Sammy77

I am looking to add a battery inside my enclosed trailer for running the interior lights, without having to be hooked up to the truck. I was curious if anything else needs to be added, to protect from over charging the trailer battery? Or if anything is needed, to keep the truck's battery from getting discharged? This trailer is just used for atv and snowmobiles. My truck is a '13 FX4. Thanks for your help.

acadianbob

You will need a 7 pin connector for your truck to charge your trailer battery; and of course a 7 pin from the trailer. One of the pins in the connector is a "hot" wire for battery charging. The truck will not overcharge the battery. There is a relay that needs to be installed in the fuse box under the hood. That relay should have come with your truck. Check the glove box or the console.

bubbabud

If your truck is equipped with the tow pkg then all you need is to wire the new battery to the B+ pin on the 7 way connecter You may have to install the 30amp fuse and relay [supplied with tow pkg in the power dist box] this will power and charge the trailer battery when the ignition is on. If you only need lights when the trailer is connected then just forgo the battery and jump the relay you will have power any time the trailer is plugged in. If the trailer has a breakaway switch and battery then problem solved just use the existing battery.

Sammy77

Thank you both. I have already installed everything in the truck, just need to tap into trailer wiring for the separate battery. I just wanted to be able to walk in the trailer and not kill myself tripping over something.. Lol
I want to be able to power lights without the truck connected.

xcntrk

I think there's still more to it. You likely already have a battery back-up system for the electric brakes which is using the 12v auxiliary pin on the 7-pin system to keep that battery charged. Then your coach lights are tied off that auxiliary circuit too, but somehow isolated from the emergency battery (which is why they don't work when the truck isn't on). So somewhere you need to add coach battery to the system either separate from the emergency brake battery, or replace it with the new coach battery serving as backup.

That's the best I got to help you.

PS: I need to do the same and am watching this thread

Sammy77

Yep. There's more I'd need to do, and unfortunately I don't have the down time to pull the inside walls off the trailer to hide the wiring. It's a snowmobile trailer and season will be here sooner than later. Next year..

Dirttracker18

You should not able to pull walls apart. If this is an enclosed trailer with lights then there is a box mounted somewhere with the power coming in, possibly fuses too. Find that box and mount the new battery near it and tap into the hit circuit. If it is under the floor, drill a hole to run the wires through and grommet the hole. This trailers have a simple electrical system, don't over think this.

Sammy77

Thank you.

There is a junction box attached to the frame, I didn't see anything as far as fuses though. Thanks, I'm going to take a better look at it this week. Any idea what wire I would have to tap into to power my light switch? Or where I could find that info?

bubbabud

If the trailer already has a light and switch pull the switch and see what color wire is used. if the light already works when plugged in and engine on then all you need to do connect to this wire at the junction box. and ground the - side of the battery this will put the added battery in parallel with he system and the breakaway battery[if equipped] it is required in most states if trailer has electric brakes. this will charge both battery's and give you lights when you want them.

Sammy77

Thank you, that's what I was hoping for. If I find that wire in the junction box, I will connect it to the positive side of the battery and I should be able to use the switch then to power the lights off and on.