Adding a Trailer Battery to an Enclosed Cargo Trailer

Question:

I am redoing a 21 ft enclosed cargo trailer. I am rewiring 120 volt and 12 volt system. I am trying to figure what I need so that when my trailer is unhooked from vehicle I can still use the 12 volt lights etc what do I need to do this from the new junction box I am getting your part 38656 to the battery I will be installing inside the trailer so I can use with or without tow vehicle. I am ready to place my order for all that I need except for that, can you help or tseer to some one who can.Thank you.

asked by: Mike

Helpful Expert Reply:

Start with mounting a battery. Since the trailer is enclosed, it would be a good idea to mount it on the trailer frame using a battery box like # 329-HM318BKS. Next, you will need to have the right kind of connectors on the truck and trailer. I would use a 7-Way RV style if you do not already have them on the truck and trailer.

There is a 12 volt circuit on a 7-Way. You can run a wire from the 12 volt circuit on the trailer side connector to the positive battery terminal. The battery should be grounded to the trailer frame. The 12 volt hot lead will maintain the trailer battery, though it will not be able to fully charge it.

With the battery installed, you will want to wire the lights to it. The lights will have a power wire and a ground. The power wires for the lights is currently connected to the 12 volt circuit from the trailer connector. You will need to instead route the trailer light power wires to a switch, like # BL0108-00, using a spade terminal. Using another spade terminal, connect a length of wire to the positive battery terminal. Hit the switch and the lights will turn on, running off of the trailer battery.

expert reply by: Jameson C