What is a 1 wire alternator?

It is an alternator that uses a special voltage regulator that doesn't need an ignition wire to activate it. This type alternator only requires a battery wire hooked to it. The voltage regulator contains circuitry that uses the residual magnetism in the alternators fields to determine when to turn the alternator on. The regulator does this by sensing the RPM the alternator is turning, when it gets to a certain rpm the voltage regulator "turns on". This type alternator is commonly used on custom cars & trucks, tractors and other non-standard applications when wiring is a factor.