The Stovebolt Site Forums The Shop Area The Electrical Bay 3 wire alternator - how to wire it in my 59 Chevy

Hello again...I am having difficulty wiring the alternator and getting it to charge. Alternator checked and good.

1. Connected 10 ga wire from alt to battery
2. Connected 14 ga wire from #1 to ignition
3. Connected 14 ga wire from #2 to starter

Not charging...am I supposed to disconnect the original voltage meter completely?

Anyone got any suggestions? Searched the archives but not finding the answer so I figured I would post. Thanks, Steve

Hy bigdog58, have you put a voltmeter on the battery, how do you know it's not charging? The way you describe how you wired it you have eliminated the ammeter from the charging part of the circuit. When I replace a generator with an alternator I remove the armature and battery wires from the old generator regulator, and wire them together and insulate them. Then you can use the old armature wire to attach to the alternator output terminal, that way your ammeter still reflects the charging/discharging of the battery. I can't remember for sure which terminal is number one and which one is number two on the plug, but I think number one can be looped back to the output terminal, and number two can be connected to the accessory side of the igniton switch, do not connect it to the ignition side of the switch, or once the engine starts you will not be able to shut it off. I may have those terminal numbers backwards, but if I do someone will be along to correct me, hope that helps.

If it's an internally regulated Delco alternator, one of the small wires is the field excitation and the other is the regulator sensing wire. I believe field excitation is the #1 wire. Typically this is connected through an idiot light to a 12v source that is hot when the ignition is on and disconnected when the iginition is off. The regulator sensing wire is connected somwhere in the system that it can measure the voltage and adjust for voltage drops to make sure the system is getting full power. Typically this is near the battery supply to the fuse box, although some just connect it to the alternator output. It is important that the excitation wire be disconnected when the ignition is off or the alternator will feed back through the idiot light and power whatever its connected to. That's why 3B suggested connecting it to the accessory position of the switch.

To learn a lot about this in a short time, I recommend the MAD Electrical Tech Section .

regards,
Leon

Thanks guys...I maybe have the wire on the wrong side of the ignition switch. I will try an alternate source. The other issue is what to do with the wires going to the original voltage regulator. Any suggestions? Once I turn key on the amp gauge in cluster starts to the left...then when engine running it moves further left when I know it should be going right to CHARGE.

Help with that issue if you guys have experienced the same situation.

Thanks, Steve in Idaho

Hy bigdog58, I told you in my first post on this subject how to use two of the wires off of the old voltage regulator, and bring the ammeter back into the circuit. As for the field wire, you can just disconnect it when you remove the regulator, it only goes from the regulator out to the generator, I usually tap into it for the field excitation wire in my alternator conversions, hope that helps.

Thanks again 3B and Leon... I managed to wire it up and test to find that I have 15+ volts charging so I know it's charging...I just need to disconnect the old voltage regulator and complete the system so the amp meter works on the dsah...fortunately for me it is at paint now getting painted and will finish it when I get it back next week.

3B..you said "When I replace a generator with an alternator I remove the armature and battery wires from the old generator regulator, and wire them together and insulate them. Then you can use the old armature wire to attach to the alternator output terminal, that way your ammeter still reflects the charging/discharging of the battery." So, am I connecting the battery wire from alternator to the battery wire from where it attaches to the old regulator? I currently have it attached to the battery itself. Amp meter on dash reads the wrong way but it is charging.

Thanks again guys for the help. Steve in Idaho

One more thing...so, just get rid of the old field wire I guess?

Hy bigdog58, yes you can connect the alternator output wire to the battery wire from the old generator regulator, you can splice them together, but if you leave the terminal on the wire and bolt them together, make sure you insulate the connection very well. There is no need to remove the field wire, just tape the ends out of sight, hope that helps.