The 12V battery will not likely be 13.8V at the few mA that will flow through the "6V" battery so you will probably be supplying too much voltage to it and you risk doing extra damage (though it sounds like this battery may be terminally defunct).

I don't understand why the off load terminal voltage should fall after a period of gentle charge.

 

My guess - and it's just a guess - is that perhaps during the charging phase I'm producing gasses that limit the amount of contact with the plates and the electrolyte. But that's just a guess. And for what it's worth, I think the battery is toast as well. If something significant - or even suggestive progress by this weekend I'm going to put it in the recycle bin. Like I said, this is a 6 volt battery that I don't specifically have a use for. Hate to lose the stock but sometimes we need to clear out unused stock and make room for more useful stuff.

Thanks all for the direction.

 

Hate to lose the stock but sometimes we need to clear out unused stock and make room for more useful stuff.

Have you been talking to my wife? All the good crap I've accumulated and she's always on me to get rid of it since I haven't used it.

 

Still, leaving a SLA battery uncharged and abandoned for years is a sure way for the plates to sulfate badly.

Does that go for a new battery that was never put in service too? The reason I ask is I have an ongoing car project, that will need a battery some day. I got a really great deal on an Optima AGM battery from a place going out of business and bought it. But it's still sitting on a shelf. Is it toast now?

 

Is it toast now?

Can't answer for sure, but I THINK a wet LA battery is a little more tolerant of sitting. Still, I would recommend periodic charging just to be on the safe side.

You can always go test it to make sure it's not nackard.

 

Does that go for a new battery that was never put in service too? The reason I ask is I have an ongoing car project, that will need a battery some day. I got a really great deal on an Optima AGM battery from a place going out of business and bought it. But it's still sitting on a shelf. Is it toast now?

You do need to keep it charged. It will self-discharge and then the lead sulphate can form and that's lead that can no longer play a part in the battery function.

 

You should buy a small, smart battery charger than can do a float charge to keep the battery charged and keep it continuously connected to the battery.
Otherwise in a a few months (or sooner) it will start to sulphate, which generally cannot be completely reversed.

 

Thank you all. I'll have to dig it out and check it. I always thought a battery that had never been used or given a real charge was stable.

 

I always thought a battery that had never been used or given a real charge was stable.

I don't think that's true of any battery chemistry except possibly zinc-air for so long as you keep the air out.