Generator Field Wiring
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Laughing Gas
Joined: Oct 2012
Posts: 831
Likes: 7
From: Milford, Michigan
Generator Field Wiring
I am rewiring my F2 and converting it to 12V neg ground. I am wiring the generator at the moment and I need to know what gauge wire should I use for the field connection on the generator to the field connection on the voltage regulator. I am using a 10 ga wire for the armature wire but am not sure what size to use for the ground and field. I read somewhere that the field coils only draw about 3 amps but I am looking for confirmation. Thanks.
Fleet Owner
Joined: Jul 2004
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From: NM
No, it should be the same as the Armature wire. Theoretically the generator is grounded thru the mounts, but for best performance, it should be grounded to the regulator chassis. I'd go at least #12.
Is this a stock 6v generator running with a 12v regulator? Or did you replace the field coils with 12v pieces? If it's a 6v unit, from what I've heard the most you can get out of it is about 25-30 amps at 12v. Your #10 armature wire is plenty hefty.
Is this a stock 6v generator running with a 12v regulator? Or did you replace the field coils with 12v pieces? If it's a 6v unit, from what I've heard the most you can get out of it is about 25-30 amps at 12v. Your #10 armature wire is plenty hefty.
Tuned
Joined: Oct 2005
Posts: 485
Likes: 32
From: Northern OR
The 16 gauge would be fine for the ground connection. That connection is meant to insure a good "return path" for the field circuit which originates in the regulator. Charging current is not carried by this wire as long as the battery is grounded properly with the engine.
Fleet Owner
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From: NM
Look at the circuit above; the armature is grounded thru the gen case. Armature current = charging current.
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Tuned
Joined: Oct 2005
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From: Northern OR
He's asking about the ground wire for the field circuit. That wire is shown at the top of the diagram and runs from the "G" terminal on the generator to the frame of the regulator. This wire is not to be confused with the "return" for the armature current which comes back from the battery to engine ground, and then through the generator frame to the grounded brush. That circuit is to the left side of the diagram.
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Thread Starter
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Laughing Gas
Joined: Oct 2012
Posts: 831
Likes: 7
From: Milford, Michigan
He's asking about the ground wire for the field circuit. That wire is shown at the top of the diagram and runs from the "G" terminal on the generator to the frame of the regulator. This wire is not to be confused with the "return" for the armature current which comes back from the battery to engine ground, and then through the generator frame to the grounded brush. That circuit is to the left side of the diagram.
Post Fiend
Joined: Apr 2002
Posts: 19,311
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From: Waterloo, Iowa
Wait, what?
I was always taught that one of the advantages of the 12 volt system over the 6, was lighter gauge wiring and cables can be used throughout, due to decreased current draw. Therefore, no wiring need be changed in a 6 to 12 volt conversion because of this.
I was always taught that one of the advantages of the 12 volt system over the 6, was lighter gauge wiring and cables can be used throughout, due to decreased current draw. Therefore, no wiring need be changed in a 6 to 12 volt conversion because of this.
Fleet Owner
Joined: Jul 2004
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From: NM
The field coils are a fixed resistance. V/R = I
If you double the voltage, you double the current. But since he has a 12v generator, with field coils designed for 12v from the get-go, it's a moot point. I made that comment assuming that he was using a 6v generator.
When talking about lights, the wattage (= V x I) is constant. So I is cut in half at twice the voltage.
If you double the voltage, you double the current. But since he has a 12v generator, with field coils designed for 12v from the get-go, it's a moot point. I made that comment assuming that he was using a 6v generator.
When talking about lights, the wattage (= V x I) is constant. So I is cut in half at twice the voltage.
Thread Starter
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Laughing Gas
Joined: Oct 2012
Posts: 831
Likes: 7
From: Milford, Michigan
So at 12V, you push half the amps through the wire, so it can smaller.
For more than you care to read on the subject, courtesy of Google:
http://www.ebtx.com/mech/ampvolt.htm
Hopefully, others will get as much info out of this discussion as I did. This forum rocks!!
Tuned
Joined: Oct 2005
Posts: 485
Likes: 32
From: Northern OR
Ross is correct on the wire size. I went out and looked at my '52 and the ground wire going to the regulator is heavier gauge than the field wire. I don't believe these trucks had a ground strap from the body to the frame (or engine) anywhere, so that's the reason the ground wire is heavier - it serves the same purpose as the ground straps you see from the firewall to the engine on other cars. It's not only the return path for the field circuit, but also for the voltage limiter and cut-out coils in the regulator. In addition, that wire serves as the return path for all electrical devices that are grounded to the body. The return for current going directly to charge the battery comes back to the generator through the battery ground which connects to the engine. I was wrong about the ground terminal being labeled "G" - it's actually "GND" and field is "FLD." There should be just (3) terminals on the generator. It shouldn't be necessary to run another ground wire to connect with the battery ground cable. Sorry if I confused the issue. - Bob