strange battery problem

[skicat]

I hope someone can make sense of this. Battery checks out fine and is fully charged. When installed in boat it goes dead after 7-10 days. ONLY thing drawing current is a small analog clock. Bought brand new battery, installed in boat. Works fine and does not go dead even after 2-weeks. Had old battery that went dead tested again and fully charged. It has now sat on my work bench for 2+ weeks and is still holding charge. Any explanations?

 

[rickdb1boat]

Re: strange battery problem

Did you have the old battery load tested at the local auto parts store? A dead cell will also cause this. In any event, you have cured your problem...

 

[skicat]

Re: strange battery problem

Yes. The local NAPA store tested it twice. In early May before the problem occured, and again early July. They found no problem. The battery is three years old and has been run dead when the previous owner did not remove it for the winter.

 

[rickdb1boat]

Re: strange battery problem

Running it dead will do it!!

 

[cp]

Re: strange battery problem

The problem with the old battery is...it's old . As it gets old the plates inside become less able to take and provide a charge. Think of the battery as a glass which you pour water into (charge) and out of (discharge). Over time the glass develops sediments on the inside, so even though you can still fill it with water (fully charge) it actually holds less water (because of the sediments) so when you pour the water out it doesn't take as long before it's empty. Hope this oversimplification helps.

 

[skicat]

Re: strange battery problem

I think I understand. Even though the battery tests good, and holds a charge when not under load, it drains much faster than it should even under a very small load. Is this battery good for anything or should I dump it?

 

[cp]

Re: strange battery problem

You get to make the final decision, but if it were me, I'd keep using that old battery until it really died. I wouldn't use it as the only battery on my boat, nor would I depend on it where large reserve capacity was absolutely required, but otherwise, it tested OK so I'd use it.<br /><br />I'd use it to start my motor, as long as the motor's alternator charged it and I could switch to another battery "in case." I'd use it to run the stereo or night fishing lights while at anchor as long as I could switch to another battery to start up. I wouldn't count on it to run the bilge pump on a non-self-bailing boat left in the water, nor to run a trolling motor for very long. Heck, I'd even use it in my car, but then I live on an island so when it really died, help wouldn't be very far away .