B;

Your power and current calculations look OK, but you're quite generous with your wire gauge recommendation...I consider it almost a waste to use 12ga., definately 10ga. for a 10 Amp load...14ga would be perfectly adequite...as a reference, in a home wiring system, a 30 Amp circuit is wired with 12ga., and that is conservative because the wire may be in conduit where it cannot easily shed the heat produced (fatter wire => less resistance => less I squared X R heat).

10ga would be fine for connecting your 60A (maximum) alt output to the battery.

(Still, pretty good for a chemist!...certainly better than I'd do today on a valence equation!)

Cheers