Type of cables to use for connecting 6v batteries?

marquette wrote:
Do you mean that to keep all the cables the same length you have to pick the longest cable run and then buy all cables at that length? So for a short run you will have cable rolled up inside the battery box because it is too long. Or did I miss something?

Nope. The interconnection cables between batteries should be as short as possible.

The cable sizes will depend on the distance between the inverter and the batteries. Don Rowe has a pretty good FAQ section about inverters.