Gauging the wire....

[GREENReactor]

For my forthcoming dual 6V set-up (replacing the original 12V "dual purpose" battery that came with the RV) I'll need to add the "series" wire connection between the two. Would 4-gauge be big enough for that or should I go with 2 gauge?

[corvettekent]

There is no point in going any bigger then your positive and negative wires are, that would be like adding a 2" fire hose to your 5/8" garden hose. Now if you are going to add a big inverter you may need to upgrade all the wire.

[2oldman]

Depends on your use. It doesn't need to be any bigger than the supply wires. The amperage is the same everywhere.

[Chris_Bryant]

Even for a short jumper, you really cannot get too big- I would go with #2, even if the main cables are #4.