12v from 3 brush Ford generator

[Pdgx]

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 ‘22 Mack with a special gear driven mount.

[Sparky]

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.

[hop up]

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

[jrelliott]

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.

[Pdgx]

Originally Posted by Sparky

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.

[Sparky]

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Originally Posted by hop up

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

Originally Posted by Pdgx

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 I’m 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.

[Badpuppy]

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.

[jwmckenzie]

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.

[Badpuppy]

Originally Posted by jwmckenzie

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

Correct.

Originally Posted by jwmckenzie

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.

[Sparky]

Originally Posted by Badpuppy

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.

[katy]

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.

[johnbuckley]

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.

[Sparky]

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.

[jwmckenzie]

Thanks...

[bobbader]

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

[jwmckenzie]

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?

[hop up]

Thank you Sparky Whats a fun projects regulator?

[jwmckenzie]

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

[Sparky]

Originally Posted by bobbader

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.

[Badpuppy]

Originally Posted by jwmckenzie

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.

[Badpuppy]

The "button" diodes (3 of them) are pressed into the deeper recesses of the aluminum rectifier heat sink in an alternator. A better choice for cutout mod is a stud mount type with heat sink compound for better heat transfer to the bus bar. Diode should be rated at least 25A. Use 12AWG for connection.

Example for negative ground -
https://www.ebay.com/itm/50-AMP-1000...-/121864495540

Positive ground type also available from the same seller.

[Sparky]

Originally Posted by Badpuppy

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.

Yes, but jwmckenzie is generally correct if your total power requirement is unchanged when switching to 12V.

For example, it you have a total of 60 watts of power requirement on a 6V system, the generator has to provide 6 volts x 10 amps = 60W. Converting to 12 volts, if the 6V light bulbs are replaced with equivalent power 12V bulbs (and the coil), the total power requirement will still be 60W, and now the generator will need to supply only 5 amps; 12V x 5 amps = 60W.

[Sparky]

Originally Posted by Badpuppy

The "button" diodes (3 of them) are pressed into the deeper recesses of the aluminum rectifier heat sink in an alternator. A better choice for cutout mod is a stud mount type with heat sink compound for better heat transfer to the bus bar. Diode should be rated at least 25A. Use 12AWG for connection.

Example for negative ground -
https://www.ebay.com/itm/50-AMP-1000...-/121864495540

Positive ground type also available from the same seller.

Those would work also assuming they fit in the case. There is no reason you can't mount one remotely if you don't care about mimicking an original cutout.

[jwmckenzie]

Thanks to both of you. I am looking at increasing the wattage needed, looking at 20 amp peak @12 Volts. I know an alternator would likely make a better choice, but I want the look of the Generator. This thing won't see much use, not likely to see 5 hours on the engine over a years time.

Plus, anyone can put an alternator on. Due to the load, I ordered a 40 amp diode earlier from the source suggested instead of the one recommended by Sparky

Thanks again... Big help.

[Pdgx]

Originally Posted by hop up

Thank you Sparky Whats a fun projects regulator?

They won’t tell you if or when they will make one for you.

[Kurt in NJ]

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They can't tell you if or when if the ic they use is not made anymore

[rotorwrench]

It would be hard for them to help a customer if they can't make the product. Expecting a different outcome from folks when they can't come through is problematic. If someone can't help you it doesn't mean that they are unhelpful. They just can't help you.

This is a far cry from being dishonest so don't poo-poo folks unless their is a good reason to do so.

[hop up]

Pdgx I never heard of the fun products and thought it would be more fun then a regulator:}
Thank you sparky for the information and plan to make one and put it into a original ford case like the fun products.

[jrelliott]

My only concern about the Fun Projects Voltage Regulator is that it regulates the output of the generator and not the generator field itself. You adjust the output of the 3rd brush to get 8 to 10 Amps then put on the regulator. Controlling the field strength which is essentially adjusting the 3rd brush is the best way to regulate the voltage out of the generator instead of converting to heat in the Fun projects regulator. The Fun Projects regulator does work very well. I am looking to find or design an electronic regulator that controls the field current. Tom Westberg has one for 6V, but not 12V. Finding electronic parts any more is difficult as there are no stores like the older Radio Shacks where you could find discrete components.

[Badpuppy]

@jrelliott - You're right about the FP regulator. It is a shunt regulator, which means it simply dumps excess generator power to ground. I figure it wastes about 1 HP at the high end. 1 horse doesn't sound like much until you consider there are only 40 to start with (or you try to wrestle a horse).

The series regulation used in Tom Wesenberg's design is much more efficient. It simply interrupts field current when set voltage is exceeded, limiting the output.

Regulators for a model A aren't that hard to design, considering the requirements are quite simple. A few common parts are all that is required.

There are many parts suppliers online. Just google for any part and you'll find lots of sources.

[jwmckenzie]

Originally Posted by Badpuppy

The "button" diodes (3 of them) are pressed into the deeper recesses of the aluminum rectifier heat sink in an alternator. A better choice for cutout mod is a stud mount type with heat sink compound for better heat transfer to the bus bar. Diode should be rated at least 25A. Use 12AWG for connection.

Example for negative ground -
https://www.ebay.com/itm/50-AMP-1000...-/121864495540

Positive ground type also available from the same seller.

So I have received a 40amp diode, it's a stud mount, How much heat should I expect from this diode if we are running say 20 amps @12 volts.

Jon.

[Badpuppy]

Originally Posted by jwmckenzie

So I have received a 40amp diode, it's a stud mount, How much heat should I expect from this diode if we are running say 20 amps @12 volts.

Jon.

Depends on forward voltage drop (Vf) of the particular diode. If you can't find the spec sheet, figure 1 volt drop: 1V x 20A = 20W. Grab onto a lit 20W bulb to find out how much heat sink is required. The copper bus inside an original cutout should suffice. Just be sure the arrow on the diode points toward the negative side.

[jwmckenzie]

Thank you....