12 Volt Conversion for Farmall H

I am installing a new alternator and it has two wires. Can someone tell me where to run each wire? I want to use my ammeter gauge as well I need to know how to hook up the wires. I bought the 12 volt conversion kit from yesterday's tractor and I have a yellow wire with a diode and a battery wire. Also would this be a self-exciting 1 wire or a non-self exciting alternator? I noticed one of my light wires is hooked up to my ammeter as well. Any help would be appreciated. Thank you, Johnny

If the kit contains a wire and a diode, one would ASSUME it is a standard "3-wire" alternator, rather than a less-desirable (goofy) "one-wire" unit.

Here's a simplified diagram.

<img src = "http://i167.photobucket.com/albums/u125/27Grainfield/424IH/Alternator%20Stuff/AlternatorHarness31.jpg">

Please note the diode, an "idiot light" or a 10 Ohm 10 Watt diode can be used interchangeably in the "excite" wire lead.


Another "Bob", Bob Melville has more complete diagrams his site linked below.
BobMs stuff

Thank you Bob for your help. On my new alternator it only came with one wire (yellow wire)and this plugs into the alternator; it also came with a diode too. Where does the single wire from the plug on the alternator go to? The diagram says I am to use my existing battery wire to hook up to the battery terminal on the alternator. The other end of my battery wire is currently hooked up the the positive side of my battery...is this correct? Isn't the battery wire suppose to run from the alternator to the ammeter? I hope this makes sense. Your picture you sent of your alternator looks nothing like the one I bought from YT. Thank you again for your help. Johnny

The single wire from the plug on the alternator goes to the + side of the ignition coil, or to the coil terminal of the ignition switch. This is the excite wire.

The other wire goes to the same post on your ammeter as the wire for the ignition switch. The other post of your ammeter goes to the starter or the + post on the battery.

The Alternator main (big) terminal should be connected to the load side of the amp meter. This is where the lights and ignition are attached) It is appropriate to use #10ga wire to do this. The H battery wire (refered to in the instructions) is the wire that was connected to the Bat termonal of the regulator. This wire does just what i described above, it goes to the load side of the amp meter. The diode wire attaches to the ignition switch (assuming it has a distributor and coil). If it has a mag, attach that lead to a normally open oil pressure switch to automatically excite the alt. This new switch (NAPA has them) is placed in the oil pressure port and "T"ed so it works with the oil pressure gauge. The switch has two terminals one will go to the battery + terminal connection at the starter switch, the other terminal is where the alternator small wire with diode is placed. If you do this Magneto setup, the diode is not needed. JimN

I am installing a new alternator on my Farmall H and I want to make sure I have the connections right. The battery wire that leads from the alternator terminates on the plus side of the ammeter? And the yellow wire that plugs into my alternator that wire terminates on the ignition switch? Also the wire that leads from the coil to the distributor is on the negative side of the coil. The positive side of the coil runs to the 6-volt resister, is this correct, does it matter which side of the coil goes to the 6-volt resister? The tractor has always started and runs good. Thank you for your help. Johnny

The wire going to the coil from the resistor should attach to the same polarity sign that it is. Thus if positive is hot, the wire connects to the positive terminal of the coil. The negative side attaches to the distributor/points/condenser, (which is negative on a negative ground)
The wire from the alt big terminal attaches to the load side of the amp meter.
I say this because the amp meter manufacturers do not mark them clearly, and they can be used for either polarity.
Assessment of Amp meter:
The supply side comes from the battery non grounded terminal (usually from a heavy #10 wire going to the starter switch big terminal which is connected to the hot battery cable). The load side of the gauge is connected to the light switch, the Voltage regulator (on a generator based system) or the big terminal of alternator (your case), and to the ignition button/switch/key.

If the lights work, and are attached to the load side of the amp meter, turn them on with the tractor off. If the meter swings left, to Discharge, it is correct. If it swings to the right, it is on backwards and just switch all the wires from one terminal to the other. This will make it read correctly.
If the lights do not work, watching the Amp Gauge carefully while turning on and off the ignition will also show the meter moving to the left (discharge) when on.
Good luck, and keep us informed with a new topic. JimN

Jim thank you for your reply. Since the positive side of my coil runs to my distributor should I change it to the negative cable on my coil and run the positive wire from the coil to the resistor? Also do I need to install a diode on the excite wire running from my alternator to my ignition switch or should I install a warning light here, I am a little confused about the back feed. One other thing I noticed there are not any fuses for protection....everything is hot. Would it be a good idea to install a 30 amp fuse on the wire going from the starter switch to the ammeter? Thank you for answering all these questions...I just want to get it right the first time without damaging my new alternator. I am also replacing all the wiring as well. Johnny

Do you have a wiring diagram to convert a 1954 Farmall H to 12 volts