no electrolyte check or adjustment is necessary During vibration there must be no electrolyte loss 9.4 The batteries shall be vibrated for hours at an acceleration of 3.5 ± 0.2 G, at a frequency of 32 ± Hz Each four hours of vibration shall represent one unit of vibration 9.5 The total G-level shall be calculated from the vertical and two horizontal components by the formula below On the Ordnance table, the vertical component shall be determined near the high G level end of the battery (upward rotation side of shaft) On the LAB table, the vertical component shall be taken as the average of both ends of the battery Vertical G-level measurements "near battery ends" will be made on the battery centerline as close as possible to the battery's end wall for the particular measuring device used For both LAB and Ordnance tables, horizontal G-level measurement shall be made in (76 mm) from the corners on the vibration table sides The x- and y-horizontal components shall be taken as the average of th four ends of the two opposing table edges G-level may be determined by the use of accelerometer or independent excursion and frequency measurements as agreed between the supplier and customer G-force = 0.051f (x2 + y2 + z2 )½ Where: f is frequency in Hz x and y are horizontal excursions in inches z is vertical excursion in inches 9.6 All measurements shall be made with batteries in place on the vibration machine (See Figure 1) 9.7 After each unit of vibration, immediately discharge the battery at 80°F ± 5°F (27°C ± 3°C) at its specified Cranking Performance (0°F) rating If the 30 s voltage requirement is met, recharge according to methods given under Conditioning and repeat steps 9.4 and 9.7 until failure or a specified number of units have been successfully achieved 9.8 The battery will be rated at the number of units it can survive and meet the 30 s, 1.2 V/cell requirement 9.9 Test Equipment and Specifications - Vibration Machine - LAB vibration machines ARV- 30 x 40-400 or similar type (even number of counter rotating shafts, vertical vibration component only); or U.S Army Ordnance Battery Vibration Machine as shown on Drawing No D7070340 12 BCIS-04 Rev DEC02 10 GASSING RATE CHARACTERISTIC: 10.1 Charging at a constant voltage: A fully charged battery will accept a current which is characteristic of its design and construction In a flooded battery current is dissipated in electrolyzing water from the electrolyte into hydrogen and oxygen gases, which escape VRLA batteries recombine the oxygen and hydrogen to produce and preserve much of the water, producing heat instead These batteries contain a valve, or valves, which under normal use will control the release of gases In VRLA batteries, steady state current and gassing rate are completely unrelated The ratio of gassing rate to steady state current can be useful as a comparative measure of recombination efficiency There is no reservoir of electrolyte above the plates and the electrolyte is immobilized 10.2 Measurement of gas evolution rate vs Measurement of accepted current at a given voltage A measurement of gas evolution rate or the current accepted at a charging voltage typical of a vehicle electrical system, when related to the reservoir of electrolyte above the plates, provides a basis for comparing battery designs in respect to their ability to withstand service water losses Both measures are useful, but there is no applicable factor correlating them (1 Ah of overcharge – wasted electrolyzing water – should be expected to produce 627.2 ml of dry gas corrected to S.T.P., but in practice variation is often observed.) Both gas emission rates and currents are small values, which demand accurate measurement, avoidance of leakage losses, and good test technique 10.3 Procedure for Steady State Charging Current Measurement 10.3.1 Complete Cranking Performance and Reserve Capacity tests, then fully charge the battery as described in "Pretest Conditioning and Charging Procedure.” 10.3.2 Place the battery in an oven or water circulating bath held at a temperature of 125°F ± 2°F (51.7°C ± 1.1°C) 10.3.3 Apply a 14.1 ± 0.1 V charging voltage to a 12 V battery (7.05 V ± 0.05 V for volt batteries) for 16 to 18 hours 10.3.4 After this period of conditioning, commence regulation of temperature to 125°F ± 1°F (51.7°C ± 0.6°C) and of charging voltage measured across battery terminals to 14.1 ± 0.01 V (7.05 ± 0.005 V for volt batteries) 10.3.5 Continue charging under these conditions for additional hours while recording charging current at 15-minute intervals 10.3.6 If charging current has stabilized so that variations over three consecutive readings are 2% or less than the average of the three consecutive readings, record that average as the Steady State Charging Current in amperes Otherwise, continue charging until stability is achieved 10.4 Procedure for Gassing Rate Measurement: 10.4.1 Complete Cranking Performance and Reserve Capacity tests then fully charge the battery as described in “Pretest Conditioning and Charging Procedure.” 10.4.2 Verify the absence of intercell and perimeter cover-case leaks by applying an air pressure of one pound per square inch to each cell individually On accessible batteries pressure must 13 BCIS-04 Rev DEC02 be maintained for 15 seconds after disconnecting the source of pressurization Perimeter leak test only non-accessible batteries and batteries with manifold vented covers 10.4.3 Place the battery in an oven or water circulating bath held at a temperature of 125°F ± 2°F (51.7°C ± 1.1°C) and prepare it for gas collection and measurement through water displacement out of inverted burettes 10.4.4 If the design of the battery permits, collect the gas separately from at least three cells If not, collect the gas from the minimum number of cells that are common to one valve Collector burette volumes (in milliliters) must equal at least 300 times the Steady State Charging Current but need not be more than 100 ml The volume collected will be increased if the gas from more than one cell is collected Collecting tubes should be glass or metal as far as practical to reduce hydrogen escape by permeation Cells set up for gas collection require provision for venting The outlet of the tubes used for collection must be at the same level (elevation) as the surface of the water outside the burettes to prevent creating back pressure or a slight vacuum Also, when reading the volume collected, the burette must be raised or lowered so that the water level within the burette is equal to the water level outside the burette 10.4.5 Follow steps 10.3.2 through 10.3.6 above to bring the battery into Steady State Charging Current Condition with the evolved gases bubbling through the water used for displacement The temperature of this water should be maintained at room temperature 10.4.6 Start collection of gases and continue until volume collected in any burette reaches 100 ml but not longer than 30 minutes This time may need to be extended for VRLA batteries to get an accurate average gassing rate VRLA batteries have valves, which open and close Gassing (measured outside of the battery), if any, may not be steady The valve may occasionally open, release a burst of gas and then reseal 10.4.7 Record the individual volumes of gases collected the times of collection, the room temperature and the barometric pressure 10.4.8 Using data appropriate only to the cell, showing the greatest gas volume, calculate the dry volume of gas corrected to S.T.P (Standard Temperature and Pressure) Divide by time of collection to determine the characteristic Gassing Rate in ml/ minute/ cell NOTE: When gas from more than one cell must be collected, divide the volume by the number of cells to report the results as ml/ minute/ cell 14 BCIS-04 Rev DEC02 15 ...BCIS -04 Rev DEC02 REFERENCES : 2.1 Definitions 2.1.1 RESERVE CAPACITY RATING is expressed as the number... loss of electrolyte For batteries designed for off- road applications, SAE J930 may apply BCIS -04 Rev DEC02 PRETEST CONDITIONING AND CHARGING: 3.1 Dry Charged or Similar Batteries Which Need... following formula: 3.5.1.1 Fahrenheit Correction: Specific Gravity at 80°F = measured value + 0.0 004 (T-80) 3.5.1.2 Celsius Correction: Specific Gravity at 26.7°C = measured value + 0.0007 (T-26.7)