How to Install Battery in Trailer to Power Lights

Question:

I want to add a 12 v battery so I can have a light system and outlet in my utility trailer. The trailer wiring harness has a 7 wire connector. What do I need to build a system that can charge itself from the truck and run while the truck is off? My trailer has interior lights but they haven’t worked in a long time. There is already a small battery box on the trailer but I don’t know if I should just start over new with a new system.

asked by: Tyson

Helpful Expert Reply:

First thing you'll want is a deep cycle battery mounted in your trailer to power the accessories you mentioned. Basically you'll run the power wires from the light system to the positive post and then ground them either to the trailer frame or the negative side of the battery and you'd be set. Now to charge it you'd basically you just need to run a 10 gauge wire like part # 10-1-1 (sold by the foot) to the positive post of the battery as well from the 12 volt accessory circuit on your 7-way trailer wiring connector and when you are towing your tow vehicle will put a maintenance charge on it. The 12 volt circuit of a 7-way is in the 1:00 pin position of the connector.

If this isn't active on your tow vehicle you can take 10 gauge wire and run it from the positive post on the vehicle battery to the matching pin on the connector through a circuit breaker like part # 9510 and you'd be set.

expert reply by: Jameson C