This life test simulates automotive service where the battery operates in a voltage regulated charging system. This test subjects the battery to charge and discharge cycles resulting in failure modes comparable to those encountered in automotive service.

1. 1 The battery is tested in a water bath maintained at 105 ± 5 F.
2. 2 The test cycle is performed as follows: Discharge: 2 min at 25 A Charge:
   1. (a) maximum voltage — 14.8
   2. (b) maximum rate — 25 A
   3. (c) time — 10 min
3. 3 The battery is continuously cycled for 100 h (for example, Mon day noon until 4:00 p.m. Friday). A switching delay of not more than 10 s is permitted from termination of charge to start of discharge, and termination of discharge to start of charge.
4. 4 The battery is given a 60 h stand on open circuit in the water bath.
5. 5 Discharge battery at a rate equal to its 0 F cold cranking discharge rate in amperes, at the battery temperature obtained in paragraph 4, to an end voltage equivalent to 1.20 V per cell, or a minimum discharge time of 30 s, whichever occurs first.
6. 6 Replace battery on the cycling test without a separate recharge. Start on the “charge” portion of the cycle.
7. 7 The life test shall be considered completed when the battery fails to maintain 1.2 V per cell for a minimum of 30 s on the manual discharge (paragraph 5). The point of failure shall be determined by plotting the 30 s discharge voltage values.
8. 8 Water should be added as required during the cycling portion of the test. note: This test only applies to 12 V batteries of 180 min or less Reserve Capacity.