6 or 12 volt question again

Charlie M · Jun 3, 2013

A few days ago I asked how you can tell if a tractor is 6 or 12 volt when the battery is missing. The tractor is a Cub that is used for mowing and hasn't been ran this year.I took a look at it today concerning how its wired up. The tractor is a 1947 with a mag that has been converted to an external coil and a motocraft alternator has been added with what looks like to me an external regulator. I didn't see a resistor to the coil but the coil is tucked up under the hood and could be 12 volt.I know most alternators are 12 volt but isn't it possible to be a 6 volt? I could disconnect the alternator to try starting the tractor but I don't want to ruin the coil if I put on the wrong battery and eventually I need to get the charging system working. There is a lot of wiring on this thing and its wrapped and several ends not connected to anything so its hard to trace. I've got lots of experience with Farmalls but not with Cubs. Any thoughts on how to proceed? In my opinion someone has made this tractor a lot more complicated than it needs to be.

CNKS · Jun 3, 2013

If it has an alternator it is 12 volt. I think it is possible to have a 6V alternator, but they are pretty rare. Consider it 12 volts.

D beatty · Jun 3, 2013

They do make a 6 volt alternator have one on a Farmall B.Like the 6 volt alternator It keeps the battery charged better if the tractor is used for short period of time.

CNKS · Jun 3, 2013

You may have the only one on the forum -- maybe someone else will have one, also.

S2710 · Jun 3, 2013

Yes you can get a 6 volt alt. I had one on a Farmall H. It was off of a Fairmont Motor Car that was used on the railroad.

Bob

sflem849 · Jun 3, 2013

Why don't you just take a 6 volt battery over there and see if it works?

Tom Fleming · Jun 3, 2013

good advice. test it with a 6 volt battery. the lights will either be bright (6 volt system) or dim (12 volt system). If you go the other way, the 12 volt will blow out the 6v lights.

sflem849 · Jun 3, 2013

(quoted from post at 18:39:56 06/03/13) good advice. test it with a 6 volt battery. the lights will either be bright (6 volt system) or dim (12 volt system). If you go the other way, the 12 volt will blow out the 6v lights.

Wouldn't it fry the coil, too?

John T · Jun 3, 2013

If you make it to the "Half Century of Progress" show betcha they will have some there also. Its the Mother Load..........

John T

Tom Fleming · Jun 3, 2013

No, not if you don't run it for an extended period.

D beatty · Jun 4, 2013

You can get 6 volt Alternators from Napa but I got mine from a guy in Michigan that rebuilds and takes new 12 volt alt.and builds 6,and 8 volt alternators. He also has differant size pullies to get the rpm you need so it will start charging with the lower rpm engines. I put an alternator on my B because the generator was shot and to replace it was way over $200.00 and alternator was cheaper and with all the short run periods of time it keeps battery charged, The any thing I had to change was the bottom mounting bracket and it fits right in the same place as generator and looks like it cane from factory with it.

mkirsch · Jun 4, 2013

If you have to run out and buy a 6V battery, it's not worth it.

Odds are you have a 12V laying around, or one you can borrow from something else.

12V is fine. Worst case scenario you run the engine for 20 minutes and burn out the coil. A new coil costs less than a battery that you may or may not need. Instead of burning out the coil just run the engine a few minutes and feel the coil periodically to see if it's getting hot.

You're not going to hurt anything else running 12V unless the alternator is totally weird and ends up being positive ground...

It may just behoove you to take the hood off and SEE what you're working with. You can get part numbers off the alternator, regulator, and coil once the hood is off.

sflem849 · Jun 4, 2013

(quoted from post at 12:19:57 06/04/13) If you have to run out and buy a 6V battery, it's not worth it.

Odds are you have a 12V laying around, or one you can borrow from something else.

12V is fine. Worst case scenario you run the engine for 20 minutes and burn out the coil. A new coil costs less than a battery that you may or may not need. Instead of burning out the coil just run the engine a few minutes and feel the coil periodically to see if it's getting hot.

You're not going to hurt anything else running 12V unless the alternator is totally weird and ends up being positive ground...

It may just behoove you to take the hood off and SEE what you're working with. You can get part numbers off the alternator, regulator, and coil once the hood is off.

The way he talked I ASSumed he had tractors at home that were 6 volt. I agree, not feasible if you have to buy one.

Couldn't you also pull it without a battery and see how much the charging system puts out or would the charging system not work because the system was not complete?

Owen Aaland · Jun 4, 2013

All it takes on a Delco 10SI alternator to convert it to 6 volt is to replace the regulator.

They can also be converted to positive ground but it is a little more complicated. To convert from negative to positive ground you need a different rectifier bridge, another insulated screw, and a jumper wire. The regulator is left insulated from the case so you continue to use the same regulator provided it is a self energizing regulator.

A standard regulator could be used but would require some additional external wiring and relay type switch.

teddy52food · Jun 4, 2013

Alt won't charge without a battery hooked up.

Owen Aaland · Jun 4, 2013

(quoted from post at 22:23:19 06/04/13) Alt won't charge without a battery hooked up.

A self energizing regulator will allow an alternator to start to charge even if there is no battery connected to it.

6 or 12 volt question again

Charlie M

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CNKS

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D beatty

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CNKS

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S2710

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sflem849

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Tom Fleming

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sflem849

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John T

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Tom Fleming

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D beatty

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mkirsch

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sflem849

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Owen Aaland

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teddy52food

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