Hello everyone, I have a 30 amp generator on my 64 ford pickup and it will only do 8 amps maximum when i give the field full battery voltage for a second. I took it all apart and could not find any shorts or opens in the armeture. All my connections were clean and tight. My field coil resistence is about 6.5 ohms, is this too much? I tested a 6 volt gen and its field coil read 3.0 so i figured the double amount of windings in my 12v gen would make the resistence slighty higher. Any guru's out there that know some more tests i can do to this thing before i go get another one. I know it isnt my regualator because applying full battery voltage to the field for a second would rule out regulator problems. Oh yeah, no i dont want to put an alternator on it, i like the original look of the generator. Thanks for any and all help.

 

Do you have a wiring diagram? The reason I ask is I thought most of the old generators grounded the field for full output? Of course you have to have the output terminal connected to the battery +.

 

How did you measure the 8 amp output? Dash gauge or a real meter setup. Did your output voltage rise when you gave it full field? Did you measure the voltage at the battery or at the gen output? Is the regulator current limiter set correctly? I would investigate the current limiter setup. Most people don't know about this anymore. An alternator is self limiting for current, a generator will burn itself up if not limited so the regulator has a current limiter coil. It is the one with the heavy gauge wire winding.

 

Thanks for the reply's guys, I will explain how a tested the generator as best i can. I used a length of 10ga. wire from the armature terminal to the battery positive with a amp meter installed in the wire. I then used a jumper from the armature terminal to the field terminal to give it full battery voltage for maximum output test. I then started the truck, set the idle at 2000rpm's and then proceded to connect my 10ga, wire to the battery for no more than 5 seconds at a time as not to burn up or overheat the generator. I did not use a volt meter during this test but when i had the generator connected to the regulator it would do 4 amps and eventualy the battery voltage would get to 15.5, this would take about 10 mins of fast idling to accomplish and if you turned on any accessories it would slowly kill the battery. When i had the regulator connected i had the amp meter connected between the battery terminal on the regulator and the battery. All my grounds were good as i checked them and i even have a battery cable connected to the generator bracket. I am also sure it is wired correctly. Hope this helps!

 

I have looked all around, and can't prove my grounding the field theory, though I know some of them where that way. Here's a diagram I found for a 64 f100 with a generator.

http://www.tocmp.com/tOCMP/wiring/19...964_07_gif.htm

What I think is interesting is the armature terminal(we are assuming "A" is the armature) is not connected directly to the battery, but goes through the regulator first. This may only have to do with bringing the generator "online" after the engine is turning though(that's a guess).

I think one thing you are assuming is that the field windings are terminated with one end on the "F" terminal of the generator, and the other end tied internally to the case(ground) of the generator. If this is true, then I believe you are correct in putting 12 volts on the field. But, if you take your ohmmeter and read between the "F" and one of the other terminals on the generator, and actually get a reading, that means the field windings are connnected in some other way, and you may need to re-think how to hook this thing up to test it. I wish I knew exactly how it was wired inside.

 

Franklin, The generator that you ground the field for is the style where the positive side of the field is connected to the armature inside the generator and the negative side is connected to a terminal on the regulator. The difference being mine controls the positive side of the field and not the negative. In the diagram you found on my generator wiring the g on the gen is the negative side of the field. I have reason to believe after all this testing that it is my armature shorting. I emailed a guy that has been rebuilding generators and such for over 25 years and he said its possible to have what is called a "flying short" in which it doesnt short until it is spinning. To test this theory i spun my generator with a 1400rpm electric drill and checked between the armature and ground and i would sometimes see a short for just a split second and seemed to lessen as i increased the speed on the drill. I think the flying short would have an effect on how well the field gets energized and cause low output. I decided to purchase a rebuilt unit from napa. Thank you for you help i appreciate it.

 

Also, the reason the armatue wire goes through the regulator is at idle and low speeds the generator must be cut out of the circuit to prevent it from draining the battery. A generator is actully an electric motor in reverse so at idle it will try and run as motor and drain the battery so the cutout relay in the regulator cuts it out of the circuit.

 

That sounds logical.

 

I have recently been researching how to polarize a generator system. It said that under no conditions should you short out the field terminal to the bat terminal. It says to momentarily short or jump a wire from the Batt to the Gen/Arm posts only.I will test this today as I have a new toy(67 D4 Cat) with a 6 volt system used for starting and lights only.How do you read the amp output with a cheap electric tester?
"bowties in the rearview mirror"

 

On most cheap meters you can't. On others, you usually have to unplug one of the leads and plug it into another terminal on the meter. Then turn the selector on the meter to it's highest amp scale. But even on a good meter, these are only good for about 10 amps.

One way that does work even with a cheap meter, is to read the voltage on the battery with the engine off(to get an idea what the meter will read) and then read the battery voltage again with the engine running.

The voltage will be higher if the gen(or alt) is working with the engine running. You will not be able to tell the amperage output of the gen by reading the voltage on the battery, but you can see if it's keeping up. That will give you somewhat of an idea it's working.

So get a baseline voltage with the engine off, then read the voltage with the engine running. If you have to rev the engine a little bit to get a higher volt reading, then you know the gen is not putting out much at lower rpms(which is normal). Then if you really want to test it, turn on every electrical load you have, and then read the voltage. If you when you rev the engine, the voltage is still higher than it was when the engine was off, then you know the gen is still keeping up with room to spare. If the voltage is the same as it was with the engine off, you know the gen is barely keeping up. If the voltage is actually lower than when the engine was off, then you know the gen is not keeping up with the demand.

 

Franklin2,I got it all hooked up and polarized and checked the voltage as you described at the bottom of your post.The generator is just keeping up with the lights on so that is all I really need .My delco remy voltage regulator does not indicate which terminal is the Armature or feild,the Batt is obvious.I guessed at which one was the arm,is there any way to tell by looking at them as to which is which? Thanks for the help. PS -I think I fried my tester!
"bowties in the rearview mirror"

 

Go to this site and look at some of the old chevy manuals. They may have something on the regulator you can use.

http://www.oldcarmanual.com/