Farmall H Altenator wiring

Dave Miller · Dec 12, 2009

I am changing from a 6 volt system to a 12 volt system on a Farmall H. The regulator is mounted on the gen. and it has a magneto. The system I bought shows the wiring diagraham for a coil and distributor. I have talked to a few people and have not gotten a straight answer on the correct way to do the wiring. If anyone has some advise and/or the correct way to do the connection, please advise. Thanks for any and all the help.

David G · Dec 12, 2009

Most of the wiring connections can be ignored because you have a mag. The main thing to remember is that you will have to reverse the battery cable / ampmeter polarity and change the light bulbs from 6V to 12V. You will only need to connect the heavy wire from the ampmeter to the alternator, if it is a one wire model. The other wires can be abandoned.

AllanC · Dec 12, 2009

It all depends what type alternator you are using, as you need to follow the diagram for that alternator. Simplest is a "one wire" but if using one with a powered regulator ( like a big Delco) you have to provide power to the regulator. Best is switched power, but you can just add a jumper. The draw is very small. The Magneto, as you likely know, has no need of external wiring.

Janicholson · Dec 12, 2009

If you go with a three wire setup (Hitachi or Delco) the S wire on the Hitachi goes to the alt output terminal (real short wire) the L wire goes to 12 volts. You can do one of two things, either put an oil pressure (on with pressure NAPA switch, then to the starter switch terminal from the positive bat terminal (neg ground))so it starts charging when the Oil Pressure is on, or put a manual exciter button on the wire to the start switch as above. Momentary contact push button NAPA or other. This will start it charging when running and you push it once. Do not (as noted below) change the wiring on the Mag, or attach any thing to the ignition kill switch. JimN

Janicholson · Dec 12, 2009

I forgot to ad the #1 small terminal on a Delco 10SI is the 12v terminal (same as the l on Hitachi)
The #2 terminal goes to the alt output stud. JimN

Farmall H Altenator wiring

Dave Miller

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David G

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AllanC

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Janicholson

Well-known Member

Janicholson

Well-known Member

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