[sundog01]

Went to the boat last weekend and my battery charger died, unknown to me. I thought that the batteries were full charged - however - the next morning both were dead with the charger on. Went and borrowed another battery charger and it took all day to charge 1 battery. Next day the same battery was down to 10 volts. I finally got the motor started and fully charged both batteries according to the volt meter. I realize the volt meter is no indicated of amperage. I then had to leave the boat.

My questions are - could the malfunctioning battery charger kill my batteries?
What would cause a fully charged (supposedly) battery to lose charge overnight, with nothing on and the battery switch off?

The charger is of unknown age and the batteries are 2 years old, deep cycle.

I plan on replacing both batteries and the charger.

Thanks for your help.