I have two battery compartments in my 5th wheel. However, only one has the batter connections coming from it. An I simply add the second batter and connect to the same posts that my other batter are connected to? I can by the cables from Napa in any length that I want.I am just concerned that by adding a second batter that I will end up with 24 volts vs. 12 volts.I have a 2017 Heartland Bighorn 3575EL.Thanks for the help.-John

Hook two 12v batteries in parallel (doubles capacity but not voltage) by hooking positive to positive and negative to negative (reds together, and blacks together).

Just be sure I am clear, as I not very bright when it comes to DC.I can take the red wire from the second battery and attach it to the same place the red wire from the first battery is attached to the 5th wheel?And the black also, correct?Thank you,-John

So just a further thought, how would they have to be connected to have 24 volts? I don't want 24 volts, I just want to ensure I don't do it incorrectly.Again, thanks a lot.-John

Yes. As long as you connect plus to plus and minus to minus all is good. Depending on how long your connecting cables need to be you can buy welding cable which is very flexible and have ends put on them. They will carry way more current than you will ever need, but sometimes ease of handling is worth it.

2-12’s you’ll want to connect in parallel

Dual Battery in my 5th wheel. | Good Sam Community

Dennis_M_M
Explorer
May 28, 2018
Spend some time reading The 12 Volt Side of Life

It will answer all of your questions and provide a lot of info that will make your RV life a lot easier!
padredw
Nomad
May 28, 2018
Dennis wrote:
Spend some time reading The 12 Volt Side of Life

It will answer all of your questions and provide a lot of info that will make your RV life a lot easier!

Good advice. This web site has been my tutor and friend for years.
ChuckSteed
Explorer
May 28, 2018
Buy the shortest auto style cables needed for interconnecting your two batteries in parallel.

#6 gauge would work but the larger diameter auto style battery cable will have less resisntsce and the transfer of current will be better...

Also during charge states the batteries will charge more equally with that larger connect cable
Njmurvin
Explorer
May 28, 2018
Regardless of which (12v parallel or 6v series) system you pick, it is recommended to start out with new, mathching batteries. I don't have room for 6v batteries. So, I went with 2 x 12v Interstate marine batteries from Costco and I'm very satisfied. A solar charging system to keep them maintained is a good idea as well.
prelucir
Explorer
May 28, 2018
Thanks everyone. The reason I was interested in adding another batter is: mine went dead and I had to purchase a new one so that I could move my 5th wheel. I now have charged the original and it is holding a charge so I thought I would put both in. They are both deep cycle marine batteries. One is Duralast and the other is Interstate. I am sure they will work together.

Thanks for all the help.

-John

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Dual Battery in my 5th wheel.

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