Re: Electrical Drama--Help!
The surest easy way to measure the battery charge with wet cells is testing the cells with a hydrometer. There are electronic meters available that remain connected to the battery, and count amps in and amps out. After calibration they calculate percent of charge, but they are for upper budgets.
Otherwise, a full battery bank will measure about 12.7 volts after 24 hours with no charge and no load. Batteries will read a "surface" or "face" charge of 13+ volts right after coming off of a charger, even if the capacity has not been fully refilled.
Also, deep-cycle batteries are usually rated at C/20 - constant discharge at 1/20 of the rating for 20 hours. So a pair of 200 AH 6-volt batteries will give 10 amps at 12 volts for 20 hours. They will usually not last a full 60 minutes at a 200 amp draw.
It needs to be said over and over and over - clean and tighten all your connections. You would be surprised at the number of starters, alternators, and batteries that have been replaced unnecessarily because of a spot of corrosion on a connection.
Someone said "Making good decisions comes from experience, experience comes from bad decisions." I say there are three kinds of people: those who learn from their mistakes, those who learn from the mistakes of others, and those who never learn.