How can I plug in my Horse trailer into a battery?

Question:

Hello, I would like to be able to use the lights I my horse trailer when it is not plugged into a running truck. Is there a way I can plug the 7 way plug that goes into the truck into a battery? That way I would be able to operate the trailer lights. I would like to avoid running wire through the trailer and just want a simple way to plug it into the battery. Ive attached pictures of my plug for reference.

asked by: Jena T

Expert Reply:

Yes there is a good solution to this. In some trucks even with the key in the off position your 7-way plug on the rear can remain hot allowing you to use anything hooked up to that circuit like your lights. Assuming this is not the case with your tow rig adding your own power wire from the trucks battery to the 1 o'clock pin on your 7-way.

You will use a 40 Amp In-Line Circuit Breaker part # 9510. The copper side will need to be within 18" of you battery and will connect to the positive terminal of your battery using part # 10-1-1 and ring terminals of appropriate size. You then run the same part # 10-1-1 from the silver side of the breaker to the 7-way on the back of your truck securing it along the way properly avoiding sharp edges and sources of heat that may damage it. You will use a ring terminal on the breaker and a Heat Shrink Butt Connector like part # DW05745-5 at the rear where your old 7-way power wire comes out of the plug.

Be sure to secure the old wire properly so it does not make contact with anything that may cause a short.

I have linked a video showing this process but of course you will not be adding the plug.