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Battery Problems

May 15, 2017, 08:50:51 pm

Have 3 8D MC gel batteries.  Was having problems so I disconnected all loads at both negative and positive posts, but left the three batteries connected together.  After several days I checked the voltage and it read 13.6 volts???  Thought fully charged batteries had a voltage of 12.8.  Batteries are 2012 vintage so are ~ 5 years old.  Any ideas? 

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Re: Battery Problems

Reply #1 – May 15, 2017, 09:29:18 pm

Sounds like the batteries have a surface charge on them. First I would remove the cables from the batteries and check the voltage on each one. But you need to have them load checked to really know the condition. What kind of problems where you having to start with?

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Re: Battery Problems

Reply #2 – May 15, 2017, 09:40:32 pm

Yes, likely they are holding a surface charge.  Turn on a small amp load, and voltage will quickly drop to the 12.8 or so volts.

This does not give an indication of a good or bad battery-- just the way they work.

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Re: Battery Problems

Reply #3 – May 16, 2017, 01:00:15 am

Double check to be sure nothing is connected to batteries.  The batteries can be connected, but nothing else.  How did you disconnect all loads?

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Re: Battery Problems

Reply #4 – June 17, 2017, 02:36:57 pm

Thanks for the quick replies.  Here is what I found.  I thought I knew how the batteries were connected, but I didn't.  Previously I owned a New Horizon's 5th Wheel trailer for 12 years.  It had two 6V Life Line batteries connected in series.  I just had to open the top of the battery box to check on the batteries.  Easy peesy.  Not so with my current rig.  The battery compartment is buried in the center of the motorhome in the joey bed bay.  In the compartment are three 8D 12V batteries wired in parallel, each wire to each other.  I located the negative wire that goes to the coach electronics and disconnected it thinking I had disconnected the battery bank.  Wrong!!  Since all the batteries are wired together this procedure only disconnected one battery.  In the end I had to disconnect all the negative post wiring for all three batteries to kill the power to the coach.  What a pain.  After consulting the wiring diagram for the coach I determined I could more easily disconnect the battery bank by disconnecting all the negative connections in the power center bay.

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Re: Battery Problems

Reply #5 – June 18, 2017, 09:21:16 am

You should have just disconnected the one negative cable exiting the battery compartment, not going to another battery.

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