Just a point of correction about car alternators.
They are three-phase, full-wave rectified alternators, producing six voltage peaks per revolution. None of the six half-waves are “discarded.”
None of the six half-waves are “discarded.”
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You’re referring to the output to the bus/battery... the regulator IS discarding the other half of those “half waves” you speak of ,, if not they would be full (AC) waves,, and yes you’re paying in gas/diesel to generate the half of the wave that is discarded. If you don’t believe me wait until you have an alternator with a blown diode and then measure the output, it is AC not DC.