Forum Discussion

BGummer's avatar
BGummer
Explorer
Oct 05, 2019

Battery Wiring Question

Ok, I’m a first time travel trailer owner and not very knowledgeable when it comes to generators and batteries. I just bought a 2001 Thor toy hauler. It has a Onan 4000 generator which was not running. I replaced the starter after a couple other repairs and got it up and running - so I’m not completely useless when it comes to mechanics.

Question:

There are two 12v batteries on the front of the trailer. One is Connected directly to the Onan generator. The other is connected to the trailer. Is that correctly setup? One battery to run the trailer? In my mind I could connect the to in a parallel and have two batteries. However I see the issue could be running them both down and not being able to start the generator. Any thoughts on this? Just leave as is? Add another battery for starting the generator and then connect the others parallel? Just trying to get the most out of the batteries. I will he dry camping in the great outdoors - no park connections - just good old fashioned camping in the mountains.

Thanks in advance for your thoughts and suggestions!

5 Replies

  • Chris_Bryant's avatar
    Chris_Bryant
    Explorer II
    Oct 06, 2019
    Onan RV generators don’t charge the starting battery, so the batteries need to be identical and parallel.
  • wopachop's avatar
    wopachop
    Explorer
    Oct 06, 2019
    I've never seen a toy hauler with a separate generator starting battery. Worse case scenario you jumpstart the genny using your truck.
  • CA_Traveler's avatar
    CA_Traveler
    Explorer III
    Oct 06, 2019
    Do a energy audit or otherwise determine if one battery is adequate for boon docking or even 2 batteries along with gen run time. If they are the same connect them in parallel and see what happens. But carry jumper cables and perhaps a battery pack.

    There are options for larger batteries including deep cycle batteries. Everything can tie together including your charger and it's capabilities in terms of charge time/gen run time.
  • prichardson's avatar
    prichardson
    Explorer
    Oct 06, 2019
    One battery should for generator starting only and should be a starting duty battery. The house battery(s) should be deep cycle with the total AH rating depending upon how much time you want to spend on battery vs generator.
  • enblethen's avatar
    enblethen
    Nomad
    Oct 06, 2019
    Verify that both batteries are the same. If so they should be connected in parallel. It is possible that the genset installer put a smaller battery in for just it.
    Be cautious able running batteries down to the point genset cannot be started. We carry a battery pack for low or dead battery! About $40, Harbor Freight

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