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Hi Everyone

I have a 1953 GMC 9300 converted to 12 volts but still using the generator.
I have been having a problem with it not charging the battery. I have a new voltage regulator and I did the polarization as suggested and checked the voltage at the ARM and BAT terminals of the regulator. I get 12.3 volts at the BAT and .8 volts at the ARM. I also grounded the F terminal and still only get .8 V at the ARM. I guess by this it sounds like my generator has gone for a crap ? Unless anyone else has an idea ?

Does anyone know where to either get another one or get it rebuilt in Ontario Canada ?
Dave

Try checking the field coils for continuity. Remove the back plate of the generator and slip pieces of paper between the brushes and the armature, then use an ohm meter to check the resistance between the "F" terminal and the insulated brush. You should get a reading somewhere around 10-20 Ohms. It's possible a simple change of the carbon brushes will get the generator back into operation without a complete overhaul- - - -with a cost of around $10.00 and an hour or two of labor time.
Jerry

Did you ground the F terminal at the generator or the regulator? If it was at the regulator, you should try again at the generator.

I had a set of brushes lose contact with commutator on the armature while traveling halfway across the country in my '52. I took off the brush cover, reach my finger in and pulled the brush away from the commutator and let it snap back into place. I did this with both brushes and pushed the truck down the hill to start the truck with a dead battery, and it fired right up and the ammeter showed a serious amount of charge. I drove the truck 650 miles to the house.
I am surmising that the brush holder channel got dirty and would not allow the brush springs to push the brushes in as the brushes were worn away as they do over time.

I have seen that too. I think the 12 volt Delco generator does not have the opening with the cover over the brushes, like the 6 volt one does.

I did ground it at the regulator, I will try again at the generator. I will also have a look at the brushes as well. I will do it tomorrow AM and let everyone know.
Thanks for the input everyone

Well, I tried it at the generator with the same results. There is about .8 volts at the generator.

You are correct truckernix, there is no opening or cover on the generator for the brushes. I will wait until off season and remove the generator and have a closer look. As long as the battery is charged it keeps going. The only reason I noticed was that we have been out late enough the past four times to need lights on coming home and I guess the battery finally drained on the way home last time. At least we made it within a couple of hundred feet from my driveway. Just had to go and get another battery to make it home.

If you're not going to fix the problem for a while, at least install a battery maintainer to keep the battery topped off all the time. Cycling a conventional battery below about 60% of its capacity repeatedly dramatically shortens its lifespan.
Jerry

Yes, I have a battery tender on it while it sits there.

Do I dare say.........”perfect time for a one wire alternator upgrade” ???????