BCI Battery TechnicalManual REV BCIS-7 Issued Current Revision: DEC02 1993-05 2002-12 BCI SPECIFICATION FOR CYCLE LIFE TESTING OF BATTERIES FOR GOLF CARS TABLE OF CONTENTS Scope and Classification Cycle Life Test Conditions Test Procedure Performance BCIS-7 Rev DEC02 SCOPE AND CLASSIFICATION 1.1 The purpose of this specification is to provide a method for testing the life of golf car batteries in a charge-discharge cycling mode, which approximates the actual use of batteries in golfcar service The test procedure is designed to provide a standard basis for user comparison of products and for the evaluation of performance of production and development of batteries by battery manufacturers 1.2 Most golf cars operate with nominal 36-volt systems, and this is usually by series connection of six 6-volt monobloc BCI Group GC batteries For discharge, an average current of 75 amperes has been found to be realistic A 40 minute minimum discharge time corresponds to one round of golf per day at a typical golf course Almost all golf cars are charged with commercially available ferroresonant (tapering) chargers The BCI test operates with a 75ampere discharge simulated by an electronic load and specifies a tapering charging characteristic 1.3 The measure of performance of a set of batteries is the number of cycles (charge/discharge) until the discharge capacity at 75 amperes is less than 40 minutes Users which require a higher capacity cutoff should be able to get an appropriate value for cycle life from their battery manufacturer, since this information will be generated during each life test BCIS-7 Rev DEC02 CYCLE LIFE TEST CONDITIONS 2.1 Pretest Conditioning Procedures 2.1.1 All industry-sanctioned and approved standards are established on new (60 days or less since date of manufacture), fully charged batteries The following conditioning procedure has been established as a requirement prior to laboratory testing The batteries shall be charged at a rate in amperes equal to 3% of rated or expected six hour capacity in ampere hours, until all cells are gassing freely, and charge voltage and specific gravity of electrolyte are constant over three successive readings taken at one hour intervals The six hour rated capacity can be found by use of the BCIS-5, “BCI Specification for Rating and Testing Electric Vehicle and Cycling Batteries.” Alternately, a charging rate of to amperes for flat-pasted positive plate batteries and to amperes for tubular positive plate batteries may be used 2.2 Battery Ratings Measurements 2.2.1 It is permitted during life cycle testing to carry out discharges at different current rates to establish battery ratings Such discharges will count toward the overall cycle life, but they must be carried out in accordance with the conditions specified in the BCI TechnicalManual under the BCIS-5, “BCI specification for Rating and Testing Electric Vehicles and Cycling Batteries.” When carrying out such rating discharges, alterations to the water bath temperature and to the discharge-rest-charge time cycle are allowed, but only for the minimum period necessary to establish rating values Temperatures and cycle times must then be restored to the values stipulated below 2.3 Final Discharge Voltage 2.3.1 The final voltage, when discharge is terminated, shall be 1.75 times the number of cells for all tests of discharge at 75 amperes Since the test battery assembly consists of six 6-volt batteries in a series, or six 12-volt batteries in series/parallel, the final discharge voltage measured at the testing until terminals shall be 31.5 volts ± 1% 2.4 Temperature 2.4.1 Test batteries shall be maintained in a water bath at 32°C ± 3°C (nominal) 90°F ± 5°F)) The modules shall be allowed to soak in the constant temperature bath for a period of not less than 24 hours before any testing begins 2.5 Specific Gravity 2.5.1 Electrolyte specific gravity shall be as specified by the battery manufacturer for the fully charged battery 2.6 Readings 2.6.1 All voltage, specific gravity, and temperature readings shall be taken from the positive terminal cell to the negative terminal cell, recorded in a series and numbered If a series/parallel connection of 12-volt batteries is used instead of a series connection of 6-volt batteries, then each series path will be recorded and numbered separately The readings