Trailer wiring help

[iam_canadian22]

Hey guys this is more geared towards my trailer then the truck but hopefully somebody can help. Ive got an 18' car flat deck car hauler and i wanna mount a winch to it. Ive got a tool box that ill be putting the battery in. Question is how do i go about hooking up this battery so it carges from the aux wire from trailer wiring. Trailer already has a small battery on it for the break away trailer brakes. Can i just go from it? Or remove that one and transfer wiring to the larger battery? Other option?

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[Rampant]

Winches draw a lot of current from the battery. The current provided by the 7-pin will maintain a charged battery if using the lights while pulling, but that's about it. It's not meant for high amperage draws.

You're going to need a 120v converter/charger to get that battery charged back up properly after using your winch. I have this 60 Amp unit from Progressive Dynamics in my enclosed car hauler and it works very well. I also hook up an inverter generator while using the winch if I'm pulling something heavy and I'm not near a plugin. I have a small solar panel hooked up to it when not in use.

Here is some great info talking about a situation similar to yours.

 

[PaulTGarrett]

I have the same trailer setup and agree with Rampant's answer but I do the same thing a bit differently. First off, I keep the breakaway battery and my winch battery charged through the 7-pin while drving. I come off the charge connector to a dual battery isolator and feed each leg to each battery. I don't remember the part number but I bought it off of eTrailer.

Once I get to the point of dragging something up onto the trailer, I unhook the 7-pin (to keep from blowing fuses) and connect the winch/battery up to a winch "rear bumper power kit" that I had a local 4x4 shop build and install. Basically two #2 welding cables coming from the vehicle's battery connections going through a 150 amp breaker back to the rear bumper. The cables terminate to an Anderson 300-amp power pole connector.

Any of the big winch manufacturers make the rear bumper wiring harness. You could look them up and buy one from them. I just have friends at the 4x4 shop and built my harness cheaper than a manufactured one.

I set the engine on fast idle, winch the load up on the trailer, then unplug the Anderson and re-plug the 7-pin. Nothing external to the truck/trailer needed, no 12-volt to 120-volt to 12-volt conversions/converters/chargers needed. You have a good alternator on your truck. Use what you have!

Oh, and I -occasionally- will pull up a car on my trailer. Usually it's shipping containers full of TV tower "stuff".