Page 1 of 3 123 LastLast
Results 1 to 10 of 22

Thread: What's going on with my Generator?

  1. #1
    Member Nemo von Klepper's Avatar
    Join Date
    Jan 2013
    Location
    Portland, OR
    Posts
    98

    What's going on with my Generator?

    This is my first time messing around with a generator, so essentially my first rodeo. The regulator is new from KW and the generator was just rebuilt, all 12v.
    It doesn't seem to be charging:
    Volt meter with the engine at about 1000rpms reads 12.2 and gradually sinks to 11.9. I was expecting somewhere around 14. I made sure the polarity was set, momentarily jumping the battery to the armature tab on the regulator (type A generator). I got a spark, a hum and the generator turned for a second the same direction as the engine. I considered this to be a good sign that the generator is in fact good. I noticed right before I turned the engine on that the amp meter which has been stubbornly been at zero was now marking at -50 amps. After I turned the engine on, the amp meter went back to just on the positive side of zero but I was only able to read 12v with the volt meter.

    Next I took the lid off of the regulator. Everything there looks good, shiny and new.

    I'm not sure what to do next.

  2. #2
    Senior Member
    Join Date
    Jan 2015
    Location
    E OK
    Posts
    371
    My generator experience is pretty limited and I don’t know at what engine RPM these generators need to produce power. I know on applications I am familiar with 1,000 rpm isn’t likely to get the generator generating. Usually 1200-1500 to get them started and they fall off line at 800-1000 but there are variables that can make up the difference. Most notable is the pulley sizes.
    Jeff
    '51 CJ3A
    '47 CJ2A

  3. #3
    Member Nemo von Klepper's Avatar
    Join Date
    Jan 2013
    Location
    Portland, OR
    Posts
    98
    Ok, so the old timers are probably rolling their eyes about now, "Here we go with the 'My generator isn't charging' conversation again!"
    Yup, you said it. A brief search over the internet yields many, many conversations on this subject, almost exactly like my conversation. So tomorrow I'll try it again at a much higher RPM. I expect it'll be fine, which will be a relief since I decided to rebuild the generator instead of an alternator at a likely higher cost. At least someone gave me the generator core. I want to get this rig on the road this summer so I'm chomping at the bit to move on to getting the brakes adjusted and start rolling.

  4. #4
    Super Moderator bmorgil's Avatar
    Join Date
    Dec 2018
    Location
    Northwestern Ohio
    Posts
    2,787
    We need LarrBeard to pipe in here but, I would be looking at the regulator. It might need adjustment.

  5. #5
    Super Moderator LarrBeard's Avatar
    Join Date
    Nov 2014
    Location
    Ft. Wayne, IN
    Posts
    2,265

    What’s wrong with my generator?

    Quote Originally Posted by bmorgil View Post
    We need LarrBeard to pipe in here but, I would be looking at the regulator. It might need adjustment.
    Herr von Klepper:

    We “Old Guys” don’t mind answering the “Why isn’t my battery charging; what’s wrong with my generator?” questions. It makes us feel like we’re still important! Here is more than you probably want to know....

    Disconnect the Field lead from the generator (at the generator case), that would generally be the smaller of the two terminals. Since you have a rebuilt – donated – generator, make sure you have Field and Armature figured out correctly.

    You are going to ground the field terminal; by doing this you are going to bypass all of the relays and resistors in the voltage regulator and put the generator at close to full output. The most conservative way is to make up a test lamp (12-volt tail light bulb), hook one lead to a good frame ground and with the motor running, connect the other to the Field terminal. This allows a bunch of current to flow through the Field windings. The bulb should light up (it should be pretty bright) and you should get a + reading on the ammeter. This connects the light back to the battery through the Field windings and brushes, but limits the current through the Field coils to what the lamp would normally draw. (An 1141 bulb will draw about an amp or a little more – it might not bring the generator to full output, but it will give you an idea if things are alive).

    The other less conservative way is to just take a clip lead and ground the Field terminal directly. This will put a LOT of current through the Field windings, so do not hold it too long or magic smoke will come out of somewhere, usually the insulation of the clip lead. This should put you at a hearty + reading on the ammeter – full output of the generator. Really old timers called this “full fielding” a generator.

    This should give you an idea of your generator’s ability to turn RPM’s into amps. If you don’t get amps with these tests, I suspect an issue with the generator. If these checks give you amps, I’d replace the regulator. Defective (but new) voltage regulators are rare but not unheard of. Adjusting one is almost never necessary and it takes a lot more “stuff” that most of us want to fool with these days.

    Good luck, let us know what you find – and we’ve not seen any pictures of the project lately.

