Slow down, Rock!
Lead-acid batteries are pretty simple critters, and they don't (often) just die. Two things to check - they are related and either will do for starters - are the voltage across the terminals and the specific gravity of the acid. The voltage on a 12v battery (fully charged) should actually be about 13.2 volts (2.2v per cell x 6). You mentioned that you were charging from dock 12v.... is this an actual battery charger? That is important because a charger will put more than 12 volts - often up to 15 volts (max charging voltage is mostly a function of how much current the battery can take, how fast you need to charge it, and how much it can/will heat up) - across the battery to charge it. In short, if you're not putting enough voltage/current across the battery terminals, you might not be able to charge it. These batteries might be so dead that they need an 'equalizing' charge, and that takes higher voltage and current capability than a small 'trickle' charger can provide. You also might be charging the batteries with your small charger, but at such a slow rate that you can't tell it is happening (which is where the volt-meter sometimes comes in handy!) You mentioned the liquid was 'very low'. That's not good because the exposed plates can get 'corroded' (I used to know the technical term for that, but it's been years) and won't take a charge. Here's a suggestion: Take the batteries out of the boat and down to any auto parts store. Have them hook them up to their (industrial strength) charger. They can tell you if the batteries are indeed fried or not - in about an hour. Then, if they are actually fried, you can probably get some trade-in for them as well as having disposed of them properly! Good luck! And don't give up the...... batteries! without a fight! Cheers, Bob s/v X SAIL R 8
