Alternator-rewiring

[18vtx00]

hey guys, so I just picked up this 350B. The starter stayed engaged a few times so I pulled the panel down to find a mouse nest and some chewed and corroded wires. I am rewiring the whole machine as it's been partially hacked w/ several repairs. My question is that someone installed a 3 wire GM alternator but and then wired in a toggle switch for the B+ circuit. Are these known to overcharge? I'm assuming someone was just cutting corners, haha

[Tom in Mo.]

My 450 is the same way but with a blade switch on the negative battery post. The battery will drain if there is not a resistor installed between the ignition switch terminal and the #1 terminal on the back of the generator. A 10 OHM / 2 watt+ resistor and a 5 amp / 50 volt diode installed inline on the wire from the ignition switch to the number 1 terminal of the gen should stop the drain unless you have other problems. On the diode the cathode + side goes to the alternator and the anode side toward the ignition switch. Note the resistor should not be taped into a wire bundle as it will get hot.

[MarkW]

When you say it is a 3 wire alternator, you mean it has an internal regulator and the plug on the side looks like this:


I converted mine a year ago and it works just fine, here is how you should modify yours-

First, go to NAPA or Autozone or wherever and get an "Alternator Harness Pigtail Connector" (that phrase is redundant, but some places call it a pigtail and some call it a connector and some use the term harness so if you call it that the parts guy may look at you funny but he'll at least be able to find your part!).

It should cost $5 or so, and it will look like this:


When you look at it, one of the 2 wires it has is larger than the other. Take this wire and bolt it under the post terminal on the alternator that also goes to the battery. This just leaves you with the one skinny wire. This wire goes to the accessory terminal on your ignition switch, even easier is to find the original alternator wire that energizes with the ignition and just connect it to that one. A word of warning here- this wire becomes energized when the alternator is spinning so you cannot wire it into the ignition circuit unless you have a manual cutoff, as when you turn off the key it keeps the circuit energized and the engine will keep running until you disconnect it. If you have no other way, you can run it through a light bulb which reduces the current but I did not need to for mine. Wired like this, it should not drain the battery at all.

[18vtx00]

When you say it is a 3 wire alternator, you mean it has an internal regulator and the plug on the side looks like this:


I converted mine a year ago and it works just fine, here is how you should modify yours-

First, go to NAPA or Autozone or wherever and get an "Alternator Harness Pigtail Connector" (that phrase is redundant, but some places call it a pigtail and some call it a connector and some use the term harness so if you call it that the parts guy may look at you funny but he'll at least be able to find your part!).

It should cost $5 or so, and it will look like this:


When you look at it, one of the 2 wires it has is larger than the other. Take this wire and bolt it under the post terminal on the alternator that also goes to the battery. This just leaves you with the one skinny wire. This wire goes to the accessory terminal on your ignition switch, even easier is to find the original alternator wire that energizes with the ignition and just connect it to that one. A word of warning here- this wire becomes energized when the alternator is spinning so you cannot wire it into the ignition circuit unless you have a manual cutoff, as when you turn off the key it keeps the circuit energized and the engine will keep running until you disconnect it. If you have no other way, you can run it through a light bulb which reduces the current but I did not need to for mine. Wired like this, it should not drain the battery at all.

Exactly how i wired it and used the same pigtail. I did have the full-field issue as well and would not shut off so had to use the accessory stud on the ignition switch.