I would like to add a couple of switched interior lights to my 2 horse trailer. I'm wondering where to hook them in my junction box. I assume the black, always hot wire. I was also wondering, if I add a battery to the trailer, is that the source that would charge the battery?

 

Simply put, yes to both your questions. Provided you are using your seven pin and your truck has the fuses and relays in place for towing, you should be good to go with no problem.

Steve

 

Yep, the 2 Maxi fuses and the two relays are there. Time to go shopping then.

 

Charging the battery from the truck (black wire) will take a VERY long time. Consider having a decent electric charger to speed up the process. Suggest an RV/boat battery instead of a car battery. A few times discharging a car battery will GREATLY shorten it's life whereas a deep discharge battery is meant to be used this way.