One of our trailers is an Interstate Cargo trailer. I need to install a battery inside the trailer so we can have interior lights when the truck is not hooked up to the trailer. I want to wire it such that the truck will re-charge the battery when in tow. fyi...Currenty, you have to have the key ON in the truck to run the interior lights in the trailer. it does not matter if the truck's running lights are on or not. I hope that helps explain the current wiring situation. appreciate any advice on how to wire this up correctly. thanks.
im pretty sure you just have to run a hot wire from your plug to the battery. you already have a power supply in your traler plug. splice into that to your battery. that way the battery is charging while hooked to the truck and you will have a power source for your lights when its unhooked from the truck. you will also have to run a ground cable from the battery to the chassis. that should do it.
I would reccommend getting a battery isolator for the truck like the motorhomes use so it doesn't drain the trucks battery and install a deep cycle battery in the trailer.
The center wire on the 7 way plug is an aux wire, and should have power already. So all you would need to do is install your battery, wire your light to it, and hook up to the trailer. I would agree though if it pulls power from the truck when the truck is shut off you may want to put an isolator on it. Not sure if it will or not.
