Stopped Charging?

Electrical and Ignition

  1. coalman

    coalman Well-Known Member

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    Just started the car and was charging like normal 14 volts, then just quit and dropped to 12 volts. Any advice? Thanks
     
  2. 67Dart273

    67Dart273 FABO Gold Member FABO Gold Member

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    Let's start with year, make, model, and does it have stock mopar charging system, and stock mopar wiring?
     
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    • CFD244

      CFD244 FABO Gold Member FABO Gold Member

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      Del will get you diagnosed the right way.
       
    • coalman

      coalman Well-Known Member

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      Mad bypass, two wires to starter relay from alternator, standard alternator and voltage regulator with the relay setup. Thanks
       
    • 67Dart273

      67Dart273 FABO Gold Member FABO Gold Member

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      OK but what year, or if 69/ earlier has it been converted to a 70/ later VR. This stuff is important buddy.

      Does your VR look like this? (69/ earlier)

      IMG_6435.jpg

      Or like this? (70 and later)

      topic=7449.jpg
       
      Last edited: Jun 29, 2021
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      • coalman

        coalman Well-Known Member

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        Sorry for that, 1966, 360 engine with the earlier voltage regulator. Thanks
         
      • 67Dart273

        67Dart273 FABO Gold Member FABO Gold Member

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        OK great. Start by disconnecting green field wire at alternator and "rig" an alligator clip lead to the alternator terminal, and direct over to the battery. Start and run and monitor battery voltage. Voltage should come up but don't allow above 16V or so. If that works, it is in the field wiring or VR

        If voltage stays low, monitor the output stud right at the alternator to make sure there is no break in the charge path to battery. If no change (voltage low, near 12V) you have trouble in the alternator
         
      • coalman

        coalman Well-Known Member

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        Got it, I will try it in the morning. Thanks, for help!
         
      • coalman

        coalman Well-Known Member

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        Just ran it, field wire off at alternator, multimeter reads 12.22 at alternator stud, voltmeter reads -12.00. Thanks
         
      • 67Dart273

        67Dart273 FABO Gold Member FABO Gold Member

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        First thing I'd do is check the brushes they come out in seconds, see if they are worn, gummed up with dirt / grease etc, general condition. You can also check between the field and the case, should have low resistance
         
      • coalman

        coalman Well-Known Member

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        Should I just take it back? Lifetime warranty AutoZone. Thanks for help
         
      • 67Dart273

        67Dart273 FABO Gold Member FABO Gold Member

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        YEH!!
         
      • coalman

        coalman Well-Known Member

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        Alternator didn't fix it. Thanks
         
      • 67Dart273

        67Dart273 FABO Gold Member FABO Gold Member

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        Well you may have multiple problems. Repeat the full field test that is bypass the VR and see if it charges AND it just might be that the "new" alternator is defective. "It happens"
         
      • coalman

        coalman Well-Known Member

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        Same thing as the original one. Can you run a check from the output terminal through a multimeter in the D/C volts setting? Thanks
         
        Last edited: Jul 4, 2021
      • 67Dart273

        67Dart273 FABO Gold Member FABO Gold Member

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        Ok let's start all over..........from the beginning. Obviously we are missing something here

        1...Very first thing is to make certain that the field is grounded on one terminal, and that the other one is not SHORTED to ground. It is "too common" for rebuilds / replacements to have such things as missing hardware in the brush holders.

        If you need to remove the alternator and if you still have the old one, test both Take your ohmeter and do a "short" test so you know what it reads at a short. Most meters do not read zero, they read some "tenths" due to innacuracy and due to probe / lead resistance.

        Now investigate the alternator one brush should be grounded. Stabe one meter probe firmly into the case, and the other on the insulated probe. You should read fairly low resistance but NOT a short

        2...Next "Full field" the thing and see if it charges and make SURE that the field is drawing current If you can, measure field current with your meter. "Rig" a wire from the battery (or large stud on starter relay) to the field, with the meter in SERIES. If the probes are long enough, you can just use them. BE CAREFUL!!! not to ground the meter, because a current/ ammeter goes in SERIES. "End up" with one probe on the battery positive, the other on the INSULATED alternator field. Measure current draw. Should be more than a couple amps, and perhaps less than 6. This varies over the years and with alternator amperage output

        3...If the above is good so far, Hook everything up "normal" EXCEPT the green VR wire. Connect/ disconnect your field jumper---from battery to field--and in subdued light you should see a small spark, and maybe even hear it. SMALL. Double check your ammeter to be certain it is drawing current.

        Now start the engine run at high idle, and monitor battery voltage. See if voltage increases. IF NOT move meter to alternator output stud and see what that reads

        If still low, below 13, ----not charging

        If quite high, VERY high up around 20, AND if voltage at battery is low, YOU HAVE an open/ bad connection in the charge path to the battery
         
        Last edited: Jul 4, 2021
      • coalman

        coalman Well-Known Member

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        Thanks for all your information, the old one was exchanged, I just hope something in the rest of the charging system is knocking the alternators out. Again thanks for all your help, especially on a Holiday...
         
        Last edited: Jul 5, 2021
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