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charging snafu

Discussion in 'Early CJ5 and CJ6 Tech' started by heffleysmill, Jul 6, 2011.

  1. Jul 6, 2011
    heffleysmill

    heffleysmill 7 Slot Hotshot

    Columbus,TX
    Joined:
    Jun 4, 2010
    Messages:
    152
    I have already replaced my 12v anternator on my 57, because it was charging intermittant.
    14v at the alt under load
    3v with the load off
    12.5 volts at the batt
    and scrambling voltages at the amp gauge
    switched the meter to AC and had a steady pulse of 50.2v AC at all points but the battery
    what would have caused this problem?
    Just would like to know for the future
     
    heffleysmill, Jul 6, 2011
    #1
  2. Jul 6, 2011
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    cordele, Ga.
    Joined:
    Mar 29, 2007
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    5,922
    1. 14V under load could be normal depending on battery status and alternator output capacity.
    2. 3v with load off does not compute? Never try to run an alternator without a load.
    3. 12.5 volts at battery is a normal static voltage range.
    4. Don't know what this means. Amp gauge only reads amps not volts.
    5. Trying to read DC volts with the meter on AC doesn't work either and is hard on the meter. That reading means nothing.
    6. Usually a fluctuating alternator output can be caused by internal parts fractured due vibration which causes them to work/not work.
    Also a loose belt will cause the alt output to fluctuate.
     
    Walt Couch, Jul 6, 2011
    #2
  3. Jul 6, 2011
    Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    Tantallon, Nova...
    Joined:
    Nov 22, 2003
    Messages:
    8,124
    Alternators/generators work by turning their outputs full on (high voltage) & full off (zero) really fast, adjusting the ratio between the two states to "average" 14 volts or so. The battery acts as a load to "smooth" the pulses out into stable DC. If you're reading only 12 volts at the battery & seeing the higher voltage pulses (your AC reading) everywhere's else I'd suspect a bad connection between the alternator & battery. Without that battery load on there some alternators can do weird things.

    H.
     
    Howard Eisenhauer, Jul 6, 2011
    #3
  4. Jul 7, 2011
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    cordele, Ga.
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    Concur with all above.. Without a load on the alternator , it can go as high as 120Volt.
     
    Walt Couch, Jul 7, 2011
    #4
  5. Jul 7, 2011
    EricM

    EricM Active Member

    Southern California
    Joined:
    Dec 19, 2007
    Messages:
    1,019
    Running an alternator without a load can also blow the diodes.
     
    EricM, Jul 7, 2011
    #5
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