July 2013
I have eight six volt lead acid batteries that provide “house” power for my boat. The batteries have run dry on several occasions. It’s hard to tell if the “run time” has been adversely affected since I don’t usually allow them to fully discharge. Have they likely been damaged, and if so, will equalizing them restore lost capacity?
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Yes, they have likely been damaged, I had to look up what "equalizing" a battery was since I wasn't sure. Equalizing may help but I doubt that full capacity will be restored, or if it is, it will last very long. I'm going to assume that these batteries are the deep discharge type and so you may be able to restore them at least partially.
I've noticed with my backup 12 Volt deep discharge 70 - 80 AHr batteries for amateur radio & emergency use that once I let them get even partially dry I can never get them back up to full capacity. On the other hand, I do not own a charger that can perform the equalization charge either. So, I'd say since it likely won't hurt, give it a try.
My question is: Since you never run them down, you have no way to compare to see if this has improved anything, and also, since you never run them down, why worry about it? You never seem to need whatever the full capacity is anyway.
You may contact me if you like. I'm interested since I've done battery work both professionally at Marsh McBirney, Inc., and Gardner Labs, as well as in my amateur radio hobby.
I have heard that If you let car batteries completely discharge, they will lose one-third of their capacity.
