Wiring Trailer for Two Batteries, Breakaway Battery and Auxiliary Battery

Updated 09/18/2017 | Published 09/17/2017

Question:

Im trying to run power to an auxiliary battery for lights in my enclosed trailer. With the current configuration, my seven way runs to a rechargeable battery for the breakaway line. When I tried to tie into that same 12 V feed from the seven way that powers the breakaway battery, when I hook up the ground wire to the trailer for the new aux battery, It arcs on the auxiliary battery terminal. What am I doing wrong. I really dont want to unhook the wire for the break away battery, which some people have suggested.

asked by: Roger F

Helpful Expert Reply:

Typically people will let the breakaway battery run the breakaway system and then would use the accessory battery to power the interior lights etc. This tends to work the best since your breakaway battery needs to always be charged and interior lights could potentially drain the battery of the trailer.

Since when you charge two batteries on the same circuit you have the potential to end up draining both the solution is to install a diode on the circuit to prevent this like the part # RM-690.

I attached a diagram that shows how this would be done.

expert reply by: Jameson C