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Old 12-30-2020, 08:09 AM   #1
Pdgx
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Default 12v from 3 brush Ford generator

Is anyone using a Ford 3 brush generator on a 12v system ?

With the Fun Projects conversion regulators unavailable, how did you do it ?
What regulator are you using ?

There is no starter involved, and a standalone magneto, so the usage will be minor. Only need it for 12v conversion lights in former carbide lights.

Changing to a different generator is not really feasible as it is used on a Ď22 Mack with a special gear driven mount.
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Old 12-30-2020, 09:11 AM   #2
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Default Re: 12v from 3 brush Ford generator

Yes, I do myself and I'm sure many others on this board do also. My generator is unmodified except I repolarized it for negative ground. I do have a Fun Projects regulator, but before I got that I was running a home-made diode cutout.
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Old 12-30-2020, 09:14 AM   #3
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Default Re: 12v from 3 brush Ford generator

Sparky can you please share how to do that. I have a few 3 brushes that need to be converted and thought only 2 brushes could be done.. thank you
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Old 12-30-2020, 09:22 AM   #4
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Default Re: 12v from 3 brush Ford generator

After repolarizing the generator, the battery becomes the limiting factor on how much voltage the generator produces. You must have a battery! If you do not have this load will burn out the bulbs as generator voltage can go as high as 40 Volts. Same condition as with a bad ground connection. You can use a voltage regulator to reduce the amount of current going to the battery same as moving the 3rd brush.
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Old 12-30-2020, 09:29 AM   #5
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Default Re: 12v from 3 brush Ford generator

Quote:
Originally Posted by Sparky View Post
Yes, I do myself and I'm sure many others on this board do also. My generator is unmodified except I repolarized it for negative ground. I do have a Fun Projects regulator, but before I got that I was running a home-made diode cutout.
I’m looking for a way to change this generator due to its drive link to the Mack engine. This generator was just rebuilt, so it is in great condition.

Any detail info that can be provided, would be greatly appreciated.

Last edited by Pdgx; 02-23-2021 at 08:15 PM.
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Old 12-30-2020, 09:42 AM   #6
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Default Re: 12v from 3 brush Ford generator

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Quote:
Originally Posted by hop up View Post
Sparky can you please share how to do that. I have a few 3 brushes that need to be converted and thought only 2 brushes could be done.. thank you
Quote:
Originally Posted by Pdgx View Post
I contacted the (not-so) Fun Projects people, who were most unhelpful. They would not provide any availability if an order was placed, and other forum posts indicate they had been bought out or shut down producing the conversions.

So Iím looking for a way to do a similar change to This generator due to its drive link to the Mack engine. This generator was just rebuilt, so it is in great condition.

Any detail info that can be provided, would be greatly appreciated.
I'm happy to help, but I'm not sure what the question is. Are you asking how to make a diode cutout? If so I can take some photos of the one I made. As I said my generator is completely stock.
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Old 12-30-2020, 10:04 AM   #7
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Default Re: 12v from 3 brush Ford generator

The generator itself needs no modification. Connect the battery through a switch and cutout*. Polarize the generator if necessary by touching hot battery to the output post for half a second. Start engine and adjust 3rd brush for proper output, 14.5-15V. You're good to go.

*Cutout must be set for 12.6V. Diode type must be correct polarity.

Note voltage varies with rpm and load.
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Old 12-30-2020, 10:05 AM   #8
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Default Re: 12v from 3 brush Ford generator

Sparky, so the generator needs no modifications to run the 12V system, simply re-polarize it for negative ground?

Will the standard cutout work with 12V, either the original or the diode ones available from the parts houses? If not also interested in the diode cutout you made.

Thanks.

Jon.
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Old 12-30-2020, 10:19 AM   #9
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Default Re: 12v from 3 brush Ford generator

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Sparky, so the generator needs no modifications to run the 12V system, simply re-polarize it for negative ground?
Jon.
Correct.

Quote:
Originally Posted by jwmckenzie View Post
Will the standard cutout work with 12V?
Not very well. The operate point is different, should not cut in before output reaches battery voltage. You can find 12V cutouts online.

Diode cutouts are one-way valves and work with either voltage but must be oriented correctly, positive or negative.
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Old 12-30-2020, 10:26 AM   #10
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Default Re: 12v from 3 brush Ford generator

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Correct.



Not very well. The operate point is different, should not cut in before output reaches battery voltage. You can find 12V cutouts online.

