Generator wired correctly???

38convsedan

38convsedan

Senior Member
I’m sure this has been asked and answered:

8BA with 1950 Truck generator on my 38 Conv Sedan.

I currently have back of generator ammeter post to ammeter on regulator.

F on generator to field on regulator.

G on generator to ground.

Hot wire from fuse block to battery on regulator.

Is this correct?.

I just saw a 1950 truck wiring diagram showing all of the above plus G on generator also connected to battery on regulator…

I am having charging issues (see Erratic Generator post from a few days ago)
 
Yes , you have it wired correctly. ( Note that the correct terminology is "armature" rather than ammeter for your generator output wire). The generator "G" ground wire should never be connected to Battery on the regulator...that's going to be big trouble and is an obvious misprint.



Terry


,,,Just read your Erratic Gen post. Do you have a voltmeter you can hook up to see what voltage you have when running the engine, turning on lights, revving the engine, etc? That would really help.
 
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Regulators used to have a rubber bushing mounting to isolate the unit from the vibration of the car in operation. You can't really hear it but the voltage regulator has a buzz to it due to the rapidly opening and closing points. They ran a ground wire from the generator to a special ground terminal on the side of the regulator. Later replacements are hard mounted and have no ground terminal.
 
I also had the erratic ammeter on my 6 volt positive grd system with 2 brush generator and 3 coil voltage regulator. I ran a wire from the generator frame to the regulator frame with the wire terminals being soldered to the wire. Using a digital ohm meter check the resistance between the frame of the generator and the frame of the regulator. Should be zero. A 0.1 ohm resistance caused the erratic ammeter in my system. Connections must be CLEAN AND TIGHT.
 
Did your ammeter stop working after a few minutes? That is what’s happening to mine.
Seems to work at cold start, then begin bouncing around after a few minutes, then the gauge stops in middle. Will show discharge when lights are turned on, then returns to middle with no positive charge at that point.
It behaves same way with a second voltage regulator
Could a wiring short somewhere cause this issue?
 
I offered a solution to your problem in another thread that you started regarding your generator - regulator. I think the generator is putting out less than 7.2 volts and that you need the ground wire that I outlined above. Just to be sure, touch the field wire disconnected from the regulator to the battery terminal on the regulator to polarize the generator if you have not already done so. Don’t give up - report back.
 
Do you have any starting issues after a ride at night . Do you have any non original lights hooked into the headlight system? It sounds like the system is operating normal aside from the bounce. The generator will not put out until its needed . If you have a charged battery and start your car , it should show a discharge until you bring the motor up off idle . In mine it takes about 1200-1500 rpm or 30 mph in 2nd .
 
Connected wire from generator casing bolt to regulator frame.
Had no effect.
Gauge behaved as before: worked normally showing charge as appropriate, then began moving erratically, then retreated to center with zero movement. This all takes place in a span of about 2-3 minutes. Gauge will remain this way until next cold start.
Thoughts??
 
You did speed the engine up above idle while testing with the meter, correct? If so, it is not charging properly, if at all.



My next test would be to hook the voltmeter to the Armature terminal of the generator (and ground the other meter lead to a good ground) and run the engine at a fast idle of at least 1000 rpm. If it doesn't charge at least 6.6v I would run a wire from battery power (right from the battery is fine) and touch it to the Field terminal of the generator while the engine is running at fast idle. The voltage will come up if the generator is working. Don't shut off the engine with the wire from the battery still touching the field terminal.



This test will tell you if the gen is ok or the problem is elsewhere.


Please note that all tests are made with the engine sped up...the gen will not charge at idle even if it's ok.



Terry
 
Use a digital ohm to measure resistance between generator frame and regulator frame for zero ohms - a 0.1 ohm will make the ammeter erratic. An analog meter is not sensitive enough for this test.

Use the test that Cadillac512 outlined for you. If the generator puts out voltage per Cadillac512 test, then go to the field control in the regulator and connect your engine analyzer to the Bat terminal and ground and adjust the stationary terminal for the spring to increase the tension of the spring until you get at least 7.2 volts running the engine at 1500 rpm or more.
 
