- Feb 6, 1998
The best way to determine this is to charge to 100% then isolate all the batteries from one another. Now wait a few days and test the voltage of each battery. If they had previously been in parallel your voltages should be within .02V of one another.. So a reading of 12.72V, 12.71V, 12.70V and 12.55V would be a bad indicator for battery number 4 (12.55V)...