Cj3a Smoking From Generator

Discussion in 'Flat Fender Tech' started by haighfam, Jun 15, 2017.

  1. Jun 15, 2017
    haighfam

    haighfam Member

    Paradise, CA
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    Just got my 3A back from Colorado. Needed a new battery. Old battery seemed to have reversed polarity. Put in new battery 12V. Has been converted to 12V by PO. Started and ran great. Moved it around the yard. After about an hour noticed smoke emitting from under the hood. Immediately disconnected the battery. Generator and voltage regulator were hot. Suggestions as what to look for? Did not have this problem when it went to Colorado, but was not driven and battery was dead, had to pull start it to get it on trailer.
     
  2. Jun 15, 2017
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member Sponsor

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    Batteries do not reverse polarity, not unless they've been drained right down to absolutely nothing.

    You've obviously got something major wrong going on- iI suspect somehow it's your genny that's become reversed. Get it running & check the polarity of the voltage to ground.

    H.
     
  3. Jun 15, 2017
    haighfam

    haighfam Member

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    I am sure battery was drained to nothing. How do I reverse the polarity of the generator?
     
  4. Jun 16, 2017
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member Sponsor

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    First you need to verify what the issue is- get it running, check the polarity of the voltage & voltage level, no point trying to fix the problem until you know what the problem is.

    H.
     
  5. Jun 16, 2017
    PeteL

    PeteL Member Sponsor

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    Howard is right. Think first, then act.

    "Flashing" or polarizing a generator/regulator combo is extremely simple. But the precise method depends on the make and model of the particular generator in your Jeep.

    But first, spend a few minutes under the hood with a voltmeter and a flashlight. For example, is there a shorted wire? What is the resting voltage of the battery? Voltage while idling? Etcetera.
     
  6. Jun 16, 2017
    Walt Couch

    Walt Couch sidehill Cordele, Ga. Sponsor

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    Was any body messing with your jeep while in Colorado? As said, It could not have done this by itself. Someone put battery charger on backwards and reverse charge battery? POS/NEG regulator does not care which polarity is used. Gen has to be polarized but will charge either way.
     
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  7. Jun 16, 2017
    haighfam

    haighfam Member

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    It sat in son's garage and was only driven 2-3 times in 2 years. Battery was dead 2 weeks ago and he charged it to move it. He said it ran good. I think he charged it right, but who knows. Battery was 8 years old and wouldn't hold a charge. We had to pull start it to get it up on the trailer. Will investigate as PeteL suggested and post my results.
     
  8. Jun 16, 2017
    Daryl

    Daryl Sponsor Sponsor

    Bonney Lake, WA
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    I think I would put in a known fully charged battery to start with. Trying to charge a flat dead battery could have simply overworked your generator. My grampa used to say to never jump start a fully dead battery. Maybe he was right.
     
  9. Jun 16, 2017
    PeteL

    PeteL Member Sponsor

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    New alternators now come with a warning that charging a dead battery will kill them.
    That said, I've done it many times in the past.

    But yes, start with a known-good battery, for sure.
     
  10. Jun 16, 2017
    Glenn

    Glenn Kinda grumpy old man Staff Member Sponsor

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    Does the Jeep have an amp meter? Maybe a regulator contact stuck?
     
  11. Jun 16, 2017
    haighfam

    haighfam Member

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    I put a new fully charged battery in it before the smoking incident. Old battery would not pass a load test.
     
  12. Jun 16, 2017
    haighfam

    haighfam Member

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    I started it this evening to run some tests. It does have an amp meter, and while idling was reading 8-10 amps on the positive side. Yesterday before the smoking incident while idling it was reading about 5 amps to the negative side. Does not seem to be charging. Idled for 20 minutes and the battery voltage across the terminals dropped from 12.21v to 12.09v. I have an FSM, will go through all checks for generator and voltage regulator and report my findings. Will investigate the regulator contacts and dress them per FSM. Good news is it runs good on the new battery so after sitting for 2 years no other issues than this are apparent.
     
  13. Jun 16, 2017
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member Sponsor

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    A genny won't charge at idle, you have to get the rpms up too 1100-1200 rpm for full charging voltage to develop.
     
  14. Jun 16, 2017
    Glenn

    Glenn Kinda grumpy old man Staff Member Sponsor

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    Generators don't generally charge at idle so I'm a bit confused by your post about a positive reading while idling.
     
  15. Jun 16, 2017
    haighfam

    haighfam Member

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    I ran the rpms up to about 1500 for a couple of minutes and voltage reading at regulator never went above battery voltage.
     
  16. Jun 16, 2017
    PeteL

    PeteL Member Sponsor

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    I'd check carefully for busted wire or bad contact at both generator and regulator, including grounds for both.
    I'd see if the generator brushes are adequate length, and not stuck. You could even polish the commutator.

    Then I'd whack the regulator with a wrench while the engine is running.

    If that doesn't change anything, look into 'flashing' the field coils (polarizing). Or you could start with that - it won't hurt if done correctly.
     
    Last edited: Jun 17, 2017
  17. Jun 17, 2017
    Walt Couch

    Walt Couch sidehill Cordele, Ga. Sponsor

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    If you have a Delco Remy generator that would be the "A" type circuit and to polarize that gen you flash the armature. Rake a short wire across the BAT and ARM terminals of the regulator. If you have a prestolite generator then it will probably be as what PeteL sez.
     
  18. Jun 17, 2017
    PeteL

    PeteL Member Sponsor

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    Thanks for clarifying the difference. I didn't recall which was which.
     
  19. Jun 18, 2017
    haighfam

    haighfam Member

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    I checked all of the connections, cleaded and tightened, replaced one suspect ring terminal. Verifyied I have the Delco Remy generator and flashed the armature. Started the jeep. There is no voltage output from the generator. Where to go from here? Dissaemble the generator and check stator, commutator and brushes?
     
  20. Jun 18, 2017
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member Sponsor

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    Per the manual with the engine running jump the field & battery terminals together at the regulator- if the genny is good the voltage at the armature terminal will jump up to probably 18 volts or more.

    If it doesn't then it's time to take it to the shop.

    If it does jump up follow Pete's advice with the wrench, if that doesn't fix it get a new regulator.

    H.
     

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