Low AGM Batteries

[WA116]

I am sure this has been covered.., but I couldn't find it.

I did read the "Study Hall"

Last year i acquired my first boat with an electrical system - it has two Optima AGM batteries labeled "Bluetop Starting". One is pretty old - 10 years, and the other is newer - 2 years. They start the engine and run a simple electronic instrument system. They are each 50 AH.

When i bought the boat, i asked the PO what he did over the winter with the batteries, and he said "nothing".

I put them in my garage.

Now, when i put the multimeter on them they both read 12.08 V

Is that a problem?

can i just put them in the boat.., try to start it (13hp volvo saildrive), and hope they recover?

[smac999]

Charge them back up.

I would replace the 10 year one.

[Marathon1150]

Originally Posted by smac999

Charge them back up.

I would replace the 10 year one.

I agree with both statements. Ten years is a long time even for a high quality battery like Optima. And, though I am not an expert, pulling power from a battery that is reading below 12.2V or so, can't be good for it.

[WA116]

thanks


the boat yard put them on a charger for me.


if the old one won't charge, i will replace it.



In any case, I would be fine with one good battery - i rarely go more than 5 miles from my mooring. My previous boat - a 33ft OD racing boat - had no motor, so I always sailed it to the mooring.

[Pete7]

It doesn't need to be a replacement Optima either, if you have really low power requirements and a small engine.

Pete

[a64pilot]

Doesn’t matter if it charges or not, unless you do a capacity check you won’t know if its good or not, at least put one of those cheap battery testers on that look like a heater, they throw a load for 30 sec or so and you read the voltage.
But 10 years on a battery is exceptional, that battery owes you nothing, replace it before it goes dead on that holiday weekend that all the stores are closed on and you want to go out with friends.