YMMV Maybe this is specific to me, but my engine needs a long time to warm up and at idle this alternator seems to actually draw around 3 amps, or worse than nothing. It takes 2000+ rpm to supply the around 15 amps that it takes to run the motor and fuel pumps. I also autocross, so the time at speed is too short to keep a small battery charged. I'm thinking about a custom wind to produce charging voltage at a lower rpm, since I don't need 50 amps. It is a trade-off. A bigger, heavier alternator would do it all, or maybe a jumper battery while the engine warms up would fix my particular problem.