I used a 100-amp single-wire internally regulated alternator I found super cheap in an overstock clearance bin. It doesn't actually charge the system at idle, the initiating circuit fires halfway to the red-line. This was not a problem when I ran the old highways twice a week, but since its retirement from regular highway use I've had to use a solar charger to keep the battery topped up. Pay attention to the self-exciter's initiation point compared to your engine's effective RPM range to avoid my error.
