Generator Voltage Adjustment

[Kevro869]

My father and his friend rebuild alternators and starters for a living. They have rebuilt a Model T generator for a customer and it works except for the fact that they cannot get the voltage right. They know to move the "third" brush to adjust the voltage. However the voltage is either too low or so high it stalls the test bench motor.

Thank you in advance...

[redmodelt]

You need to set the whole brush plate to the neutral position. Lift the 3ed brush up and out of contact with the armature. Loosen the 4 screws that lock down the brush holder plate about a turn or just enough to be able to rotate the whole brush plate. Connect 6V's , negative to body and positive to the out put screw. What you are looking for is the generator not to motor anti clock wise nor clock wise but just wanting to turn clock wise. This is set by turning the brush plate till you find the neutral position. Once you find that lock the four screws back down and drop the 3ed brush back down and set your output which is measured in amps. Moving the 3ed brush in the direction of rotation increases the amps and in the reverse direction decreases the amps. You should be looking for about 4 Amps out put to start with.

[big job]

Originally Posted by redmodelt

You need to set the whole brush plate to the neutral position. Lift the 3ed brush up and out of contact with the armature. Loosen the 4 screws that lock down the brush holder plate about a turn or just enough to be able to rotate the whole brush plate. Connect 6V's , negative to body and positive to the out put screw. What you are looking for is the generator not to motor anti clock wise nor clock wise but just wanting to turn clock wise. This is set by turning the brush plate till you find the neutral position. Once you find that lock the four screws back down and drop the 3ed brush back down and set your output which is measured in amps. Moving the 3ed brush in the direction of rotation increases the amps and in the reverse direction decreases the amps. You should be looking for about 4 Amps out put to start with.

Question 4 amps? Shouldnt it be set for the amount of amps you are using.
All I know is when a kid my old man use to say you kick up the third brush in
the winter and back it off in the summer. (this is back when most cars had
cutouts) All I know is I got a 5 amp discharge when my lights are on, which
are two headlights and one tail so Im figuring thats around 15amps and with
batt (coils my mag quit). Now setting the clocks back its dark in the am and
now 5pm and I drive the thing, cheaper to run than a F350 with a 460 for
sure.
sam

[redmodelt]

4 to 6 amps is a good place to start. If I am driving with my lights on I set the output to just be above 0 with the light on with the throttle leaver set to an engine speed of about 20 MPH. To me 15 amps sounds too high but there are other factors, how far do you drive, how fast does the motor start, what condition is you battery in?

[Doug Money]

The generator is rated at 100 watts max output. Amps x volts = watts. If you are putting out 7 volts (6 volt system), 7 volts x 15 amps = 105 watts. The harder you work the generator the shorter it will last. If most of your driving is in the daytime and you run on mag, how long does it take to recharge from starting? How many amps do you then need? If you run at night with the lights on, how much is it drawing from the system? I drive only occasionally at night so even if I have a discharge while driving, the next times of driving will put back what the lights took out that the generator didn't cover. My wording isn't always great so I hope that makes sense.

[big job]

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Either fact or fiction, back in the 6vt days, the old rule was, that it takes 5 miles to recover
the battery from starting. I dont know, all I know is mines starts like a V8 flathead.
and nothing beats those for starting.

[Doug Money]

Yes, so after the first 5 miles the battery should be recharged so you really don't need anymore after that. If you don't drive much at night but do occasionally, then a discharge with the lights on shouldn't matter much as long as there is a slight charge without the lights on. YMMV.

[Farmallcub49]

Running a voltage regulator is a wise thing to start with. I set our generators so they are about 1/2 to 1 amp with the lights on. I rarely run with the lights on and I don't want to cook my battery by overcharging it, but VR takes care of this anyway.

15 amps is way to high. If you run a cutout or diode cutout, the old rule was to set it to charge at about 8-10 amps, but always drive with your lights on to help prevent your battery from being overcharged.