I purchased an 89 Hunter 30 Aug. 1. It had a K-Mart battery charger installed at the time. I have not had any trouble with the batteries in the first 3 weeks. Sat, I arrived and both batteries were dead. Replaced the Kmart special with a 20 amp Statpower Trucharge marine charger. Next day one battery was at 12 volts and the other at 7 volts. Started engine for a run, went at 2000 rpm for 25 minutes, then increased to 2600 rpm. for another 10 min. when an engine or battery warning signal sounded for 10 sec. (Being of the age of reading glasses I couldn't tell which warning indicator lit but it was the third light from the right). Immediately put the boat about, went to neutral gear and dropped to 800 rpm. limped to harbor with no more warning signals. Rechecked oil, water, alternator belt all fine. I suspect the batteries are bad but wonder if it could be the alternator. Does anyone know the warning light locations? Any suggestions? Thanks for the help.