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I'm speaking from a theoretical standpoint only here - not from much voltage regulator experience and definatly not from experience with TO-20 regulators... But, I think in most old regulators, there are three relays - cutout relay, voltage regulator relay, and current regulator relay. The cutout relay prevents the battery from discharging through the generator when the generator is not generating. The voltage relay is supposed to protect the battery and other components against over voltage from the generator. When the voltage gets too high, the relay opens and charging stops momentarily. The current relay provides over current protection to the generator during high current loads. When the charge current gets too high, the relay opens and sends the current through a series coil winding (basically a big power resistor) which slows down charging current. Now here's my theory: There is a higher charge load than 12 amps in the system. At low RPMs, the generator is not generating enough current for the current regulator to kick in so you see the 12 amps. At high RPMs, more current is provided to the charge circuit, the current relay kicks in and redirects the charge through the series coil which limits the current down to about half an amp. In other words, I think there is a problem somewhere else in the system (lights, battery, ignition coil, shorted wiring, etc.) that is trying to draw too much current and the current regulator is just doing its job of regulating the current. Don't know how you could prove this... Can you open up the regulator and watch the current relay open up as you speed up the RPMs? Or measure voltage accross the series coil and watch for a change from 0V to 6V as you idle up? Mike
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