low voltage at coil

when key is in start position you get full voltage (bypasses the ballast resistor) and when you let the key go after it starts, in the run position, you get half voltage.

the purpose for this is that the coils last longer, they were designed for the lower voltage. if you run them at 12v all the time it makes them burn up quick. when starting the car, having extra voltage helps the car start easier.

someone else can come chime in with the exact voltages for you.