3 wire alternator on 2 cylinder

So the alternator I had went out and so I desided to replace it with a 3 wire chevy alternator. I have it all wired (although the amp is backward lol) and it reads about 10 amps running. I looked through some wiring diagrams and see that some have a resister on the excitor wire and others dont. I heard that if it doesn't have it then it will charge at 100%, and I was getting a charge at like 16, little high lol, so I shut it off and started it again and it read like 14ish. My batter is bad, so could a shorted out battery be causing this? And shoudl I put a shunt into the system or just get a battery first? And if so what rating of a resister do I need? Thanks!

First, get a known good battery and charge it up before installing.

A Chevy alternator (Delco with internal regulator) should have a plug on the outer edge with 2 pins. Pin #1 is the excite or kick start voltage.

Pin #2 is battery sense pin, it senses battery voltage and controls charge level. It can connect to alternator output or anywhere on the charge line to the battery. There should be no resistor on this line.

The purpose of the resistor on Pin 1 (you could also use a lamp or a diode) is to prevent back feed to the switch and to the distributor ignition circuit. Without that isolation, sometimes when you turn off the switch the alternator will continue to feed back to the coil and the engine will not shut down. This will not be a problem with a magneto as it is a self powered system.

Resistor on #1 pin has nothing to do with charge output.

I think many people hook up a little light on one of those wires to act like a resistor ? A lot simpler to get a one wire alt. to use.
Also on alt. systems they use voltmeters because amp. meters will go nuts on them.

(quoted from post at 10:53:47 11/17/17) I think many people hook up a little light on one of those wires to act like a resistor ? A lot simpler to get a one wire alt. to use.
Also on alt. systems they use voltmeters because amp. meters will go nuts on them.

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Can't use a one wire on a 2 cylinder. They don't excite till around 1500 rpm and the jd doesn't get to it. I have to rev the crap out of my farmall to get it to start charging.

Make all known repairs before diagnosing problems . If the battery is bad replace it .A bad battery can cause a lot of problems . You know they make a one wire alt. like
the one you have .

(quoted from post at 10:51:33 11/17/17) First, get a known good battery and charge it up before installing.

The purpose of the resistor on Pin 1 (you could also use a lamp or a diode) is to prevent back feed to the switch and to the distributor ignition circuit. Without that isolation, sometimes when you turn off the switch the alternator will continue to feed back to the coil and the engine will not shut down. This will not be a problem with a magneto as it is a self powered system.

Resistor on #1 pin has nothing to do with charge output.

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Ah so the resister only makes it so the coil doesn't get power when the switch is shut off? That makes sense because I had to run a separate switch for the ignition because it kept running after turning off switch. What type of resister or diode do i need. Like a rating. Or is there one they make specifically for this?

Actually, I bought an led indicator. Would I be able to use that?

IIRC ? you put a smaller pulley on them and spin them faster.
One guy told me he used a marker lamp with the 194 bulb in it. That was the same bulb used in most car dash lamps for the alt. lamp.

1. On the #1 feedback pin, a diode is a one way device that will pass current in one direction and block current in reverse direction. A lamp or resistor will pass current in either direction but will limit the current to a much lower level than is required by the ignition system. So, with feedback either blocked, or limited below the operating demand of the ignition system , it will allow the engine to shut down.

2. A diode rated 3 amps @ 50 volts or greater on either rating will work. The amp rating is the amount of forward current the diode is designed to pass, and the voltage rating is the reverse voltage that the device is designed to withstand without failure. Radio Shack or an electronic repair shop should have something that would work.

3. An LED will not work. A common diode, indicator lamp, or resistor have all been used. If you use a lamp, get an indicator lamp with 2 leads and a non grounded case. An auto parts place should have several options. One lead to coil side of ignition switch and other side to #1 pin on alternator plug. A 10 ohm 10 watt resistor should also work.

4. I have 3 tractors converted to alternator and all 3 still have original ammeter with no problems. I have seen problems with a cheapo replacement ammeter having some needle bounce.

Guess again. I have 3 one wires on two cylinders here. THey all work just fine, and start charging about 750 engine RPM. And yes, I use the standard pulleys.

I got a GM one wire on mine and it charges at any rpm. I don't have to rev it up at all. I bought from a starter and generator shop and the guy says its got the diodes in it where it don't have to rev it up. You may want to call your local starter generator shop and see if they can fix you up.

(quoted from post at 20:45:39 11/17/17) I got a GM one wire on mine and it charges at any rpm. I don't have to rev it up at all. I bought from a starter and generator shop and the guy says its got the diodes in it where it don't have to rev it up. You may want to call your local starter generator shop and see if they can fix you up.

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Must just be a different rated diode then?