The single wire alternator I used on a race car just had a 4 guage wire hooked to the
the battery. The alternator was was self energizing regulator. There are charts on the internet about pully sizes. Proper pulley size is important so it starts charging and does not over spin the alternator.
http://www.powermastermotorsports.co...r_pulleys.html
http://www.powermastermotorsports.co...ternators.html