Severely discharged battery...does it need to be replaced?

[josrulz]

Perhaps a better question is, how do I tell if it needs to be replaced?

Here's what happened. I'm religious about turning off the battery switch--everything completely off--when I leave the boat (bilge pump is direct). Except this one time I forgot. Yeah, I'm irritated with myself, but there's nothing I can do about it now.

One battery was left on via the main selector switch, and there was some load on it due to some electronics on from the DC panel (argh). A whole week went by, and the battery was tanked. On the voltmeter, it read about 10 volts--eek!

I don't have a battery charger, in case you haven't guessed. So I brought a portable smart charger from home, disconnected the battery, and recharged. It's currently reads 13.04 volts on my multimeter, and seems to be holding.

Some other facts: the battery is an Interstate deep cycle battery, 12v.

OK, so having said all that, and still being irritated that I left that switch (and electronics) on, how do I know for sure that the battery is still usable, or if it needs to be replaced? I'd rather not just go with trial and error on the water, since I'd like to know I can depend on it.

Thanks for your suggestions!
-J

[erps]

how do I know for sure that the battery is still usable, or if it needs to be replaced?

The short answer is by using it and observing how it performs. You've lost some life, but batteries can survive some abuse.

My son ran the battery dead on my truck last week. I charged it up and started using it like normal. It's been holding a charge and it starts the truck, so I'm not going to replace it until it doesn't hold a charge or start the truck.

[PaulinVictoria]

Take it to a battery testing place

[SHNOOL]

deep cycle and interstate mean SHOULD be ok, depends on age? Generally a deep cycle can take some of this... partially deplete and recharge, and wait and see.

[josrulz]

The batteries are only a bit over two years old. And yeah, I was thinking the same, that they SHOULD be able to take some abuse. But what the heck do I know?

I'll use the battery some, and see how it goes. I'm not really against replacing them, I'd just like to get some more use out of them if I can.

Thanks for the responses folks.
-J

[TQA]

Like others say you have shortened its life and it will not have the capacity it used to have.

But keep using it. A usefull test is to charge it, then accurately measure the voltage after a short period of use to kill the float charge, it should be above 12.7 leave it a week then check the voltage again. If it drops down to 12.4 or less it is u/s.

[Stu Jackson]

Download and read the Ample Power Primer, Ample Power Company Home Page, tech tab. It discusses bringing old batteries back to life, see Breaking in New Batteries.

You may not have a problem.

[josrulz]

Thanks folks.

I charged it and the other battery back up (separately), and now have them all hooked up again. For what it's worth, I started the engine on the aforementioned drained battery after the full recharge, and it started right up, and still showed 13 volts afterwards. We'll see how it's doing after some time goes by...
Thanks!
-J

[bandaidmd]

Deep Cycle= designed to be repeatedly drained and recharged. Some would argue you shorten there life by not doing this.

[mitiempo]

True, to 50%. Deeper discharges will shorten life by a large amount.