The Ford Barn

Neshkoro · 09-15-2022, 04:18 PM

I'm not sure that I have a problem. I've done a lot of reading on this site and some testing and the more i read the more confused I get.
So, here's whats happening.
The starter is turning rather slow. Everything is stock as far as the generator and its system is concerned. The ammeter in the car shows about 5-6 amps while running at a good RPM. I tested voltage output of the generator while running. It's about 6.5 volts. With the car shut off the battery voltage is 6 volts.
Does that sound correct or not? I read on one of the other posts here that the voltage while running should be around 7.5 volts. i'm not getting anywhere near that. What should be the voltage and amperage output be?
Please advise.
Thanks,
Bill

rotorwrench · 09-15-2022, 06:45 PM

The norm is to set output amperage by adjustment of the movable third brush. Setting would be around 4 to 5 amps with headlights off. The battery is what regulates the voltage with a 3-brush generator. There is no voltage regulator. Voltage tends to follow amperage according to Ohms law so the higher the amperage output of the generator, the higher the voltage will be. A lead acid battery has 2.1-volts per cell so a fully charged 6-volt battery will be around 6.3 volts in a perfect world but an older battery will vary between 6.1 to 6.3 volts depending on condition. If it has set a while then it will lose some voltage over time. The battery connections have to be clean and tight to maintain good condition. A battery that is going bad will give problems like weak state of charge and slow cranking. The battery cables must be proper gauge to get minimal resistance during starting. A 2 gauge cable would be the normal size but a larger cable wouldn't hurt a thing. Starter switch condition has to be good as well.

The modern amp meters aren't as sensitive as the old originals. I don't trust them all that much to give an accurate reading. An ammeter can be tested by loading it with a known amount of amperage draw. It should read a discharge amperage that is pretty close to the load. The headlamps have the highest draw and should show a heavy discharge. With standard bulbs they can draw 7 or 8 amps depending on whether it has one or two tail lights. They can draw more depending on bulb wattages and types too.

The 3-brush generator just does the job but there isn't much margin for error. If the amp rate is set too high then the battery can get over charged with water loss to evaporation when charged on the high side. If charged on the low side then it may never get up to a full state of charge.

From your symptoms, you may be have a problem with the battery. It should be load tested to see if it will hold a decent charge. A lot depends on how old it is or whether it has set around too long and started getting sulfate build up on the plates. A person may need to charge it on a low amp charger for an 8-hour period and check the specific gravity of the cells unless it is a sealed battery. If that's the case, a load test would be the only way to test it.

Neshkoro · 09-16-2022, 08:24 AM

Thanks for the response. As far as the third brush is concerned, I tried to slide it with my finger but it seems stuck. In looking at some videos it appears that the brush should move rather easily. Maybe mine is stuck from dirt or other buildup. Im going to try to move it a bit to see if i can increase the amperage output.
How might I test the cutout?

ndnchf · 09-16-2022, 08:43 AM

As usual, Rotorwrench provided excellent guidance.

The 3rd brush can be stiff if it has not been moved in a long time. There are two fingers that lay against a ring that apply pressure and thus friction. This friction holds the 3rd brush in position, yet allows it to be moved as needed.

Here is a short video I made about adjusting the 3rd brush:

https://youtu.be/PL94VX3GIq8

I refurbish and sell original Ford cutouts. To test them I use a variable power supply and voltmeter. I adjust them so the points close in the 6.5 - 7.0 volt range. This is another video I made that explains in detail how I refurbish cutouts and shows how they are tested. I'd be glad to test and service yours if you want to send it to me.

https://youtu.be/rnuukBeJ6Zs

Steve

rfitzpatrick · 09-16-2022, 08:45 AM

[QUOTE=ndnchf;2166687]As usual, Rotorwrench provided excellent guidance.

YES he does, and I worked as an A&P for 40 years. His information is valuable

nkaminar · 09-16-2022, 08:57 AM

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Adding a volt meter to your ammeter is the best way to assure battery health. Charging should be 7.0 to 7.2 volts when the engine is at a fast idle or when running down the road. As stated the resting voltage should be 6.3 volts, after the battery has sat overnight. The volt meters can sit under the instrument panel on an aftermarket bracket. You will have do some searching. Try the usual vendors first.

It sounds to me that your battery is getting weak.

Neshkoro · 09-17-2022, 05:45 PM

The generator problem is fixed thanks to the help from you folks. The output is about 8 amps. The voltage is 7+volts. With a little force I was able to move the 3rd brush. I took the cutout off and apart. It seems to be working as it should. It must be a cheap replacement. It looks much different than some that I've seen on youtube, but it is working!
thanks again.
I'm always learning! And learning how simple these cars really are!

