How to Wire Two 12 Volt Batteries on a Trailer

Question:

Ive added a 2nd 12v to my 16foot Bambi. When connecting as shown, the neg RV cable is stretched to the far battery. Q: Would connecting both RV cables +and - to the near battery and bridging to the far battery be a bad idea?

asked by: Thor

Expert Reply:

It sounds like you tried to attach a picture but it didn't come through. However, I think I've got the idea.

If I'm correct, what you're trying to do is actually considered the ideal way to connect two trailer batteries. Generally the two batteries are connected in parallel. Meaning the power wire is ran to the positive side of one battery (From the trailer's 7-way connector) and that same battery is grounded to the trailer's frame. Then both the positive and negative are ran from the first battery to the second, and the output will then run from the second battery's positive to whatever accessory you are using your batteries for.

I've attached a diagram that may be helpful for you, but I'm pretty sure you're on the right track already.

expert reply by: Charles S