what gauge wire between two batteries?

raztec wrote:
I'm only using it to run the fan, charge my computer and electronics primarily.
In the winter, the furnace will be running on occasion.
And I may run an external water pump to fill my tank.

But no t.v, a/c or microwave for sure.

Thanks
R

Not an electrician or engineer but IMHO the wire between the two batteries only needs to be up sized from the heaviest use going out.

You are not using it to start the engine in the car? so the electric between the two should be equal two the largest amount going out.

Or just measure the distance and run down to the auto parts store and buy the heavy cable???

Really not that big a deal.

JMHO