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Redram99's avatar
Redram99
Explorer
Apr 25, 2018

Batteries not charging while chassis engine running

Hi all
I have a 2010 triple e senator class c. Ford v10.
Recently I noticed my house batteries weren’t charged after a long road trip. Even when the v10 was idling the house battery voltage didn’t match the chassis battery voltage. As soon as I plug into shore power or fire the genny the house batteries start to charge.
In my battery compartment I have a 12v dc coil and a bi directional isolator relay delay.

I have 14v to one side of the coil while the engine is running but it doesn’t continue thru the coil to the house batteries. It appears that the bi directional isolator “runs” the coil??

As a quick fix, I jumped a wire direct from the chassis side of the coil direct to the house batteries so they would charge while driving. Quick fix but now the house is also running off the chassis batteries which could cause issues(dead battery and no engine start)!!!

Would it be the coil or the isolator that is broken? How do I figure it out?

Ps. I am probably the worlds worst electrician...

Thanks in advance.

Jamie

14 Replies

  • tobydad wrote:

    I had the same problem and changed the battery isolator solenoid and that solved the problem.


    Me too. On TWO used Rvs; one a C and one an A.
    Seems to be a common failure point.

    An RV service center should only charge you a half hour labor to put a new one on. IIRC, price of the part is about $50.
  • Start with the simplest first. Remove and clean all house battery terminals and make sure they are tight.
    I had the same problem and changed the battery isolator solenoid and that solved the problem. The most difficult part was reaching the solenoid which was inside a storage cabinet where all the wiring came together. Easy to replace as long as you disconnect and connect one wire at a time.
  • Normally a B.I.R.D., senses when the chassis batteries have reach a full charge and energizes a relay or solenoid, whatever you wish to call it. When the solenoid energizes, the house batteries receive power from the chassis alternator.

    There should be two heavy wires attached to the contacts and one small wire to the coil of the solenoid..

    Jumper from the hot side of the solenoid to the smaller wire,if the solenoid makes a loud click, it would appear to be working and using atest light or DMM connected to the load side of the slenoid should light up.

    If you start the engine and allow it to run for a few minutes, the BIRD should send 12 volts through the small wire on the coil of the solinod. A test light connected to that small wire and ground should light up when the chassis battery is charged enough and the BIRD sends power through that wire.

    If after starting the engine and letting in run for 10 or 15 minutes and the test light doesn't come on, it would seem you have a bad BIRD.

    You should be able to search on line and find more concise testing instructions.