Generator adjustment?

Earle

Earle

Senior Member
Gentlemen,

Forgive the repetition as I know this has been discussed before, but I didn't need to know back then and didn't take notes:

How do you adjust the amp output of the generator?

I have a '31 roadster with a correct, stock generator (not "powerhouse"). I recently installed one of those voltage regulators that looks like a standard cut-out switch. It does a good job of "regulating" (I think) under different accessory demands, but the ammeter still goes 2-3 amps negative with the headlights on. With all lights off, the ammeter shows a charge of only 1/2 amp. Shouldn't it be more like two to four? After long drives, using headlights periodically, the battery needs a trickle charge to bring it back up to full-charge again.

I removed the cover-ring from the aft end of the generator but among the various miscellaneous "gizmos" I see inside, it isn't obvious to me which item is the one I need to "loosen the lock nut on to rotate the brush" one way or the other - if I have the jargon right!

And, which direction - same or opposite the direction of rotation - do I rotate the brush to increase amp output?

Thank you in advance for your expert assistance!

Earle
Wilmington, Delaware
 
Setting the generator third brush​
A) Loosen the generator dust cover bolt and lift off the dust cover.
B) Loosen the third brush nut and shift the third brush assembly counterclockwise (as viewed from the front of the car) as far as possible.
C) Start the car and bring the engine to a high speed that produces the maximum charge from the
generator. Turn on lights and observe an Ammeter reading of 7 to 9 Amps discharge.
D) Advance the third brush setting clockwise (as viewed from the front of the car) until the Ammeter
shows a slight charge of 1/2 to 1 Amp with engine at this same high speed. The generator is now
putting out 8 to 11 Amps. This should be the correct setting for the third brush.​
Do not advance the third brush further or the setting will be too high! - The correct setting will occur with the third brush advanced only slightly further than the center of its mechanical adjustment range. The third brush must not be advanced further.​

E) With engine still at high speed turn off lights and observe that the charge rate jumps to 8 to 12 Amps where the charge rate will remain until the battery reaches full charge. It may take a few seconds, a few minutes, or a few hours for the battery to reach full charge. When the battery is nearing full charge, the charging rate will taper off until only 1 to 4 Amps of charge current remain.​
Make certain that the battery charge rate does not exceed 15 Amps during this charge time​
. ​
A lower setting of 10 to 12 Amps is best and will result in longer generator life. If charge rate is ever allowed to exceed 15 Amps, generator damage will result. Do not attempt to readjust the third brush once the regulator has begun to taper the charge since the regulator will tend to compensate for the adjustment and it is very easy to advance the third brush too far which will result in generator or voltage regulator failure.
F) Tighten the third brush nut.
G) Check proper operation by idling the engine with lights off and then quickly increasing engine
speed. The Ammeter should show a momentary high charge rate (8 to 12 Amps) then regulator action should be observed by a noticeable decrease in charge rate.
H) Install the generator dust cover and tighten the dust cover bolt.​

IMPORTANT!​
​
- A final check must be made after 24 hours of no operation of car or battery by starting the car with the starter and bringing the engine immediately to high speed. With all lights off the Ammeter reading should be at or below 15 Amps. If higher than 15 Amps, reduce the third brush setting immediately! This is the maximum reading you should ever see and it will soon taper off once the battery comes up to charge. Thereafter the peak reading will be in the 8 to 12 Amp range. This first reading is higher right after the car is first started because the battery voltage is lowest since the battery has not been charged for 24 hours.​

 
Thanks, Mike.

I'll give it a try.

A question for Blessyouboys: You said that if I have a voltage reg. I don't have to adjust the third brush. Does that mean that the generator output (brush position) could be set anywhere and the regulator will make everything happy? That doesn't intuitively sound right.

I think for now I'm going to go with Mike's instructions.

Thanks, Gents for the input.

Earle
 
A's did not have a regulator, the device on the gen is a "cut out" relay and it is there to prevent battery drain when the gen is not spinning. Thats why there is an adjustable brush. If the headlights are used a lot, it should be adjusted higher than normal. If too high and the headlights are not used, you can burn out bulbs and boil the battery.If too low the battery wont get fully charged.
 
Thanks, Rich. I am aware that A's had a cut-out switch instead of a voltage regulator. In my original message above, I noted that I had replaced the cut-out with a regulator. That's what led to my line of questioning re. brush adjustments.

Earle
 
Call the company you purchased the regulator from. My intuition says you need to set the third brush to charge the maximum and let the regulator control the amount of charging that occurs.

Charlie Stephens
 
Charlie Stephens said:
Call the company you purchased the regulator from. My intuition says you need to set the third brush to charge the maximum and let the regulator control the amount of charging that occurs.
Click to expand...

I just installed that same regulator and I'm pretty sure the instructions said to set the third brush with the cutout installed prior to installing regulator to ensure it does not exceed the amount the regulator is designed for. Im running a B genny so its set to 18amps but I think the A was supposed to 13 or 14 at high rpm. The instructions made it sound pretty sensitive to high current so be care you dont push it up too far if you leave it on while adjusting. Perhaps the manufacturer can give an alt method as suggested above. The instructions are on the fun projects website if you lost them.

Bob NJ
 
Thanks, RTC1930 & everyone.

I'll go back and dig into my "files" for the Fun Projects instruction sheet. I recall it talking about being careful not to set the output too high or the regulator could be smoked.

But my original question still stands as to exactly what I am to look for to make the adjustment, if necessary, once I have the protective cover ring removed from the generator - and which way it needs to be rotated to increase vs. decrease the output.

Matbe someone can provide a link that has detailed adjustment instructions with pictures of the inside of the gen. ?

Thanks,

Earle
 
If all you need to know is which way to rotate the third brush holder,the easiest way to remember is,up is down,and down is up.If you are standing there looking at the opening in the generator,looking at the third brush,if you want more amps push it down.If you need less amps,roll it up.Up downs the amount of amps,and down ups the amount of amps.
 
3c14db98.jpg
 
Earl, Please be careful if you go to move the third brush while engine is running, DON'T use a metal screwdriver or the like, use a wood stick or old plastic toothbrush-- Think "insulated". I'm sure you know that anyway-Best, Pete.
 
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