How much damage done to my AGMs

[silvercreek]

The boat was hauled out for 10 days and when I picked her up, I discovered the yard had not plugged in the shore power as promised, and the dual-purpose AGM batteries (5 x 95Ah Exide EK950) were depleted to 11.42V (under slight load).

After charging up to 100% over a 24-hour period they "seem" to be holding charge relatively well, though not quite as well as before. It's hard to quantify exactly but I would guess they drain something like 5-10% faster than before. Really hard to tell though.

Any way to estimate how much damage was done? I'm trying to determine if I need to replace them now or if I could get another year or two out of them.

[rslifkin]

They weren't fully drained and it was just once and not for a long period. So it likely caused a little bit of sulfation, but it shouldn't have done any major damage. I'd draw them down a bit and recharge again, then see if you can hold them at absorption voltage a bit longer than normal. After that, see how they perform and go from there.

[grantmc]

Silver Creek no one on the forum could really make a better guess at the answer you ask for than you can yourself. Factors like battery age and condition, and their usage, storage and history will all factor in. But we all do know AGMs do not like being discharged.

Given that they took up a charge, that's a really positive sign. But the discharge wont have been good for them Fingers crossed they're ok. But you do now know it's at least time to start setting aside a few bucks each month for the inevitable replacement that's been brought forward from when ever in the future you expected them to need swapping out.

[silvercreek]

Thank you both. Gives me hope that the batteries will be ok.