Wiring Batteries

Wiring Batteries

by Brandon (NY)

Question: A little new to the travel trailer scene. I have a 29 ft. 2008 Keystone Hornet 26BH. My wife and I do a lot of dry camping at state campgrounds and really enjoy our trailer. However, at the current time we don’t have the funds for a good, quiet generator, but are saving for a nice quiet inverter and generator.

Anyhow, because of this I recently wired a second 12 volt deep cell marine battery in parallel with the deep cell battery that came with our trailer. I have the trailer plugged into our house by way of 200ft extension cord.

I wired it and had it unplugged and the battery meter on the trailer didn’t register a charge. It has been plugged in for a little over 24 hours and when I checked I had just wired the second battery. Is this a wiring problem or a battery problem or am I missing something? Any help is good help. Thanks.


There are several things that come to mind in trying to help you diagnose the charging problem.

Let’s start with the correct way to connect a charger to the 2 batteries you connect in parallel. Here is a link that shows how to connect a charger for your specific configuration: http://www.batterytender.com/Connecting-Chargers/. Go to #9 that shows 2 batteries in parallel being charged by a single charger. If you are not connected as shown then you need to correct the wiring.

Other things to check:

  • Have you verified that the fuse or breaker for the on board charger is good?
  • Have you checked all your battery connections to make sure they are good and tight and there is no corrosion?
  • If everything is connected correctly and the charger is good then it is time to look at your extension cord. We suspect that your 200 ft. extension cord could be the problem, unless your extension is 10 gauge or better. With such a long run you may be losing too much amperage due to resistance.

We hope this has helped. Please let us know what the outcome is, as we are very interested in your attempt to extend you dry camping capability.

Other comments welcome.

Comments for Wiring Batteries

Click here to add your own comments

Aug 29, 2012

Circuit Breaker

by: B-NY

Okay so after camping for the weekend back in the beginning of August, I found the cause was not the cord at all, but rather, the circuit breaker on the outside of of the TT. So I replaced this and got a deep cycle battery and essentially had no further problems…Just wanted to give you guys a heads up. Thanks

Aug 08, 2012

Seems to be the cord

by: B-NY

It appears that the cord would be the issue. I have the trailer plugged into the cord – it appears that it can run the light, but not much else. So it seems to me, as you suggested, the power coming that far on a series of extension cords has lowered the available watts to power things and isn’t charging the batteries.

I will run the generator that I do have (FrankenGenerator = Very loud) to see how that recharges them. Furthermore, I will be off to go camping tomorrow and will be driving about 2 hours or so which should charge them pretty good as well. Thanks for the help – much appreciated.

Click here to add your own comments

Return to RV FAQ.

/* ]]> */