Simple way to know if genny or regulator is bad?
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Freshman User
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Simple way to know if genny or regulator is bad?
My '51 is not charging. (6 volt/positive ground)
Anyone know a simple way to tell if it's the generator or regulator? I have a digital voltmeter and a 40-watt 1/2 ohm resistor, so I can measure voltage and current.
Thanks --
Anyone know a simple way to tell if it's the generator or regulator? I have a digital voltmeter and a 40-watt 1/2 ohm resistor, so I can measure voltage and current.
Thanks --
Fleet Owner
Joined: Jul 2004
Posts: 27,283
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From: NM
Hook up a wire to the Field terminal of the gen, long enough to reach into the cab. With the engine idling, ground the wire. Watch the ammeter; if it jumps to positive territory, and increases charging as you rev it, then the gen is putting out, the reg isn't working. You can do this to charge the battery with a dead reg, but not for too long as it puts the gen in full charge mode (at idle it may actually drain the battery, if the gen puts out less than battery voltage).
Don't use that 1/2-ohm!
Don't use that 1/2-ohm!
Senior User
Joined: Jan 2004
Posts: 298
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From: Albany NY
I don't think you want to do that. It could damage your regulator. Early Ford generators are shunt wound, internally grounded field. To excite the generator you must apply battery voltage (-6V) to the field terminal.
If you want to test the generator using the instrument panel ampmeter I think it is best to disconnect the voltage regulator. Jumper the ARM and FLD wires from the generator together. Start the engine and connect the ARM-FLD to the BAT wire. You should see a charge through the amp gage depending on the engine speed. Don't run the generator like this too long as it could overheat. Be careful not to inadvertently ground any of these wires since there is no fuse in the BAT lead. Be sure you are using the FLD wire/terminal from the generator and not the GND.
Craig
If you want to test the generator using the instrument panel ampmeter I think it is best to disconnect the voltage regulator. Jumper the ARM and FLD wires from the generator together. Start the engine and connect the ARM-FLD to the BAT wire. You should see a charge through the amp gage depending on the engine speed. Don't run the generator like this too long as it could overheat. Be careful not to inadvertently ground any of these wires since there is no fuse in the BAT lead. Be sure you are using the FLD wire/terminal from the generator and not the GND.
Craig
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I haven't tried the first method yet so I'll do as you recommend, Craig, and give it a shot. Thanks.
There's a guy on eBay selling alternator kits that provide a one-wire alternator and bracket setup for a 6 volt positive ground system. The advantage there would be that it charges the battery at idle, the disadvantage would be that it doesn't retain the stock look.
Any thoughts on changing to a 6v. pos ground alternator?
There's a guy on eBay selling alternator kits that provide a one-wire alternator and bracket setup for a 6 volt positive ground system. The advantage there would be that it charges the battery at idle, the disadvantage would be that it doesn't retain the stock look.
Any thoughts on changing to a 6v. pos ground alternator?
Fleet Owner
Joined: Jul 2004
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From: NM
An alternator would be good. Why not go 12v tho?
Dmptrkr, I think you could be right. The info I had was from someone with an earlier truck. I looked at the '48-49 F-1 wiring diagram on MacVP's site (http://www.vanpeltsales.com/FH_web/F...48-49truck.jpg) and it looks there like the reg does provide power to the field, and it's internally grounded. Thanks for catching that!
Dmptrkr, I think you could be right. The info I had was from someone with an earlier truck. I looked at the '48-49 F-1 wiring diagram on MacVP's site (http://www.vanpeltsales.com/FH_web/F...48-49truck.jpg) and it looks there like the reg does provide power to the field, and it's internally grounded. Thanks for catching that!
Logistics Pro
Joined: Oct 2002
Posts: 4,489
Likes: 5
From: Valley Center, CA
Have you tried polarizing the generator yet? I always try to do the easiet least expensive things first. 
Jag
Jag
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So I used the recommended method and found that my generator is putting out plenty of current, as evidenced by the smoking insulation on the jumper wire when I gunned the engine. Yep, the dashboard ammeter jumped to the right, first time I've ever seen that on this truck.
I cleaned the regulator contacts to no avail, so I guess it's new regulator time. Thanks for the suggestions, everyone.
chico
I cleaned the regulator contacts to no avail, so I guess it's new regulator time. Thanks for the suggestions, everyone.
chico
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Logistics Pro
Joined: Oct 2002
Posts: 4,489
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From: Valley Center, CA
Yo Chico! If the generator is not polarized, you will get zilch through the regulator. Did you polarize it? If not, we can lead you thru it. It takes one minute. 
If it is not polarized you can replace the regulator as many times as you want and still get no juice. 
Jag
If it is not polarized you can replace the regulator as many times as you want and still get no juice. Jag
