Camper battery bank wiring.

First there are a few rules of thumb to follow when wiring a battery bank.
1) Use wiring that is as large as you can afford, smaller wiring means power loss.
2) Keep your wiring from battery to battery the same length this will help insure proper charging.
3) You can use heavy weight welding cable between batteries it is more bendable.
4) Put in a battery cut off switch between the batteries and the RV
5) Use the same types of batteries and of the same age.

When I did my battery bank I bought a cable clamp tool and did my own and I also spent more and installed the larger 1/0 cable for the most power flow, that alone was $60.

You will have to decide on a 12 volt setup of 2 or more battery's or a 6 volt system of 2,4 or 6 batteries.

First the easiest system the 12 volt, you will want to use a Parallel wiring setup and you can even do a 3 battery system. Below are a couple of diagrams to follow. This will keep your system at 12 volts and if you are using say 150 ah battery's you would have a 300 ah system for 2 battery's or 450 ah for 3 battery's.
Remember to use batteries that are all the same type and age as they will charge more equally that way.

6 Volt systems
If you are using a small bank of 2 battery's you will want to go with Series wired setup follow the chart from Trojan below. This will give you 12 volts and your battery ah output will stay the same.

For a larger system you will want to go with Series/Parallel wiring, this will give you 12 volts and double your ah output so if you are using 232 ah battery's like I did then for 4 you would have 464 ah capacity.
Follow these charts below.