Generator charges for 5 seconds

[Chris Van]

Hi Boffins

Please help. My A is my only car (daily driver) and for some reason the genny has stopped charging.

I thought it was the cutout switch so I put a new one in (diode) but still no charge.

So I took the genny out and cleaned everything nicely including the commutator and put in a set of new brushes, first filing the new brushes to make sure they fit nice and flush on the commutator.

Then I put it back and started the car and it only charged for 5 seconds then the ammeter went back to zero.

It is extremely painful to have to charge my battery manually every night and I have noticed a deterioration in the condition of the battery from its being abused like this.

Any ideas? Am at my wits' end.

Thanks a billion.

[Tom Wesenberg]

I've never heard of filing the brushes. The normal way is to put a strip of sandpaper against the commutator and twist the armature and sandpaper back and forth a few times. This will quickly sand the curve into the brush end.

Do the brushes move freely? How were the wires inside the generator?

Look at the ammeter terminals for a loose nut. Look at the terminal box for loose terminals or corroded terminals.

[H. L. Chauvin]

Hi Chris,

Filing generator brushes was recommended by Ford in his Model T Manual, but I never found it beneficial and never did it.

Your problem could be your individual insulated and isolated segments of your commutator have worn brush/commutator material and dirt in the grooves thus not allowing the commutator segments to be insulated from each other.

Cleaning out all of these approximately 1-1/2" long groove to a depth of about 0.010" may help.

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Just one way used successfully for over 50 years:

Ford recommended using a fine wire to clean grooves in his Model T Manual; however, I was shown to always used a fine tooth hacksaw blade for cleaning commutator grooves.

Remove the waves from the hacksaw blade either on a grinding wheel, or with a hammer on an anvil where the hacksaw blade teeth straight all along the blade and are aligned with the top of the blade.

Very carefully clean out each individual segment.

Final test is hit the generator for a mili-second with 6 volts -- if it won't turn like a starter, it will not generate electricity.

Always worked for me -- hope this helps.

[Patrick L.]

You didn't mention the polarity or voltage. The diode cutouts are polarity sensitive.

You might try applying power to the generator and seeing if it motors [ loosen belt]. If it motors it should [usually] be fine.

You might want to try to polarize/flash it.

[Chris Van]

Thanks guys

Unfortunately nothing works. I have sent the genny in to a sparky and will let you know the outcome.

I was so hoping the commutator gap cleaning would work but the thing is dead as a doornail.

[H. L. Chauvin]

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Hi Chris,

We are all wishing it is something very simple and inexpensive for you ...... a new armature plus re-build is not wallet friendly all of the time.

We look forward for your report ..... it will be educational no matter what ..... an after action report helps everyone.

Thanks for the very kind reply.

[Mitch//pa]

... I always use an external volt / amp meter when doing any work on a charging system, doesn't matter of year make or model..

[Chris Van]

Hi H.L., Mitch, Patrick, and Tom

The plot thickens and is not looking pretty. The sparky said my armature was burnt out. In the interests of saving time I fitted an (early) A generator lent to me by a friend but this thing charges like a herd of buffalo. With the new brushes, the ammeter goes off the charts. Even with the headlights on when I start driving the ammeter goes right off the charts. It still the original ammeter and has never done this before. Does anybody know why this is so? Interestingly, this spare generator had a brush missing - did somebody maybe remove a brush to make it put out fewer amps? By the way the sparky tested it and said it is putting out 6.5 Volts but could not say why it is pushing out enough amps to turn the dynamos of the Hoover Dam. Any help or comments would be invaluable. In the mean time I have disconnected it because I don't want to damage my brand new $100 6 volt battery. I have also tried two different cut-out switches but neither seems to make any difference.

[Mike V. Florida]

Originally Posted by Chris Van

With the new brushes, the ammeter goes off the charts. Even with the headlights on when I start driving the ammeter goes right off the charts.
I have also tried two different cut-out switches but neither seems to make any difference.

Cut outs only stops battery voltage from getting in to the generator.

As for your "ammeter goes right off the charts" you have a short somewhere in the wiring, your battery is in backwards, or the generator is charging backwards.

[Tom Wesenberg]

Are you saying this is a 5 brush powerhouse generator?
This has 2 ground brushes, 2 power out brushes, and 1 adjustable field brush.
You can remove one ground brush and one power out brush and still have output.
Have you adjusted the field brush? Move it up to lower the output. That is move the brush the opposite direction the armature turns, to lower the output.

[Bob C]

Can you post a picture of the generator?

Bob

[Chris Van]

Hi Bob, Tom, Mike, Mitch, HL, Patrick.

Apologies for the tardy reply. The problem as it turned out was a bad sparky who misdiagnozed everything. I found a proper boffin sparky and he took one look at the parts of my genny and said that there is nothing wrong with the armature... except that the shaft is worn... and thus the armature had been scraping against one of the 2 field coils and damaged it. So he built up the armature shaft and turned it back to size, and rewound the damaged field coil, put in a new set of brushes and new front bearing and voila! for $50 my genny is good as new and is charging like a dream. As for the other genny... the bloody thing was 12 volts! So thank the Lord I didn't damage my expensive new battery but fortunately when I drove to the proper sparky in the middle of Johannesburg it was raining cats and dogs so had to have my wiper on and lights and interior light so that used up a lot of the power of the frigging 12 volt generator.

So a happy ending and my A is back on the road and this morning in light fog I could even drive with my headlights on and it felt fantastic.

Guys, thanks so much for your help, and I hope my little story helps too.

Happy motoring and regards from South Africa.

Chris Van