Electrical: Generator brush life?

[Ron Dame]

My Prestolite generator just quit.. actually it wasn't instant, and in fact the GEN light stays off, though the light works. Still, I'm not getting output from the generator. It has only about25,000 miles on it since a rebuild, including turning the armature, new bearings, etc.

It's been many years since I dealt with generators, could it be the brushes are worn already? What is the life expectancy of brushes?

[greyben]

I'm sure there are a lot of variables involved, but in my experience about 100,000 miles or more.

[Ron Dame]

I'm sure there are a lot of variables involved, but in my experience about 100,000 miles or more.

I was guessing 50K or so, but certainly not as few as 25K. Guess I'll pull it tomorrow and haul it over the the auto starter/generator shop, see what's wrong. BTW, I measured at the generator, the battery, and the regulator. I wonder why the light did not come on?

[christophe]

I often saw reconditioned generators with brushes that fit, dimensionally speaking, but were not of the required quality. This, or stronger brushes springs might explain the problem. I usually don't open a generator until 100 000 km unless for greasing.

[jclary]

I often saw reconditioned generators with brushes that fit, dimensionally speaking, but were not of the required quality. This, or stronger brushes springs might explain the problem. I usually don't open a generator until 100 000 km unless for greasing.

Christophe might be on to something regarding Brush "Springs." Before you go through a lot of trouble, take the dust cover off the generator. Perhaps the brush has become hung up and not advanced as it should with spring tension. I have had that happen before. The clearance is so small, you might not even notice it when you press down on them. Depending on how good your low back is when bending over a fender (mine is not too reliable these days), and if you have a good inspection light, you might be able to make the check and not have to remove the generator from the vehicle. Let us know what you find.

[Ron Dame]

Brushes are good and riding on the commutator.
Here's a question for you electrical guys: I think this may have started when I installed the power steering on the truck, and the generator had to come out. While I labeled the wires, I did not label the generator, and there are no marks on it indicating field and armature. What would happen if I had these reversed? Could that also be why the GEN light never came on except when the engine wasn't running?

[rstrasser]

Ron;
Are not the armature and field wires of a different size as are the two terminals. I would think that if you reversed the wires on the generator you would have let the smoke out of the system. I never tried it so I don't know for sure. The wire size inside the regulator are also a different size.

Ron

[Ron Dame]

The wires are different gauges, but the lugs are the same. That said, I am pretty sure I have them right, simply by the memory in the wires and where they want to go. The Genny is going to 'the guy' for a check-out tomorrow, I just did not want to be embarrassed by finding out I hooked it up wrong.

Ron;
Are not the armature and field wires of a different size as are the two terminals. I would think that if you reversed the wires on the generator you would have let the smoke out of the system. I never tried it so I don't know for sure. The wire size inside the regulator are also a different size.

Ron

[RadioRoy]

Often the Armature stud will have an "A" stamped into the case. That's the fat wire. The skinny wire is the field. If you did hook it up wrong, you might want to inspect the regulator.

Do you know how to test the generator on the car? With the engine running:
-ground the field terminal and look at the ammeter while revving the engine
-don't shut off the engine with the wire grounded

[christophe]

It is always recommanded to polarize the generator after disconnecting and reconnecting generator-regulator leads. I think you should try this first. Here is what says the shop manual about it.

[JoeHall]

A good friend of my dad's, back in the 1960s, ran an auto electrics repair shop; main business was starters and generators, and business was always booming. So it was common for them to fail. I have had them fail in way less than 50,000 miles. Even had the rear bushing work its way out and disappear; the generator kept charging, and it just made a rattling noise.

Just another reason I went to 1-wire GM alternators many years ago. Even if it fails, just set it on the counter at the nearest FLAPS and exchange for another one. AutoZone has a lifetime warranty on their DuraGold line, and I have exchanged couple of alternators, at no charge. SO they are not bullet proof either, but sure easier to find and swap out on the road.

[az64stude]

Very strange, the AMP light goes out when running (thats correct). You may want to leave wires alone. Try running engine and disconnect battery terminal (NEG.) if the the engine still runs then you know the charging system is working correctly. If not, then check wires and don't overlook battery and voltage regulator. Good Luck

[Ron Dame]

Very strange, the AMP light goes out when running (thats correct). You may want to leave wires alone. Try running engine and disconnect battery terminal (NEG.) if the the engine still runs then you know the charging system is working correctly. If not, then check wires and don't overlook battery and voltage regulator. Good Luck

Just got a call, the generator is fine, but the regulator is shot. Boy have those gotten expensive! His best price is $111 plus shipping, and all the FLAPS seem to be there too, if they even list one!

I wanted to go to Bob Johnstone's tech tips site and see about putting a solid state regulator in the old can, but the page seems to be gone. Anyone know where it moved to?

[Skip Lackie]

Just got a call, the generator is fine, but the regulator is shot. Boy have those gotten expensive! His best price is $111 plus shipping, and all the FLAPS seem to be there too, if they even list one!

I wanted to go to Bob Johnstone's tech tips site and see about putting a solid state regulator in the old can, but the page seems to be gone. Anyone know where it moved to?

http://www.studebaker-info.org/

[rstrasser]

I don't know if anyone makes a electronic regulator for a Generator.
Bob's Page is http://www.studebaker-info.org/
As for shorting the field terminal. Works with Delco Generators and some Autolite and Prestolite. Other Autolite and Prestolite generators need the field terminal powered to produce a output.
Also Prestolite Alternators need their field terminal powered to test for output.
Ron