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Old 04-14-2010, 09:59 AM   #1
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What is drawing on my aux battery ?

The Aux (house battery) only lasts about a day. Everything is turned off. How do I check to see what is drawing on it or if there is a short?

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Old 04-14-2010, 11:51 AM   #2
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Re: What is drawing on my aux battery ?

Originally Posted by debraleehayes
The Aux (house battery) only lasts about a day. Everything is turned off. How do I check to see what is drawing on it or if there is a short?
Someone might chime in with a better cool elegant solution..

Hopefully it's really not the battery and it's short without a fuse or something drawing alot of 12V amps.

First off, Disclaimer, We are talking about the "House" battery and not the engine/starter battery system.

In my case, this is how I do it. Process of elimination.

Find your house battery and try to determine where each positive/negative 12v connection goes to.
For me, my battery connections first branches to the inverter and also to a central 12v cutoff switch where all the house lights and devices are connected too.

The 12v cutoff switch connects to a bank of 12volt fuses that branches to other 12v "House" connections like your lights.

In my case, turning off the 12v main cutoff switch leaves my battery only connected to the inverter.
By turning off the 12V cutoff switch, the problem may be with the inverter.
Test to see if it survives more then a day with the 12V cutoff switch turned off.
After confirming that the battery lasts with the inverter(with inverter turned off for sure, check) as the only connection, proceed to turn on the 12 V cutoff switch where all the other 12v items are.

In my case, I have an amp meter on that 12V cutoff switch that tells me how many amps I'm drawing. So you can add an amp meter to see if you have anything drawing power to that branch.

In my case, I have a fuse box after the main 12V cutoff switch so I know what each fuse goes to. My fuse box has a switch associated to each fuse. I turn them all off and watch the amp meter. Should be zero. Anything else drawing current (amps)? Then I turn each switch/fuse on and watch the amps climb. Or test and see what the amps are with selecting each one by one. eventually you'll see the bad apple drawing an abnormal amount of current, so close that it doesn't pop the designated assigned fuse. For example, you somehow have a 30amp fuse so it's like not reaching 30amps, only 27amps but 27amps is alot of current draw.., change the fuses so it pop's at 15amps or even less 10amps to see where the draw or short is.. trace that sucker and see what it is, a short? Bad wire? Disable that branch, and test the rest..

Note: if you don't have fuses inline to the connections to your house battery, I suggest you try adding in fuse connections inline with 12volt fuses rated at 5,10,15,30amps to the incoming connections.
Obviously I would not do it to the inverter power lines or anything extra thick. But something is drawing more then 10,15,30amps on your battery killing it, or the battery is just not holding a charge like it seems.

I have a few tools available to list like my watts-up amp meter, the link monitor if you need it. Simple voltmeter with ability to read amps can help too.

Hope this helps, it can be a pain if you have alot of 12v devices like I do, but it's blissful to know your not drawing "ANY" amps with the master 12v cutoff switch is turned off; lol

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Old 04-14-2010, 03:49 PM   #3
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Posts: 125
Re: What is drawing on my aux battery ?

Is this a recent thing? Have you changed anything just prior to the charge dissipating in only a day? How old is your battery? What size is it?

If you haven't changed anything and your not blowing fuses and your sure everything is turned off and your battery is a couple of years old you may want to get it tested and see if it is toast.

I know this may be the obvious one but start simple..
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