09-15-2022, 04:18 PM	#1
Neshkoro Senior Member Join Date: Dec 2020 Location: Central Wisconsin Posts: 105	Generator Output I'm not sure that I have a problem. I've done a lot of reading on this site and some testing and the more i read the more confused I get. So, here's whats happening. The starter is turning rather slow. Everything is stock as far as the generator and its system is concerned. The ammeter in the car shows about 5-6 amps while running at a good RPM. I tested voltage output of the generator while running. It's about 6.5 volts. With the car shut off the battery voltage is 6 volts. Does that sound correct or not? I read on one of the other posts here that the voltage while running should be around 7.5 volts. i'm not getting anywhere near that. What should be the voltage and amperage output be? Please advise. Thanks, Bill

09-15-2022, 06:45 PM	#2
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,431	Re: Generator Output The norm is to set output amperage by adjustment of the movable third brush. Setting would be around 4 to 5 amps with headlights off. The battery is what regulates the voltage with a 3-brush generator. There is no voltage regulator. Voltage tends to follow amperage according to Ohms law so the higher the amperage output of the generator, the higher the voltage will be. A lead acid battery has 2.1-volts per cell so a fully charged 6-volt battery will be around 6.3 volts in a perfect world but an older battery will vary between 6.1 to 6.3 volts depending on condition. If it has set a while then it will lose some voltage over time. The battery connections have to be clean and tight to maintain good condition. A battery that is going bad will give problems like weak state of charge and slow cranking. The battery cables must be proper gauge to get minimal resistance during starting. A 2 gauge cable would be the normal size but a larger cable wouldn't hurt a thing. Starter switch condition has to be good as well. The modern amp meters aren't as sensitive as the old originals. I don't trust them all that much to give an accurate reading. An ammeter can be tested by loading it with a known amount of amperage draw. It should read a discharge amperage that is pretty close to the load. The headlamps have the highest draw and should show a heavy discharge. With standard bulbs they can draw 7 or 8 amps depending on whether it has one or two tail lights. They can draw more depending on bulb wattages and types too. The 3-brush generator just does the job but there isn't much margin for error. If the amp rate is set too high then the battery can get over charged with water loss to evaporation when charged on the high side. If charged on the low side then it may never get up to a full state of charge. From your symptoms, you may be have a problem with the battery. It should be load tested to see if it will hold a decent charge. A lot depends on how old it is or whether it has set around too long and started getting sulfate build up on the plates. A person may need to charge it on a low amp charger for an 8-hour period and check the specific gravity of the cells unless it is a sealed battery. If that's the case, a load test would be the only way to test it. Last edited by rotorwrench; 09-15-2022 at 06:55 PM.

09-16-2022, 08:24 AM	#3
Neshkoro Senior Member Join Date: Dec 2020 Location: Central Wisconsin Posts: 105	Re: Generator Output Thanks for the response. As far as the third brush is concerned, I tried to slide it with my finger but it seems stuck. In looking at some videos it appears that the brush should move rather easily. Maybe mine is stuck from dirt or other buildup. Im going to try to move it a bit to see if i can increase the amperage output. How might I test the cutout?

09-16-2022, 08:43 AM	#4
ndnchf Senior Member Join Date: May 2012 Location: Fredericksburg, Virginia Posts: 759	Re: Generator Output As usual, Rotorwrench provided excellent guidance. The 3rd brush can be stiff if it has not been moved in a long time. There are two fingers that lay against a ring that apply pressure and thus friction. This friction holds the 3rd brush in position, yet allows it to be moved as needed. Here is a short video I made about adjusting the 3rd brush: https://youtu.be/PL94VX3GIq8 I refurbish and sell original Ford cutouts. To test them I use a variable power supply and voltmeter. I adjust them so the points close in the 6.5 - 7.0 volt range. This is another video I made that explains in detail how I refurbish cutouts and shows how they are tested. I'd be glad to test and service yours if you want to send it to me. https://youtu.be/rnuukBeJ6Zs Steve

09-16-2022, 08:45 AM	#5
rfitzpatrick Senior Member Join Date: May 2018 Location: Coral Springs, Florida Posts: 552	Re: Generator Output [QUOTE=ndnchf;2166687]As usual, Rotorwrench provided excellent guidance. YES he does, and I worked as an A&P for 40 years. His information is valuable

09-16-2022, 08:57 AM	#6
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 3,897	Re: Generator Output Sponsored Links (Register now to hide all advertisements) Adding a volt meter to your ammeter is the best way to assure battery health. Charging should be 7.0 to 7.2 volts when the engine is at a fast idle or when running down the road. As stated the resting voltage should be 6.3 volts, after the battery has sat overnight. The volt meters can sit under the instrument panel on an aftermarket bracket. You will have do some searching. Try the usual vendors first. It sounds to me that your battery is getting weak. __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past.

09-17-2022, 05:45 PM	#7
Neshkoro Senior Member Join Date: Dec 2020 Location: Central Wisconsin Posts: 105	Re: Generator Output The generator problem is fixed thanks to the help from you folks. The output is about 8 amps. The voltage is 7+volts. With a little force I was able to move the 3rd brush. I took the cutout off and apart. It seems to be working as it should. It must be a cheap replacement. It looks much different than some that I've seen on youtube, but it is working! thanks again. I'm always learning! And learning how simple these cars really are!