Technical manual section 08

Each battery shall be charged at a whole number ampere rate between 3% and 4% of the rated or expected minutes of discharge at 25 amperes, but not less than 2 amperes until all cells are

BCI Battery Technical Manual

BCIS-08 REV

DEC02

Current Revision: 2002-12

BATTERY TECHNICAL MANUAL BCI CYCLE LIFE TESTING OF

DEEP CYCLE MARINE / RV BATTERIES

TABLE OF CONTENTS

1 Scope and Classification 2

2 Cycle Life Test Conditions 3

3 Test Procedure 5

4 Performance 6

1 SCOPE AND CLASSIFICATION

1.1 The purpose of this specification is to provide a method for testing the life of deep cycle

marine/RV batteries in a charge-discharge cycling mode It is recognized that these batteries are used in a variety of deep-cycling applications which range from marine trolling motors to RV’s to electric wheelchairs and typical discharge rates will vary widely This laboratory procedure, while not intended to simulate field usage or battery life in normal service, is designed to provide a standard basis for user comparison of products and for the evaluation

of performance in the production and development of batteries by manufacturers

1.2 Most applications operate with nominal 12-volt systems A discharge at a current of 25

amperes has been found to be appropriate The BCI test operates with a 25-ampere

discharge simulated by an electronic load and specifies current limiting constant voltage charging

1.3 The measure of performance of a battery is the number of cycles (charge/discharge) until the

discharge capacity in minutes at 25 amperes falls below 50% of manufacturer's rating in minutes at 25 amperes Users requiring a higher capacity cutoff should be able to get an appropriate value for cycle life from their battery manufacturer

2 CYCLE LIFE TEST CONDITIONS

2.1 Pretest Conditioning Procedure

2.1.1 All industry-sanctioned and approved standards are established on new undamaged (60 days

or less since date of manufacture), fully charged batteries The following conditioning

procedures have been established as a requirement prior to laboratory testing

2.1.1.1 Flooded Electrolyte with Cell Access

2.1.1.1.1 Each battery shall be charged at a whole number ampere rate between 3% and 4% of

the rated or expected minutes of discharge at 25 amperes, but not less than 2 amperes until all cells are gassing freely, and temperature corrected on-charge terminal voltage and

electrolyte specific gravity readings are constant over three successive readings taken at one hour intervals

2.1.1.1.2 Both on-charge terminal voltage and electrolyte specific gravity decrease with increasing

battery temperature and vice versa Correct readings to a base temperature of 26.7°C (80°F) Correct voltage by 0.0063 volts per cell per °C from 26.7°C (0.0035 volts per cell per °F difference from 80°F) Correct specific gravity values by 0.00075 per °C from 26.7°C (0.0004 per °F difference from 80°F)

2.1.1.1.3 During the period of charging, the electrolyte temperature shall be maintained between

15.6°C and 43.4°C (60°F and 110°F)

2.1.1.2 Flooded Electrolyte Without Cell Access

2.1.1.2.1 Such batteries shall be charged in a 26.7°C ± 1°C (80°F ± 2°F) water bath by either of

the following procedures:

2.1.1.2.2 Constant Voltage Charging Procedure

2.1.1.2.2.1 Each battery shall be charged for 24 hours at a constant voltage of 2.67 volts/cell with a

charger having a minimum capacity of 20 amps

2.1.1.2.3 Constant Current charging Procedure

2.1.1.2.3.1 Each battery shall be charged at a whole number ampere rate between 3% and 4% of

the rated or expected minutes of discharge at 25 amperes, but not less than 2 amperes, until the on-charge voltage across terminals changes less than 008 volts/cell per hour over three successive reading at one hour intervals

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 25 amperes Since the test battery assembly usually consists of a single 12-volt battery, the final discharge voltage measured at the battery terminals will then be 10.5

± 0.10 volts

2.4 Temperature

2.4.1 The battery shall be tested in a water bath maintained at 26.7°C ± 1°C (80°F ± 2°F

(nominal)), and shall be allowed to reach thermal equilibrium by open circuit stand in the bath for up to 24 hours Water level of the bath shall be maintained at a height equal to or greater than 75% of the height of the battery container

2.5 Specific Gravity

2.5.1 For batteries with flooded electrolyte, specific gravity shall be as specified by the battery

manufacturer for the fully charged battery

2.6 Readings

2.6.1 In order to ensure the test is being conducted according to the parameters of this

specification, the following readings shall be verified and recorded at least once a week during a cycle of the test:

Discharge Current Water Bath Temperature

Charge Voltage Number of Cycles to Date

Charge Time % Ampere Hour Returned per Cycle

Discharge Time

2.7.1 All equipment shall be clean, in good working order, and calibrated

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 ± 0.1% Timers shall have an accuracy of 0.5% or better

3 TEST PROCEDURE

3.1 The battery may be preconditioned as described in this document before start of life test

Discharge tests for battery rating measurements may be carried out prior to the start of life

testing if desired, however, these discharges will not be counted towards overall cycle life of

the battery

3.2 Discharge shall proceed at 25 ± 0.25 amperes until the on-load battery voltage measured

across the battery terminals falls to 10.5 ± 0.10 volts After the cutoff voltage is reached, the

battery is allowed to sit at open circuit until the total time for discharge and open circuit is 4

hours

3.3 The battery shall then be recharged according to the table below for the specific construction

Electrolyte Electrolyte Sealed

Returned Per Cycle

Returned Per Cycle

*Maximum voltage must be changed to the specific manufacturers published value, if

different

**Time may be extended if returned ampere hours do not meet minimum % ampere hour

returned This time must be established at the beginning of the test and cannot be changed

3.3.1 The charger shall be current limited constant voltage The voltage during charge shall be no

more than listed above for the particular battery type tested The charge portion of the cycle

shall be terminated when either the maximum time or percentage of ampere hour returned

has been obtained If the charge is terminated by percentage of ampere hour input before the

maximum time is reached, the battery will be allowed to sit open circuit until the maximum

4 PERFORMANCE

4.1 Cycles of life to 50% of manufacturer’s rated capacity in minutes at 25 ± 0.25 amperes shall

be reported Since each discharge is to 100% of the effective depth of discharge, the capacity versus cycle life curve will usually be a smooth arc