Generator Problem???

Tom F OHIO

Tom F OHIO

Well-known member
Hi guys I need help as a rookie on these cars. My lights are very dim. I checked my battery this morning and it read 6.32 volts. I started the car, and the voltage kept dropping. Can someone help me on testing which wires on the generator to see what voltage is coming from it. I have three wires on it one in the back and two on the side. I am wondering if the generator or the battery is bad? Thanks for any advice... It's a 1952 Ford v8.
 
At around 1200-1500 RPM you should see at or near 7.5 volts at the armeture post on the back of your gen. These sytems don't produce at an idel .
 
I just got on here and earlier I put the two leads from my meter on the battery posts and reaved up the motor and the voltage went to 7.5 volts. I turned the motor off and left the leads on the battery and the voltage is dropping. Not sure what to do from here. Thanks pistonbroke for your post.
 
Tom F OHIO said:
I just got on here and earlier I put the two leads from my meter on the battery posts and reaved up the motor and the voltage went to 7.5 volts. I turned the motor off and left the leads on the battery and the voltage is dropping. Not sure what to do from here. Thanks pistonbroke for your post.
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yes, i've found that testing the entire charging system (generator/alternator, voltage regulator, grounds and wires) is more easily done with a multimeter using the battery posts of an engine running at more than 1500RPM. especially if it's a generator rather than an alternator.

for testing purposes, which terminals on the multimeter go to which terminals on the battery are of no concern, AFAIK. only the settings on the multimeter (DC, 20v) are important. one need only look at the absolute numbers on the multimeter for the result. about 15% more than the nominal voltage of the battery. i.e. for a 6v battery one should be looking for something around 6.9V.

at least that's been my experience.
 
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Thanks Huey. I also have one of those testers that you put the two cables on and push the button and on mine it says weak when putting the load on it
 
Check all your grounds, the old saying is clean,tight,bright, add another ground if you have to. My first car was a ‘50 sedan, my right blinker didn’t work I added a ground wire from the frame to the back of the light socket.
 
How did you fasten the ground wire to the socket? How would I add another ground wire. Sounds like maybe this is what I need. Thanks for the post...
 
if running a generator it would not surprise me if when reading the battery voltage with a multimeter AT IDLE that it would show something even possibly less than 6v. it would all depend on the RPMs at idle, which is different on every engine. as a generator as compared to an alternator is very inefficient at producing voltage at low RPMs compared to an alternator. which was one of the compelling reasons for the wholesale changeover to alternators from generators, in addition to more electrically powered accessories, in the 50-60's.

general rule is: to test the battery's condition or state of charge, the engine MUST NOT BE running, and to test the efficacy of the charging system components, distributor/alternator, voltage regulator, etc., the engine MUST BE running.

again...my understanding of it. :)
 
Tom F OHIO said:
I just got on here and earlier I put the two leads from my meter on the battery posts and reaved up the motor and the voltage went to 7.5 volts.

Thanks Huey. I also have one of those testers that you put the two cables on and push the button and on mine it says weak when putting the load on it.
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Replace the bad battery and concentrate on connections.
 
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