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Drain on the battery

April 27, 2020, 09:26:05 pm

Hi Guys,
Hoping everyone is staying well.
I have a large drain on my batteries, in the past two days from 12.6 to 12.1, not sure what is happening.
I have 3 8g8d gel batteries, fairly new.  Nothing wrong with the batteries, but the problem is the drain.
I have the shut off mechanism on, but still I lost the voltage.
Anyone had this problem? Does anyone have an idea where the problem is in the coach?
Thanks for your help.

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Re: Drain on the battery

Reply #1 – April 27, 2020, 11:49:03 pm

Disconnect the alternator output wire. Charge the batteries back up and see if the drain stops. Diode could be bad in the alternator and the isolator might be letting it backfeed. If that doesn't help start removing fuses one at a time with a 12 volt test light in series from the ground post on the battery to ground with the ground cable off. When the light goes out you have found the bad circuit.

 In the future post this type of question under "tech talk" you will get more replies.

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Re: Drain on the battery

Reply #2 – April 28, 2020, 08:43:31 am

Moved to Tech Talk.

Brett/moderator

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Re: Drain on the battery

Reply #3 – April 28, 2020, 09:28:51 am

I always start at the beginning.  Charge the batteries then "lift" one of the connections, that is to say pull one of the battery cables from the battery so no current can flow.  3 hours after disconnecting the batteries measure and record the voltage.  Come back 24 hours later and measure the battery voltage.  This will tell you if the battery(s) are internally shorted.

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