If You have a shorted cell most of the time it will show less voltage 1 bad cell will be 10 volts . If You put a volt meter on the battery and turn the lights on the meter should read 12 volts if the voltage takes a dive to say 10 volts right away it means one of the cells is shorted or if You charge the battery and right after You charge it the voltage drops to 11 or 10 volts, bad cell.A volt meter even a cheap one is a great tool for the garage .
Pete
