What size cable betwee 6V batteries?

DrewE wrote:

B.O. Plenty wrote:
I used some #4 that I cut from a pair of jumper cables. Made my own lengths and the cost was much lower than buying them.

B.O.

If it's working well and safely for you, I don't want to suggest you change stuff.

But, in general, it's worth noting that nearly all jumper cables these days are made using copper clad aluminum wire, and so the current carrying capacity is not equal to that of the same gauge of copper wire.

Mine were all copper. I used copper terminals as well. Just used it for thr short cables that connect the 6 volt batteries to each other. The rest are 2 gauge that I already had.