3rd brush question

[woodrow]

I think I need to increase the output of the generator on our '37 pickup. Which way do I move the 3rd brush, up or down, to do that? After moving the brush what would be the optimum voltage input to the battery? I should hasten to say that I have a hard time understanding electrical stuff, but MOST of the time, can follow directions. There are times I get caught out at night with the truck and when I turn on the headlights it seems to leave the battery a bit weak. The battery really takes a beating if I turn on the fog lights and headlights. Is it okay to move the brush while the truck is running or better to do it with the engine off? We're still 6 volt, positive ground. Thanks,

[Jack E/NJ]

http://www.fordbarn.com/forum/showthread.php?t=140226

Jack E/NJ

[MGG]

To increase the output, from the driver seat perspective, move the brush clockwise, or, to the right. I did it with the engine running at about 1500 rpm on my 1934 BB. I made a wooden stick with two small prongs so it would not slip off and short something out inside the generator during the process. My wife was watching the ammeter inside the cab so I could stop when my desired output was reached. I installed the regulator which looks like a cutout and followed the instructions exactly and I am very happy with the result. After starting, the generator puts out around 7 amps and then after about 5 minutes it has the starting charge replaced and settles in at about 1-2 amps. I have a very happy 6 volt regular battery and the generator only gets warm to the touch.

[Karl Wolf]

I would consider charging the battery to top, and use a volt meter to set the voltage at about 7v, or just a touch less. With the lights on.

I set the third brush on my 6v Harley by guessing. It was frying headlights.

I remember my father telling me about people driving long distances leaving the lights on so as to not over charge the battery.

Karl

[koates]

Woodrow, The early ford 1932 to 1938 third brush generator is capable of around 15 amps safe maximum output. Any more will overheat the armature windings and burn it out. Having said that the third brush setting is only a maximum setting and in no way regulates the charge rate up or down to compensate for battery condition or various loads such as lights turned on or off. That generator will never be able to cover all the current draw of your headlights plus foglights and other items turned on all at the same time. If you set the brush at a max of 15 amps then during daytime running with no lights on then the battery will be overcharged and overheated if running for any longer than a half hour or so. The third brush is always set using an ammeter and NOT by using a voltmeter as has been suggested by others. An electronic voltage regulator which looks like the original round cutout on top of the generator is available from FUN PROJECTS, in 6 volt, pos ground for your car. Also available in neg ground and 6 or 12 volts. This unit is quite good and will partly solve some of the third brush drawbacks but will not increase the overall maximum output of 15 amps. I have the third brush on my 1934 Ford set to charge only around 5 amps on the cars ammeter which will not overcharge the battery during daytime running . If I drive at night it will not cover the headlights but is OK for half an hours or so driving with lights on. Regards, Kevin.

[woodrow]

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Thanks for the good help on the 3rd brush question. This afternoon I moved the 3rd brush to the right, clockwise. Now when the truck is at idle the ammeter shows neutral. With the truck at high idle or on the road the ammeter shows about a 4 to 6 amp charge. I hope I understood the directions correctly. Anyway, thanks for your help.

[Floyd]

I am not sure of the instructions posted above. According to the Ford service bulletins, to increase the charging rate, move the third brush in the direction of rotation of the generator. This simply means that since the engine/generator rotates clockwise when viewed from the front of the car, then you move the brush upward or clockwise as viewed from the front of the car. Not from the driver seat position. I don't think this would change for a BB with a 4 cylinder but who knows.
Just an opinion, check the service bulletins, they are correct.

[MGG]

That is correct. Clockwise from the front of the car increases the charge rate. Not as viewed from the seat as I stated before.

[rheltzel]

Two years ago, I installed one of Fun Project's voltage regulators that looks like a cut-out. You set the 3rd brush at max and it takes care of the rest. It has worked flawlessly. I highly recommend them. Here's a link to their website:

http://funprojects.com/products/5055r.aspx

[flatheadmurre]

A lowtech version of adjustable charging is used on the tractors running 3brush sytems.
They have a resistor in the grounding side of the 3rd brush circuit.
A switch across th resistor is closed when using headlights giving a higher charge and when open the resistor gives a lower charge for daytime running.

[Tom Walker]

Originally Posted by rheltzel

Two years ago, I installed one of Fun Project's voltage regulators that looks like a cut-out. You set the 3rd brush at max and it takes care of the rest. It has worked flawlessly. I highly recommend them. Here's a link to their website:

http://funprojects.com/products/5055r.aspx

With respect, with regard to the Fun Projects voltage regulator, the instructions state very clearly that you dont set the 3rd brush to max.

You start with fully charged battery, and the 3rd brush moved to lowest output position, run engine at max generator output revs, turn on all lights and other electrical draw, then move brush to higher output position until ammeter reads half to one amp.

If the ammeter ever reads over 20 amps, instructions say to reduce output of generator.

Having run mine now for six months, I reckon it will pay for itself in no time by increasing the life of my battery, and probably the generator.

[rheltzel]

Originally Posted by Tom Walker

With respect, with regard to the Fun Projects voltage regulator, the instructions state very clearly that you dont set the 3rd brush to max.

You start with fully charged battery, and the 3rd brush moved to lowest output position, run engine at max generator output revs, turn on all lights and other electrical draw, then move brush to higher output position until ammeter reads half to one amp.

If the ammeter ever reads over 20 amps, instructions say to reduce output of generator.

Having run mine now for six months, I reckon it will pay for itself in no time by increasing the life of my battery, and probably the generator.

I stand corrected. I set mine at full output--about 22 amps--and so far, no issues. But I guess it's always better to follow the instructions. If I end up having any problems, I'll report.

[koates]

rheltzel, 22 amps is too high for an early 3 brush ford generator. They are rated to a max of 15 to 18 amps depending on generator model. If you had a long run at night with all lights on, gen charging at 22 amps it will get too hot and maybe the armature windings could burn out especially if it is an original armature winding, (read old and brittle). You should knock that third brush back to a max of 16 amps. Better to error on the safe side. Regards, Kevin.

[rheltzel]

Thanks, Kevin. I guess I'd better "throttle back" a bit.