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Flinx777's avatar
Flinx777
Explorer
Aug 08, 2016

How to connect RV batteries together

I purchased a used RV (5th wheel) that has only 1 battery. I just replaced the battery and decided to purchase an additional battery so I can put them in parallel (or is the term series?). What I'm attempting to do is have 2 batteries running the house lights/landing gears. My last 5th wheel had 2 batteries and it was a good setup.

So, I went to autozone and bought the cables to connect the 2 batteries. Does anyone have a diagram or a recommendation on how I now setup the batteries to connect together? My assumption is that I connect the 2 batteries by connecting their negative posts together and the positive posts together. Then I'm assuming I connect 1 cable going to the RV on 1 battery and the other cable on the other battery. Again, this is my assumption but before I hook anything up, just want to double check. Also which cable running to the RV do I connect first? The positive or negative? Sorry if this is an elementary question but don't want to connect anything up and risk burning up the electronics in my RV.

In case the RV information is needed, it's a 2004 keystone sydney outback 5th wheel bunkhouse.

29 Replies

  • You might want to make sure your RV isn't plugged into your truck before you start the battery wiring. You could blow a fuse on the charge line.
  • Add a 4th to connect the negative last and disconnect it first.
  • K Charles wrote:
    pianotuna wrote:
    Always connect the negative cable first.

    Never connect the neg first.

    The joys of forums...one says to do one thing, 3 say don't. Guess I'll side with the majority on this?
  • pianotuna wrote:
    Always connect the negative cable first.

    Never connect the neg first.
  • Community Alumni's avatar
    Community Alumni
    pianotuna wrote:
    Always connect the negative cable first.

    I beg to differ, positive first when connecting and negative first when disconnecting. Same as when you boost a battery; there is less chance of shorting out the battery/system by touching something accidently.
  • downtheroad wrote:
    The image shows how to connect the batteries in a balanced manner. But the top "Equal length cables" is INCORRECT as those cables do not need to be the same length. The other 2 cables need to be the same length and size for a balanced connection.
  • your question WAS the smart thing to do,ASK ,the drawing is perfect. if you,d have screwed things up, you could have been on the 6pm news. always ask , thats how we learn, happy camping.