Join Date: Aug 2006
Location: Arlington, VA
Thanked 11 Times in 9 Posts
Rep Power: 10
Sounds very much like you have a serious problem, and one which could easily cause a fire.
I agree with dog, but think you need to look further than the cables as well. A looksee by a qualified marine electrician would be a good thing to do; well worth the cost.
I think you're looking at replacement of the batteries, the cabling, the battery charger and, possibly, the regulator for your alternator.
This is what I'd be thinking of doing if it were my boat. Piecemeal changes will almost certainly continue to give you grief. If you make the investment in correcting the whole system, you'll not have to worry for many years to come.