Another wiring question

[Nmurphp]

So as you can see from the picture the previous owner had a custom wiring harness made by a bear or a bored 10 year old. I have already purchased a junction box and 7 way wiring. my question: I don't see a black wire for 12volt from car to trailer. Am i right to assume the black 12v wire from vehicle goes directly to the positive side of the battery?

[mainah]

If you are starting from scratch with a new harness it should be black and a larger gauge than the others coming from the TV yes it can be connected to the battery I would fuse it at 30 amps. The wire going to you converter/charger maybe be red it will be a #8 wire so it will be heaver than the others also it too should be fused at 30 amps.