VCCA Home Forums TECHNICAL - GENERAL Electrical - 6 volt Generator Charging on '32

My generator shows about 12 amp charging when I first start the car and then drops back to about 10 amps and never goes to zero or moves from around the 10 amp mark no matter how long I drive the vehicle.

Is this normal or should it go to around zero after awhile. It does go to zero when the headlights are turned on and it drops down when at idle.

Just wondering if it is working correctly.

Thanks,
Jim V.

Hi Jim,
From what you've described,your generator is working O.K.The output of any third brush type of generator is entirely dependent on where you position the third brush.
This adjustment only governs the current output of the generator,and not the voltage.This is why the old headlight globes were rated to work at between 6 - 8 volts,and if the generator was set for night time driving,you would often see a lot of cars driving with their headlights on to use up the extra charge rate going into the battery.
The main electrical characteristic of a third brush generator is,that the faster the armature rotates within the magnetic field produced by the field coils,the more the output tends to drop off.These generators were designed to have a maximum charge rate of around 10-12 amps maximum at a car speed of about 25-30 mph.
For day time driving,depending on the speed you're driving at,a charge rate of 4-6 amps would be fine.If you needed to drive at night,you would have to move the third brush to increase the output to cover the extra load from the headlights.
Hope this is of interest to you.

Thanks Kevin,

That is a good explanation of the generator. I will not worry about it further.

Jim V.

Yep, if it ain't broke ya can't fix it.

Or you could do as many of us have done and fix it until it does break.