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Old 06-29-2020, 10:59 PM   #44
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Join Date: May 2010
Location: Young Harris, GA
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Default Re: 29 Tudor charging system question

Originally Posted by fred93 View Post

I finished rebuilding the generator. I also installed the old ammeter that was in the car when I started the restoration (I swapped the bezels so the old ammeter looks new--it works okay)

The generator puts out 6 amps at fast idle with 7.5 volts steady!

Two questions though--

#1--I hear a whining noise coming from the generator at high idle. If I take a plastic stick and touch the 3rd brush the whine goes away. I am thinking that maybe that whine will go away when the brush seats in???

#2--When I turn on the headlights the dash ammeter reads negative 6 amps. I assume if the generator is only putting out 6 amps that when the headlights are turned on a discharge reading would be normal. I guess if the car is going to be driven a lot at night I would need to adjust the 3rd brush. Seems like a PITA to me!
#1 - correct. If the noise does not go away in a few days, look at the way you have the brushes installed. You may have one at an angle that is hitting the rotating copper bits on the shaft, making the buzz.

#2 - correct. The generator puts out a constant current, regardless of how much you actually need. A crude, but effective, design. Ford had car owners bring their cars in for service often and adjusting the generator charge rate for the season and type of use the car saw was part of the service.

Your 6 amp charge rate is adequate for a car that has a battery minder connected up to it while it is parked in a garage between uses. Then you are always going out with a fully charged battery. You can run at night for a few hours without killing the battery if you need to.

This PITA of adjusting the 3rd brush is why so many people install a hidden voltage regulator on the original generators. Then you get the current you need when you need it but less at other times, after the battery is charged.

As many of you know, I am not a big proponent of "modern upgrades" on the Model A because they often create more problems than they cure. To me, the voltage regulator is one exception. They really do help keep your battery charged without boiling the water out of it. They get you more current for lights when you need it. Worth installing.

Jim Cannon
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