At fast idle, with gauge again in dead position after bouncing around, generator shows about 5 volts with voltmeter connected to generator armature and a good ground.

Do I leave voltmeter connect as above (armature and ground) when performing the second test, battery to field?
 
I did get 0.1 with digital ohm gauge between generator frame and regulator frame.
How do I correct this to achieve 0.0?
 
38convsedan said:
At fast idle, with gauge again in dead position after bouncing around, generator shows about 5 volts with voltmeter connected to generator armature and a good ground.

Do I leave voltmeter connect as above (armature and ground) when performing the second test, battery to field?
Click to expand...




Yes sir...same voltmeter connection. Test with engine sped up above idle.


As for the .1 ohm reistance, the way to get 0 is a larger wire from gen ground to regulator ground with clean bright connections at each end. This may help the erratic gauge but is not your main charging problem.
 
To get rid of the 0.1 ohm reisitence all terminals must be CLEAN AND TIGHT!!!!. Start by soldering the terminals to the 16ga wire with rosin core solder. At the regulator frame, run a flat file across the terminal on the 16ga wire to clean it and use a starr washer between the regulator frame and the terminal you just cleaned and tighten it. The other end at the generator, also solder a terminal on the 16ga wire tha comes from the regulator frame, clean with flat of the file. If you do not have a ground post on the side of the generator, but put the terminal under one of the long bolts that hold the generator together. Clean under that bolt head and if you can get the bolt out (single carb) run it across a wire brush on your grinder and run the flat of the file across the back plate that the bolt pulls against. You can use your digital ohm meter to check each connection by itself and then check both connections going from the generator frame to the regulator frame. Time and patience Your goal is 0.0 ohms.

As to the output of the generator, connect your voltmeter negative to the ARM terminal on the regulator and the positive to ground. Assuming you have 6 volt positive ground. Remove the field terminal, start motor and with one hand on the throttle and the other hand holding the field wire, run the engine to about 1500 rpm and while doing so, momentarily touch the field wire to the ARM terminal on the regulator - voltmeter should jump up over 7 - 8 volts. Do not hold it there - you can burn up the generator. This is just a very brief test at more than a fast idle. If the generator flunks this test, then remove the generator and either take it to a shop or dive into it your self, check out all of the internal connections for clean and tight, use fine sandpaper on the commutator, and perhaps replace brushes. A shop can check the armature for shorts and the field coils for open circuit. You can check the field coils for open circuit by removing the field wire at the regulator and connecting an ohmmeter from the field wire to generator case. Should show resistance. We will be interested in what you find. Report back!!
 
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Generator show just over 7 volts on voltmeter on fast idle while amp gauge is dead center (after doing its “normal” shows-charge-then-bouncing routine.)

Could the regulator be at fault? Is it allowing battery to charge briefly each time, then closing and preventing battery to charge, even though generator is producing over 7 volts at voltmeter?
 
38convsedan said:
Generator show just over 7 volts on voltmeter on fast idle while amp gauge is dead center (after doing its “normal” shows-charge-then-bouncing routine.)

Could the regulator be at fault? Is it allowing battery to charge briefly each time, then closing and preventing battery to charge, even though generator is producing over 7 volts at voltmeter?
Click to expand...


Ok, the generator is charging enough to actuate the regulator. Yes, it is possibly a regulator problem...fairly likely in my opinion.



Terry
 
Reread my post #15. Disconnect the field wire at the regulator, start the engine and with one hand on the throttle and the other holding the field wire, speed the engine to about 1500 rpm and then touch the field wire to the ARM terminal on the regulator - your analog voltmeter should read well over 7 volts. This test takes the regulator out of consideration and determine the ability of the generator to put out sufficient voltage. Run the test as outlined and report back. I am trying to narrow the culprit in your chaging system system.

Did you obtain zero ohms on the ground wire connecting the frames of the generator and regulator?.
 
Ok Bill
Just ran your test.
Voltmeter connected to armature on regulator, other wire to ground.
Touched field wire to armature on regulator while revving engine.
Voltmeter read over 7 volts.
 
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