Quote:
Originally Posted by GhostWolfGT
I can't see it making all that much of a difference. I've seen a homemade wind generator spin out of control because there was no load on the alternator being used. .
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Most vehicle alternators red line at 15,000, they can exceed this speed, but not for extended time.
Those small turbine alternators only have to turn a few hundred RPM to make power because of permanent rare earth element magnets. They spin "out of control" at under 2000RPMs because of the huge relatively unbalanced blades attached to them.
You are correct, it does take almost no power to turn an alternator 2,000RPM, but in a vehicle the only time the alternator in a vehicle spins less than 2,000RPM is at idle.
At cruise speed the alternator is typically spinning between 6,000 and 10,000 RPM.
Every time you double the speed, aero dynamic drag on the alt increases by 4 times.
This is why vehicle alternators are not very efficient.