A couple of my bracket racing buddies batteries would run down when hot lapping. Both had 1 wire alternators that did not keep up for whatever reason. I finally convinced them to ditch the one wire and go to a 3 wire voltage sensing gm unit. They were reluctant so I bought a cheap EBAY 105 amp alternator to show them how well it would work. I measured 25 amp draw with their cars off, water pump, fans, fuel pump, ect on. Then I measured the output of the alternator at idle in gear, the little chinese alternator was putting out 40 amps at 1200 rpm in gear. Could not believe it even though they claimed as much in the ebay add. We figured the cheap ebay special would burn up soon enough, but they never did. Been on the cars for 3 seasons.

They are even cheaper now! : ebay alternator

Charlie