shall be taken no less than once a week during the test, at times when modules are at the same state of charge 2.7 Test Equipment 2.7.1 All equipment shall be clean, in good working order, and calibrated BCIS-7 Rev DEC02 2.7.1.1 Thermometers Shall be graduated so that each scale division will not represent more than 1°C (2°F) and shall have an accuracy of ± 1°C (+2°F) 2.7.1.2 Hydrometers Shall be graduated so that each scale division will not represent more than 0.005 units of specific gravity and shall be accurate to at least 0.005 units 2.7.1.3 Instrumentation Voltage and current readings shall be made with instruments capable of an accuracy of ± ampere and ± 1% of voltage reading or better Timers shall have an accuracy of 0.05% or better BCIS-7 Rev DEC02 TEST PROCEDURE 3.1 The battery pack may be preconditioned before life test Discharge tests to evaluate the battery ratings in the range between one and six hours of discharge time may be carried out if desired These discharges will be counted towards the overall cycle life of the battery pack 3.2 Discharge shall proceed at 75 ± 0.75 amperes until the battery pack voltage falls to 31.5 ± 0.315 volts, with this cutoff voltage as measured at the testing unit battery terminals After the cutoff voltage is reached, the battery pack is disconnected from the discharge load until the total time for discharge and open-circuit is 4.00 hours 3.3 The battery pack shall then be recharged for a period of 12 hours The charger shall have an initial charge current between 22 and 30 amperes and shall have voltage current characteristics of commercial ferroresonant full-wave, tapering-current chargers The voltages at the end of charge shall be in the range of 45.5 to 46.5 volts The selected end of charge voltage at the start of the test will not be deliberately altered during the course of the cycle life test 3.4 Immediately upon completion of the charge portion of the cycle, the battery pack shall start the next discharge, as defined in Subsection 3.2 The discharge/open-circuit/charge sequence shall be repeated every 16 hours Methods for counting elapsed cycles shall be at the discretion of the test operator 3.5 A battery on test shall be considered failed when it will not provide at least 1.75 volts per cell during 40 minutes of discharge at 75 ± 0.75 amperes A maximum of six cells (two 6-volt monoblocs or one 12-volt monobloc) may be replaced on test within the first 90 cycles if found to be failed by this criterion The replacement(s) may be new or previously cycled batteries at the recommendation of the battery manufacturer Beyond 90 cycles, no batteries may be replaced in the test battery pack 3.6 A battery pack shall be considered failed when it will not provide at least 40 minutes of discharge at 75 ± 0.75 amperes with a discharge voltage above cutoff (31.5 ± 0.315 volts) on two consecutive discharge cycles 3.7 Failure in a battery may be confirmed by readings of temperature, specific gravity, voltage as specified by the battery manufacturer 3.8 As an alternative to test of a 36-volt battery pack, one or two monobloc battery units may be tested with the discharge cutoff and failure correspondingly 1.75 ± 0.175 volts per cell The charger current-voltage characteristic must be identical to that for a commercial ferroresonant full-wave, tapering current charger, with end of charge voltage 2.526 to 2.583 volts per cell and an initial charge current of 22 to 30 amperes No failed battery modules may be replaced; failure of one module constitutes the end of the test BCIS-7 Rev DEC02 PERFORMANCE 4.1 Cycles of life to 40 minutes of discharge at 75 ±0.75 amperes shall be reported Since each discharge is to 100% of the effective depth of discharge, the capacity versus cycle life curve will be a smooth arc unless a catastrophic failure is encountered The end-of-life criterion of 40 minutes corresponds to one round of golf (18 holes) at a typical golf course ... life, but they must be carried out in accordance with the conditions specified in the BCI Technical Manual under the BCIS-5, “BCI specification for Rating and Testing Electric Vehicles and Cycling... charge portion of the cycle, the battery pack shall start the next discharge, as defined in Subsection 3.2 The discharge/open-circuit/charge sequence shall be repeated every 16 hours Methods