  6. #6
    Member Nemo von Klepper's Avatar
    Join Date
    Jan 2013
    Location
    Portland, OR
    Posts
    98
    Well, anymore anyone is an old timer if they learned to drive on a stick, type on a typewriter, dial a rotary phone, etc.

    3F55E669-D28F-4325-AAD5-7E4326555886.jpg

    I’ll take a look today when I need a break at work. Thanks for the input.

  7. #7
    Member Nemo von Klepper's Avatar
    Join Date
    Jan 2013
    Location
    Portland, OR
    Posts
    98
    Well, tear it all! Yesterday afternoon when I went to try the jeep, the battery was completely flat with no obvious cause: headlights, blinkers, etc. It was too flat to even jump it by myself, so I've had it on the charger all night with the negative post disconnected.

    Not sure what's going on now. Before I tried to re-polarize the gen the day before it was seemingly not charging, might be user error, but it also wasn't draining the battery. Not sure at this time if it's related, I might have just run the battery down too much when I was messing with it before.

    Before I reconnect the battery, I'm going to check for an amp draw between the negative post and the cable. If that exists, I'll try to isolate the source: Check for continuity between the positive post on the battery and the field or armature posts on the gen, or voltage at the gen with the engine off. If those exist, then I'll check for continuity between the battery terminal and the field or armature terminals on the regulator.

    My theory here is that one of the contacts on the regulator maybe stuck, creating an electro magnetic field in the gen., but then I don't know much about generators.

  8. #8
    Member Nemo von Klepper's Avatar
    Join Date
    Jan 2013
    Location
    Portland, OR
    Posts
    98
    Ok, so now it might be charging, but my ammeter is going crazy. Related but separate issue so posting in a new thread.

  9. #9
    Super Moderator bmorgil's Avatar
    Join Date
    Dec 2018
    Location
    Northwestern Ohio
    Posts
    2,787
    Nemo it does sound like the regulator is having fits. Larry might jump in here with a circuit diagram. It sounds like the contacts in the cutout are having an issue.

    Here is a good Voltage regulator 101.

    http://www.secondchancegarage.com/public/83.cfm
    Last edited by bmorgil; 07-04-2022 at 07:09 AM.

  10. #10
    Super Moderator LarrBeard's Avatar
    Join Date
    Nov 2014
    Location
    Ft. Wayne, IN
    Posts
    2,265
    “OH, tear it all…”.. WOW – we’re not used to such refined phrases of frustration here. We’re more accustomed to SHYTE – or its’ equivalent.

    You commented that the system was charging, but the ammeter was going crazy.

    The link BMorgil gave you is a good description of what is happening in the regulator. Since the system is not showing a nigh current discharge when you shut off the Jeep, we can throw the “circuit breaker/reverse current relay” off the list of culprits, leaving us the over-voltage and over-current relays.

    Now, on my truck, after a prolonged cranking period, the ammeter starts out at about a 30-amp charge, a steady value. After a bit, the ammeter does indeed go crazy. In my case it is because of the action of the over-voltage relay. After the cranking, the battery voltage is low, so the over-voltage relay sets the generator to full charge – the 30 or so amp reading. That is below the trip point of the over-current relay, so that relay stays out of the picture all of the time on my truck.

    AS the battery starts to come up to a voltage that looks like it is charged, the over-voltage relay opens and connects a resistor in series with the field coil. That drops the charge current considerably – but since the battery isn’t really charged yet, its’ terminal voltage drops. That causes the over-voltage relay to close – removing the resistor from the field circuit and raises the charge rate again. Initially, the battery does not respond to the high charge current instantly – it takes a slug of energy (current over a period of time) to raise it up. The high charge rate raises the battery voltage and the cycle repeats until the battery really does come up to charge. During this period (on the truck maybe 10 or 15 seconds) the ammeter is going bonkers.

    Once it does that, the battery’s charge is just being “tweaked” and it settles down to a constant low-rate (maybe 5 amp) charge rate. At this point the overvoltage relay is actually buzzing like a doorbell buzzer.. many times a second (One of these day I may look just to see how fast it is .. Hmmm).

    You can take the cover off the regulator and feel the frames of the relay coils to see which one is going nutso on you – you can probably see it as well. Why is this happening? Troubleshooting by internet is risky … but:

    A. If, for some reason the resistor that regulates field current via the over-voltage relay has opened, the regulator is in an ON-OFF mode, full charge or no charge. Simple answer – defective regulator – it ain’t worth trying to fix.
    B. If your battery is deeply discharged, it could be getting into an interaction with both the over-current and over-voltage relay circuits.

    We can way overthink these things and as a sparktrician and tinkerer I’ll piddle more with things like this that I should.

    Make sure you have a good charge on the battery. If it tops off on the charger at 14-or so volts and still has issues in the Jeep, change the regulator.

    Let us know what happens – and Happy Independence Day!

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •