How to Wire a Breakaway Battery and Lights on a Trailer

Updated 07/16/2018 | Published 07/13/2018

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Question:

I have a trailer with a brakeaway kit and I would like to add a battery to the trailer that will be trickle charged by a solar panel. How would I properly hook this up? I have worked on vehicles and understand the grounds but want to know how to introduce a new power supply. I will be using it to power some exterior and interior lights. I have a fuse block for each light that will be hooked to switches. In addition there is a 5v USB plug converter and a 12v socket. Do I run the grounds to the battery or do I ground everything to the frame? Do I ground the battery to the frame or do I leave it floating?

asked by: Rich

Expert Reply:

For starters, a breakaway switch will need to have a separate and independent battery according to most state regulations so it may be beneficial to check with your local DMV or DOT before proceeding. The Hopkins Engager Push-To-Test Trailer Breakaway Kit part # 20099 comes with an independent battery and you can use the 12 volt power on the vehicle's 7-way to charge the battery.

In regards to installing a solar panel and attaching it to an auxiliary battery, the install process is fairly simple but will vary depending on which solar panel you choose. For example, the 2.5-Watt Solar Battery Charger part # PTW2997 comes with both positive and negative leads which are mated to alligator clips. If you were looking for a more permanent install then you could just simply cut off the clips and attach the ground and power directly to the battery with a set of ring terminals.

If the exterior and interior lights would exceed the power draw on the trailer wiring harness then you can install a fuse block or terminal block on the trailer and then run each light to that while attaching the block to the battery for power. The ground wire for each light does not have to be ran to the ground on the battery, just a bare metal surface. The battery will need to be grounded to a bare metal surface on the frame.

I have attached a wiring diagram for a breakaway switch for you but you will need to follow the manufacturer's install instructions for each light/accessory.

expert reply by: Conner L