This brings up a VERY important 3 wire install point. The exciter wire. The "one more wire". This wire allows a tell tale dash light if you want that. If you don't, the exciter wire (alternator blade 1) needs to go to a "switched power source". All the instructions keep saying that. "Switched power"....It is true....but..... The ignition switch is the place of choice. Then sometimes folks have "run-on". The motor won't shut off. So everyone panics and says add a bulb, add a diode, a flux capacitor. Well hold on a minute. The feedback, if there is any, is power going backwards up the exciter wire to the coil and keeps the points firing. The term "switched power" means power that is switched on and off. So when the installer attaches the exciter wire to ignition "ON" terminal, they think they are getting switched power. Yes and NO. The ignition "ON" terminal is indeed off when switch is off. But the exciter wire is effectively spliced to the coil wire via using the same terminal for both. The backwards alternator power just bypasses the switch and continues to coil. So when hooking up the exciter wire, hook it to the accessory terminal, which is a switched power. Be sure to verify that it is on when ignition switch is on and off when switch is off. Be sure that there is no other live power wire on ACC terminal.
Using a bulb, just for run-on, supposedly eats the amps/volts so that there is not enough to fire points. Using a diode blocks the backward flow on exciter wire. The ACC terminal method prevents coil from getting voltage when ignition is off. That's the "switched power" that no one explains. I have discussed this before, it's in Stovebolt search.
Remember that the "one wire" is called a self exciting alternator but takes a rev or two to start charging. Go figure. The self is YOU..
The three wire is auto exciting.
Last edited by Rusty Rod; 08/27/2024 1:14 AM. Reason: clarification. unnecessary statements.
