The 100 position of your 7 way carries this circuit. You would just need to run a length of 10 gauge wire like part 10 1 1 sold by the foot from this pin to the positive terminal of the battery.

Electrical Schematic For Ford Transit Camper Van Conversion
Rv auxiliary battery wiring. You can even combine the different systems like two 6v batteries in series connected parallel to a 12v battery. Then connect the two positive posts together with charger wire secure the clamps and then do the same with the negative posts. To provide power to a winch it must be wired to a vehicle battery or a separate auxiliary battery designated for use with the winch. You can use standard 10 gauge electrical wire but thicker wire will carry more current and give a better charge. You can connect a new 12 volt line directly to the 12 volt batteries in your camper. Therefore it is recommended to use good quality plugs and cables so that the transfer rate efficiency is maximum.
It takes 6 cells connected in series. You can put a maintenance charge on your trailer battery with the 12 volt accessory circuit of the 7 way. A jumper wire is used to connect rv batteries. The negative lead of the trailer is connected to the the negative lead of the first battery. The trailer positive lead should be connected with the first batterys positive terminal. The rv batteries charged with solar panels or additional batteries must allow for minimum loss of power while transferring.
Most common batteries that are used are 6v batteries in series or 12v batteries connected in parallel for more amp hours. All rvs run off of the 12v system. Which is why they are called batteries in the first place. Run two wires from the trailer end of the seven pin connector to the trailer battery. For example a solar panel charging system is often directly connected to the battery for efficient charging. Electric winches require power from a battery source to operate.
Use two different colors of wire such as red and black so you can easily identify positive and negative. Each cell when fully charged will produce close to 25 volts. There are several ways to wire your winch depending on whether your winch is mounted on a vehicle or a trailer the type of winching and the frequency of winching. Connected batteries should have the same voltage and amp rating. An rv battery is a collection of lead acid cells. This is especially useful for circuits that will draw heavy loads or provide charging.
Another set of cables connects the remaining positive and negative terminal to whatever you are connecting the batteries to. To make a 12 volt battery which when fully charge will produce approximately 126 volts. The negative terminal of one battery is connected to the positive terminal of the other battery.