Trailer brakes & bearings.

Hooking the 12V Battery up to the Aux 12V circuit won't work as Nate pointed out. But there are other ways to keep that battery charged. Travel Trailers do it but you won't have the luxury of an enclosed trailer to protect all the electronics.

Maybe a couple ideas here for you Dave.




BTW: I so want one of those trailers. It's a Featherlite 3110 and you had better be sittin' down if you are pricing one out.

http://www.fthr.com/flatbed-commercial-utility-trailers/model3110-flatbed-trailer/

Even better when said trailer has a wiring fault causing an intermittent open circuit. Plugged it in, took off, all was good. First bump proved me wrong.

Flat blade connectors are RV, They are more common than you think. Most of the new equipment trailers come with them and almost all new pickups come with them. The Tractor-trailer (round pin) connectors and the smaller round (4&6 pin) are actually odd in cases in the rental business.

Found this:
http://rvpowersupply.com/toadcharge.htm

Looks like it might do the trick for you Dave. I might be worried about having a connection between the truck and trailer battery while using the winch, not sure if that would burn out the charger? I would think they have some kind of overload protection built into it.

EDIT: I see now that the specs do indeed mention overload protection from both ends of the harness.