6 Volt generator to 12 volt?

[Retired Iron Peddler]

Does anyone know approximately what it would cost to rebuild a 6-volt DC generator to a 12-volt generator? My old 1950 B F Avery R/MM-BF was originally 6-volt positive ground and I have been running it on 12-volts positive ground for the past 20 years with the 6-volt generator disconnected. I'd been thinking about changing the generator to 12-volts and replacing the old 6-volt cutout with a 12-volt voltage regulator at the same time.

If I replace the generator with an self-regulating alternator, I would have to change the system from positive ground to negative ground and I don't know how that would affect the positive ground starter. Will the starter run in reverse? Changing the ignition coil/distributor to negative ground isn't a problem for me.

Rebuilding a generator will keep the tractor looking more like an original... except for the 12-volt battery in the battery box.


Bill

 

[MIKE R]

It is about $120 if I remember. I decided to keep mine 6volt but looked into the 12 volt rebuild.

 

[SPYDERLK]

Does anyone know approximately what it would cost to rebuild a 6-volt DC generator to a 12-volt generator? My old 1950 B F Avery R/MM-BF was originally 6-volt positive ground and I have been running it on 12-volts positive ground for the past 20 years with the 6-volt generator disconnected. I'd been thinking about changing the generator to 12-volts and replacing the old 6-volt cutout with a 12-volt voltage regulator at the same time.

If I replace the generator with an self-regulating alternator, I would have to change the system from positive ground to negative ground and I don't know how that would affect the positive ground starter. Will the starter run in reverse? Changing the ignition coil/distributor to negative ground isn't a problem for me.

Rebuilding a generator will keep the tractor looking more like an original... except for the 12-volt battery in the battery box.


Bill

I would think that just replacing the regulator with a 12V would do it. You would probably need a 1 or 2 Ohm power resister in the field exciter line.
larry

 

[droptop]

You could get a 12V alternator that has an isolated ground meaning that the alternator housing is not connected to the negative terminal. Most small automotive alternators are case ground, the negative terminal is connected to the alternator housing so that it must be used with a negative ground system. If you are looking for an alternator, try a marine style alternator because a lot of them are isolated ground units that could be used in positive or negative ground systems.

 

[Retired Iron Peddler]

I would think that just replacing the regulator with a 12V would do it. You would probably need a 1 or 2 Ohm power resister in the field exciter line.
larry

I don't follow what you are saying... just replace the 6-volt cutout with a 12-volt regulator? Isn't the armature and are field coils different in a 6-volt vs. a 12-volt generator?

Bill

 

[Mighty Dodge]

If your tractor has regulated 6 volt generator you can simply replace the 6 volt regulator with a 12 volt regulator. If it has a 3rd brush generator you'll need to adjust the 3rd brush so the generator puts out full voltage then wire in a 12 volt regulator. You'll also need to replace any 6 volt bulbs with 12 volt. If your tractor has a magneto no change to the ignition is necessary, however if it's coil you'll need to switch to a 12 volt coil or install a ballast resistor on the existing 6 volt coil.
This will keep the tractor looking original. If you're not concerned with appearance you can simply install a 12 volt alternator and make the above changes to the bulbs and ignition.

John

 

[Retired Iron Peddler]

If your tractor has regulated 6 volt generator you can simply replace the 6 volt regulator with a 12 volt regulator. If it has a 3rd brush generator you'll need to adjust the 3rd brush so the generator puts out full voltage then wire in a 12 volt regulator. You'll also need to replace any 6 volt bulbs with 12 volt. If your tractor has a magneto no change to the ignition is necessary, however if it's coil you'll need to switch to a 12 volt coil or install a ballast resistor on the existing 6 volt coil.
This will keep the tractor looking original. If you're not concerned with appearance you can simply install a 12 volt alternator and make the above changes to the bulbs and ignition.

John

It may be a third brush generator since I remember my late father adjusted the brushes to raise the voltage for charging an 8-volt battery. I remember him saying at that time something like it couldn't be adjusted much higher. It doesn't have a regulator, only a cutout.

I'll check for the third brush. There's an automotive electric (alternator, generator, starter) shop in town. When I have time, I may take in the generator and ask the older man who owns the shop if it can be changed, and if not, what it would take to change it.

I understand the ignition coil and lamp bulb changes. I'm running it on 12-volts now, and have been probably for 10 years, with a 12-volt coil with a built in resistor. The starter and starter relay are still the 6-volt versions; however, I don't stay on them very long. The tractor engine starts almost instantly with very few turns of the crankshaft.

Thanks,

Bill

 

[Soundguy]

I don't follow what you are saying... just replace the 6-volt cutout with a 12-volt regulator? Isn't the armature and are field coils different in a 6-volt vs. a 12-volt generator?

Bill

YES they are different fields.

around here.. 90$ gets a 6v converted to 12, if their are parts for it.

otherwise adapt a common genny over. or go to alt.

starter won't run backwards. series fields...

3 brush adapt to 2 brush easilly...

 

[Retired Iron Peddler]

3 brush adapt to 2 brush easilly...

Are you saying if my 6-volt generator is a 3-brush, it will easily convert to a 12-volt 2 brush? How? By replacing the field coils? I don't intend to do this myself, but want to know in advance if the generator shop knows what they are suggesting?

Thanks for the good info.

Bill

Bill

 

[SPYDERLK]

I don't follow what you are saying... just replace the 6-volt cutout with a 12-volt regulator? Isn't the armature and are field coils different in a 6-volt vs. a 12-volt generator?

Bill

The 12V gens Im familiar with were 2 brush. The field was fed by the regulator w enuf voltage/current to get ~ 14V off the armature. This reg fed voltage is way under 12V. Full 12V fed to the field would get you 30+V - and quite a bit of current from the armature. I did some welding with 3/32 rods using the field energized at 12V. Of course I would not recommend that ... you just need to get 14V at 10A or so to keep your 12V battery up. I think a 6V system designed like the one described would do this with a regulator change and maybe a lo value resistor in series with the field. Im not as confident with the positive to negative ground situation you also have. :confused3:
larry