The only way to measure percent charge is with hydrometer. Voltage is a rough estimate at best.
What is battery ampere hour rating? If a 100 Ah then all day does not surprise me if really discharged. Sitting in corner of shop for a long time can sulfate em right good especially so if you did not charge before storage. Time to charge can be estimated by Ah X 1.3 divided by charge rate ie 6 amps. 1.3 is from personal observation of charging submarine battery - you end up putting in 1.3 more than you take out. This probably comes from running cell voltage up to 2.51 plus a temp correction to drive off sulfation. Much of the .3 extra goes into heat and generation of hydrogen I think.
Is meter on charger correct?
Dan Bentler
Last edited by leitmotif; 12/28/2010 6:56 AM.
