Dead Battery ?

[sailrj]

On my Beneteau 351- turned the charger off 10 days ago, checked yesterday and the 220ah AGM house battery was dead. All the breakers, except for the bilge pump, were off and the house battery appeared to be fully charged when I turned the charger off. The starting battery was isolated from the house battery. The house battery is 3 months old and appears to be taking a charge when I turned the charger back on. No obvious source of power draw, and the bilge is dry!! Would greatly appreciate anyone's knowledge with similar experiences so I don't have to reinvent this wheel. HELP!!!!!!!!!

[s/v Moondancer]

You need a battery monitor to check the ongoing draw down.

However, last time that happened it was a relatively 'new' but bad battery which was easily checked using a load tester.

[Blue Stocking]

Stereo with permanent memory powered up?
Inverter with "load seeking" left on.
Some VHF radios with DSC bypass on/off switch

All those little draws, over 10 days, add up.

[ShaunJ]

As Moondancer suggested, get the battery load tested. Most auto parts stores can do this for you. This will give you a great start in finding the problem. If the battery is OK, then you know you have a drain on the battery that you have to find.

[Cheechako]

is that battery quite hot when charging? I have had this occur with fairly new batteries that had an internal short. The battery charges up but wont hold a charge for long. I finally figured it out after leaving it charging and was down in the compartment and it was real hot...

[noelex 77]

Turn everything off and use a multimeter on amps in series between the battery and battery lead. Find if there is a current draw, my prediction is there is something drawing power. Disconnect things till you get this down to zero.

[mrm]

sailrj, since you mention it is a new battery (3 month) and you did not say anything about having this problem earlier, I assume it is something to do with the battery. Probably internal short (quite often resulting from some plate mass breaking away and falling to the bottom from too rough handling), but, as already suggested, measure with an Amp-meter if there is any draw when systems are supposed to be off.

Did your previous home battery fail from age or prematurely?

[Extemporaneous]

Originally Posted by mrm

Probably internal short (quite often resulting from some plate mass breaking away and falling to the bottom from too rough handling), but, as already suggested, measure with an Amp-meter if there is any draw when systems are supposed to be off.

Not with an AGM Battery.... at least not that I know of.

Cheers,
Extemp.

[mrm]

Originally Posted by Extemporaneous

Not with an AGM Battery.... at least not that I know of.

Not completely unheard of, but very rare indeed.
Let's see what OP answers to questions asked so far.

Greetings,
Marius

[Extemporaneous]

Originally Posted by mrm

Not completely unheard of, but very rare indeed.
Let's see what OP answers to questions asked so far.

Greetings,
Marius

Really, I've completely unheard of that!
Can you point me to where I might read about such a case. Thanks.

Okay, you let's see.

Thanks,
Extemp.

[knotnow]

Originally Posted by mrm

Probably internal short (quite often resulting from some plate mass breaking away and falling to the bottom from too rough handling)

Originally Posted by Extemporaneous

Not with an AGM Battery.... at least not that I know of.

Yep just what Extemp said. Absorbent Glass Matt (AGM) batteries leave very little wiggle room around the AGM part for a shock to be severe enough to damage plates without physically and visually damaging the battery

Originally Posted by Blue Stocking

Stereo with permanent memory powered up?

Originally Posted by Blue Stocking

Inverter with "load seeking" left on.
Some VHF radios with DSC bypass on/off switch

All those little draws, over 10 days, add up.

That would be my WAG