Generator Problem

Anonymous-0

Well-known Member
Here's one from the twilight zone. I had the generator for my AC-WD rebuilt, the shop rewired it for 12V, positive ground. On their test bench it puts out 14V. using their meter or mine. When I bring it home and mount it on the tractor I get nothing. Even disconnected from the tractor (it uses a one wire connection to the BAT terminal) measuring from the BAT terminal to ground on the generator itself, no output. I double checked and the battery is wired correctly - positive ground, and I proved that the generator is grounded to the frame. The tractor starts and runs fine, it just runs the battery down slowly.

How can it work on the test bench but not on the tractor, even disconnected from the tractor? Will a generator still work if its revolving in the wrong direction?

The rebuilder isn't interested in what happens after it leaves the shop in proper working order. Thanks in advance for your thoughts.
 
Wellllllll you say its a Generator, but when you talk about ONE WIRE CONNECTION TO THE BAT TERMINAL that sounds more like an Alternator. Next most alternators require Negative ground although they can be built for Positive HOWEVER if you hook one up in reverse you can damage it. Sooooooo I just dont know what to tell you sorry.

PS The post below, its a Generator NOT a Voltage Regulator that gets polarized.

John T
 
If john is correct, the RPM might be too low to excite the alternator.
Smaller pulley.
If one wire then it is difficult to make it work on low RPM. Jim
 
Since you had it "rewired for 12V" it sounds like a gen. There is no "positive ground" wiring. The gen. doesn't care which polarity it is. That's what polarizing is about. Does it have two posts on top- A and F ?
 
He has a single wire alternator. If it doesn't rev at a high speed it will not self excite the windings.
 
I did the same thing with a CA generator. However, it has two terminals. One for field and the other for battery. I need to change the drive pulley to a smaller diameter since it takes about 1600 rpm for it show charge on the amp gauge.
 
Regulators NEVER need polarizing. It's the GENERATOR that MAY need to be polarized, and it's often done (for convenience) by jumpering at the REGULATOR, which gets the job done at the GENERATOR.
 
If it a 6 volt generator, with a 12 volt regulator, it probably will put out 12 volts, but not much in the amps department. Same problem with one of our tractors. Have to put charger on overnight ocassionally to keep it up.
 
Thanks for the response, guys. To answer a couple of questions: its not an alternator, its the original generator that came with the tractor when it was new 60 years ago. It was rebuilt with a 12V regulator like Ray says. It produces full power on the test machine in the guy's shop, but no power on my tractor (disconnected) even at full throttle. There should be no difference.
 
Ground the field terminal at the generator. This causes the gen to put out. if it is not when grounded, make sure the gen itself is grounded and not insulated on paint. The regulator also must be grounded.
Reconnect the field to the regulator when done testing. Jim
 
Is the regulator mounted right on the generator? You need to have the battery wire connected to the regulator before it"s going to work. Then are you sure it"s not working? A volt meter would tell for sure.
 

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