Sealed Wetcell batteries

[Joe500]

I have two Group 31 Wetcell batteries made by Interstate. I purchased one 2 years ago and another 1 year ago. They are unusual in that there is no place to add water, as far as I can see. As the marine store told me, they are "sealed." I paid about $100 for each. A few months ago, they discharged completely, as the boat was on land for winter storage and the automatic bilge float switch got stuck in the on position. I don't know if they froze in the cold. But a week later they were down to 5 volts. I've charged them for about a total of 20 hours now and they don't go any higher than about 11.5 volts. I assume I need new batteries.

My question is, should I buy the same kind of batteries or would I be better off with the normal wetcell batteries that I could add water to? If had been able to add water to these, would I still need to replace them? Or could it be that my dealer was wrong and there is in fact some way to open the ones I have and add water?

[bill good]

Disconnect battery next year!! I think you need a new battery.
However 20hrs charge @ what rate of charge? are they both 11.5v? Have you checked with a known good voltmeter? Batteries don't like being discharged.

[camaraderie]

Yeah...they are toast. Get regular wet cells, keep em topped up and Charge them FULLY next winter before disconnecting them. Monitor their charge level a couple of times over the winter and if they drop to 12.2V or lower...recharge them.
Note also that a wet battery that is fully charged will NOT freeze. A discharged battery at 50% will freeze at about -20 degrees. Not a problem in NY...but freeze temp rises as you discharge below 50%. Hence my 12.2 volt caution!

Self discharge in wet cells is around 5% a month typically so even if you only check voltage every couple of months after fully charging, thy should be OK.

Altrernatively...you can spend the extra bucks for sealed AGM's and charge 'em up and forget them all winter as self discharge will be negligible.