Diode cutouts are one-way valves and work with either voltage but must be oriented correctly, positive or negative.
That's right. The original-style cutouts are essentially a wire-wound relay, and are designed to operate at a specific voltage and/or current, so are not likely to work correctly on 12V. A diode cutout doesn't care about voltage, just polarity. The polarity can be either positive or negative ground, depending on which diode you choose. I will post pictures later.
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Old 12-30-2020, 11:23 AM   #11
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Default Re: 12v from 3 brush Ford generator

If'n you go w/a diode make sure the amperage rating is high enough for the intended use.

A good rule of thumb is to use a diode that is rated for 2X the expected maximum current.

Diodes are cheap so going larger doesn't cost a lot more.
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Old 12-30-2020, 01:11 PM   #12
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Default Re: 12v from 3 brush Ford generator

Er, are you on the best forum for this question? magneto? carbide lights? as has been said ...yes the 6v ford 3 brush can put out enough for 12 v systems, most people don't have a regulator fitted but use the original style of cutout ( they are specifici to either 6v or 12 v ) or a diode or a fun projects gizmo.
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Old 12-30-2020, 07:03 PM   #13
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Default Re: 12v from 3 brush Ford generator

OK, here are the pictures I promised. The diodes I used are for a Delco 10DN alternator. They are rated for 25 amps. Just google "10DN diode" and you can find them from various sources. I got mine from eBay. The ones with the red leads are positive diodes, used for positive ground systems. The ones with the braided leads are for negative ground, which is what I have.

I took the cover off my cutout so you can see the internals. All the relay guts were removed. You can just make out where the relay contacts used to be attached to the upright metal bar. This bar is electrically connected to the generator output stud. Drill a hole in this bar the correct size for a press fit of the diode. A tight fit is important as the metal bar has to act as a heat sink.

The diode wire gets soldered to the metal part of the cutout that is connected to the output lug, where the battery wire gets attached.

I used this for a couple of years until I got a Fun Projects regulator, so now I keep it as a spare.
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Old 12-31-2020, 07:10 AM   #14
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Default Re: 12v from 3 brush Ford generator

Thanks...
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Old 12-31-2020, 08:55 AM   #15
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Default Re: 12v from 3 brush Ford generator

So Sparky, Nicely done. Can you post the spec/part number/source on the diodes you are using. This would be most helpful for those of us who are capable of soldering and mounting the unit but "electronically challenged" when it comes to choosing the appropriate diode.

Thanks
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Old 12-31-2020, 09:18 AM   #16
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Default Re: 12v from 3 brush Ford generator

How many amps will an original generator put out at 12V? I have read that the 6V generator will output ~22 amps. If 22 is right then should we only expect ~10 amps out at 12V.

Do I have the math right?
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Old 12-31-2020, 09:31 AM   #17
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Default Re: 12v from 3 brush Ford generator

Thank you Sparky Whats a fun projects regulator?
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Old 12-31-2020, 09:34 AM   #18
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Default Re: 12v from 3 brush Ford generator

Here is a link.

http://www.funprojects.com/products/10505r.aspx#:~:text=%20%20%20%20Part%20No.%20%20,% 20%20$82.35%20%204%20more%20rows
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Old 12-31-2020, 10:19 AM   #19
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Default Re: 12v from 3 brush Ford generator

Quote:
Originally Posted by bobbader View Post
So Sparky, Nicely done. Can you post the spec/part number/source on the diodes you are using. This would be most helpful for those of us who are capable of soldering and mounting the unit but "electronically challenged" when it comes to choosing the appropriate diode.

Thanks
Actual part numbers can vary depending on the source. The simplest way to find them is to just google "10DN diode". Here are a couple of links I found:

https://store.alternatorparts.com/10dn-diodes.aspx

https://www.ebay.com/itm/Delco-10DN-...15bf%7Ciid%3A1

The ones on eBay are a bargain and are the ones that I used. I first got a set of positive ones and then realized (after assembling in the shell) that it was backwards for my negative ground system, so I had to order a set of negative diodes.

Last edited by Sparky; 12-31-2020 at 10:48 AM. Reason: fix typo
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Old 12-31-2020, 10:20 AM   #20
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Default Re: 12v from 3 brush Ford generator

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How many amps will an original generator put out at 12V? I have read that the 6V generator will output ~22 amps. If 22 is right then should we only expect ~10 amps out at 12V.

Do I have the math right?
Math's ok but not the reasoning. If the gen actually is capable of 22A at 6V without melting then it is capable of 22A at 12V as well. This means if you get 132 watts output at 6V then you get 264 watts out at 12V. That's one reason for converting to 12V.
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