MTFCA Forum

I finished rebuilding my generator and was bench testing it this afternoon. At about 1k RPM I was getting 14.75 volts and about .9 amps, what's did I do wrong. I rebuilt it using the generator rebuilt video on Utube and the Ford Service manual. Any suggestions would be appreciated

what voltage battery are you using for your bench test? also cut out or a regulator?

Check what you did for this https://modeltfordfix.com/adjusting-the ... patterson/

Most people don't look at it that way, but wattage is a bigger concern than voltage.

With that voltage figure, your generator could charge all day at 5 amps or less.

I measured 36 volts when a circuit opened and there was no place for the current to go, so no current.

75 is the maximum possible wattage, but 60 is safer for an older generator.

Your generator is normally putting out 10 amps, when the voltage is 7.5 DC, as measured with a meter with a needle.

When I was checking the generator on the bench I didn't have a battery hooked up, will that make a difference in my readings?

Yes, must have a battery hooked up.

I recommend a fully charged battery be used to check the output amperage. I found that the generator be turned at 1500 ram or more to obtain maximum generator amperage output. Art Mirtes

The Model T Ford third brush regulation type generator is a constant current source.
The correct generator testing speed is 1725 RPM (25 MPH in a typical Model T-remember the generator turns 1.5 times the crankshaft speed). When the brush plate lead is properly (it commonly is not) set at the point of commutation the current output will be based upon the position of the third brush. It is normal for the generator output voltage to be higher than 7.2 volts (the proper cut in voltage of the reverse current cutout).
One of the biggest problems is correctly setting the brush plate lead. It is a trap for logical people and the description of how to do this can be tricky. Try using a 12 volt battery for this (only) setting and it i bit easier. After mastering this setting the rest is easy if you test as I recommend. As for setting the charging rate please read the other generator articles posted on the Model T Ford Fix website. In no case in todays driving conditions should the generator be set at 12 Amps per Ford's recommendation. The generator is capable of producing a 100 Watts of power, continuously operating the generator at high charging higher than necessary and it will destroy itself. The reason for this will become apparent after reading my articles.
Good luck
Ron Patterson

Ron Patterson wrote: ↑

Thu Feb 25, 2021 11:10 am

..... As for setting the charging rate please read the other generator articles posted on the Model T Ford Fix website. In no case in todays driving conditions should the generator be set at 12 Amps per Ford's recommendation. The generator is capable of producing a 100 Watts of power, continuously operating the generator at high charging higher than necessary and it will destroy itself. The reason for this will become apparent after reading my articles.
Good luck
Ron Patterson

This is the link to Ron's reference

TRDxB2 wrote: ↑

Tue Feb 23, 2021 11:51 pm

Check what you did for this https://modeltfordfix.com/adjusting-the ... patterson/