ammeter pegs even when battery is fully charged
- Thread starter aviator37
- Start date
Patrick L.
Well-known member
There is no regulation in the Model A charging system. When you say the ammeter pegs, in which direction does it peg ? to the positive or negative ? Does the engine have to be running to make it peg ?
These are questions I think need to be answered first, but, thinking that you mean it pegs full positive then you could start by adjusting the third/movable brush to try and achieve a charge rate of 3-5 amps at a fast idle.
These are questions I think need to be answered first, but, thinking that you mean it pegs full positive then you could start by adjusting the third/movable brush to try and achieve a charge rate of 3-5 amps at a fast idle.
Mitch//pa
BANNED
Correct... just watch out for false digital readings from ignition interference.
Usually the flukes have a smooth button to help with that..
Tom Wesenberg
Well-known member
I never use my digital meter when working on cars. I like the analog meters.
Here's two pictures to show the brush end plates with brushes. Until March 1930, the rear end plate used a ball bearing, then Ford switched to a bushing. Notice in the first picture, the brush on the left is the ground brush, and the brush on the right is the output brush. The thin brush between them is the field power supply brush, called the "third brush". As you move that brush away from the ground brush and toward the output brush on the right, it will be sending more power to the field coils. More power means greater output.
Since your generator is putting out too much amperage now, you want to move the brush towards the ground brush. It may be stuck from years of never being moved, but when you remove the generator band, you can use a screwdriver against the open slot and push the third brush upward to lower the output. Then start the car and see if you have lowered the amps to a safe level.
The third picture shows a cutaway generator that was on display at the Model A Museum at the Gilmore Car Museum in Hickory Corners, Michigan.
Here's two pictures to show the brush end plates with brushes. Until March 1930, the rear end plate used a ball bearing, then Ford switched to a bushing. Notice in the first picture, the brush on the left is the ground brush, and the brush on the right is the output brush. The thin brush between them is the field power supply brush, called the "third brush". As you move that brush away from the ground brush and toward the output brush on the right, it will be sending more power to the field coils. More power means greater output.
Since your generator is putting out too much amperage now, you want to move the brush towards the ground brush. It may be stuck from years of never being moved, but when you remove the generator band, you can use a screwdriver against the open slot and push the third brush upward to lower the output. Then start the car and see if you have lowered the amps to a safe level.
The third picture shows a cutaway generator that was on display at the Model A Museum at the Gilmore Car Museum in Hickory Corners, Michigan.
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Patrick L.
Well-known member
I don't think I'd worry to much about how accurate the ammeter is. Just turn on the lights or step on the brake and see what discharge you have. Depending on the light bulbs you're using the reading will vary, but, still will probably be around 8-10 amps.
Try prying up the third brush as Tom mentioned to see if you can reduce the output to about 5 amps or a bit less.
Try prying up the third brush as Tom mentioned to see if you can reduce the output to about 5 amps or a bit less.
Mike V. Florida
Well-known member
That's one hell of a generator that will still put out 20 amps into a system that has no problems.
Does it move off peg with the car off?
Does it move off peg with the lights on and horn blowing?
Does it move off peg with the car off?
Does it move off peg with the lights on and horn blowing?
Tom F OHIO
Well-known member
If it stays in that position all the time no matter what you turn on then maybe there is a chance that the amp meter is stuck in that spot. Maybe try another amp meter and see what happens.
Patrick L.
Well-known member
It still seems as though you have a simple generator or cutout issue. I'm leaning more towards the generator, but, try and determine if the cutout is an original or aftermarket. The aftermarkets tend to be junk.
Tom Wesenberg
Well-known member
The cutout is simply an OFF-0N switch. On when the generator puts out more than 6 volts, and off when the generator output falls below 6 volts.
One more thing to check is the two wires connected to the adjustable and output brushes. I've seen generator shops mix them up and burn up two generators. The field wire must connect to the adjustable brush, and the output post must be connected to the stationary brush, which is half way around from the ground brush.
One more thing to check is the two wires connected to the adjustable and output brushes. I've seen generator shops mix them up and burn up two generators. The field wire must connect to the adjustable brush, and the output post must be connected to the stationary brush, which is half way around from the ground brush.
msmaron
Well-known member
are you saying your using a generator a NO CUTOUT????