Severe overcharging from my 72

Electrical and Ignition

  1. satchall

    satchall Active Member

    Messages:
    42
    Likes Received:
    1
    Joined:
    Apr 11, 2017
    Location:
    Montgomery
    Local Time:
    5:34 AM
    my 72 is currently charging at 16-18 volts and i have no clue why. Replaced ballast resistor, voltage regulator, and trace wiring to ensure it was not too brittle. Any thoughts?
     
  2. Oaktree

    Oaktree Long time Mopar guy

    Messages:
    194
    Likes Received:
    48
    Joined:
    Aug 28, 2014
    Location:
    N.H.
    Local Time:
    6:34 AM
    Sounds like either the VR is bad (or has a bad ground) or the wire from the field to the VR is shorted to ground somewhere.

    The ballast resistor is part of the ignition and has nothing to do with the charging system.
     
    • Agree Agree x 3
    • jimjimjimmy

      jimjimjimmy lobsterman FABO Gold Member

      Messages:
      4,169
      Likes Received:
      914
      Joined:
      Nov 2, 2010
      Location:
      p. e. i.
      Local Time:
      7:34 AM
      check and clean your bulkhead connector if there is a poor connection there it will cause an overcharge problem and it may start melting down if not cleaned .
       
      • Agree Agree x 1
      • kiss

        kiss Well-Known Member

        Messages:
        850
        Likes Received:
        391
        Joined:
        Sep 1, 2008
        Location:
        San Diego, CA
        Local Time:
        3:34 AM
        Here's what i'd do in this order:

        Check the battery to engine block negative cable, make sure both ends are clean and tight

        The voltage regular ground from the factory was crappy at best. Run a ground wire from battery- to the voltage regulator body. Scuff up the body at a mounting bolt and mount it there, or add a little screw to the side of the regulator body and add the negative wire there.

        Check the FLD wires at the alternator and make sure they're clean/tight, and trace them through the wiring harness if needed to check for any breaks/damage.

        Check the bulkhead connector as well as the connection quality at the ammeter gauge behind the cluster.

        Lastly, it could be a problem with the battery. Take the battery off, charge it to full, and reinstall it. If the same symptom occurs try another battery if you have a spare. It could also be a faulty alternator. I'd check all of the above first.
         
        • Like Like x 1
        • satchall

          satchall Active Member

          Messages:
          42
          Likes Received:
          1
          Joined:
          Apr 11, 2017
          Location:
          Montgomery
          Local Time:
          5:34 AM
          My only thought about the alternator is that if it were the problem wouldn’t it be stopped from cranking out too much power by the voltage regulator?
           
        • Tooljunkie

          Tooljunkie King of cobble/master of the broken bolt FABO Gold Member

          Messages:
          8,639
          Likes Received:
          7156
          Joined:
          Jul 22, 2017
          Location:
          Manitoba
          Local Time:
          5:34 AM
          Not the sort of thing an alternator does. Unless its been apart and a brush insulator is broken or left out.
          Battery plus in on one terminal, ground on the other. Now its not a 100%ground,it’s regulated. 100%ground is called “full fielded”.
           
        • satchall

          satchall Active Member

          Messages:
          42
          Likes Received:
          1
          Joined:
          Apr 11, 2017
          Location:
          Montgomery
          Local Time:
          5:34 AM
          So probably not the alternator?
           
        • Killer6

          Killer6 Well-Known Member

          Messages:
          2,254
          Likes Received:
          679
          Joined:
          Mar 9, 2015
          Location:
          PA
          Local Time:
          5:34 AM
          Probably not, it can in rare cases where a rotor winding shorts to the rotor body near the field end connection slip-ring. But it's 99.99% not likely.
          Most common cause is a poor connection from the power to ign. feed all the way through to the wires to the ballast/regulator/alternator B+(usually Dk. Blue). Any and
          all connections including bulkheads at the firewall, column connector, ign. sw. itself, splices, etc. If any of these is poor, the regulator sees less V than the battery, so it
          thinks it hasn't charged enough yet. The blue wire at the reg. may be seeing 14.3V while the Batt. may be seeing 16.2V. The regulator satisfies itself, w/o an accurate
          reference voltage it doesn't know & doesn't care what voltage is actually at the battery.

          EDIT: I am going on the assumption that You have a std. '72 squareback alt. and
          2 wire electronic regulator..........................
           
        • satchall

          satchall Active Member

          Messages:
          42
          Likes Received:
          1
          Joined:
          Apr 11, 2017
          Location:
          Montgomery
          Local Time:
          5:34 AM
          Correct with the regulator and alternator. So where should i start to check the bulkhead connection?
           
        • Killer6

          Killer6 Well-Known Member

          Messages:
          2,254
          Likes Received:
          679
          Joined:
          Mar 9, 2015
          Location:
          PA
          Local Time:
          5:34 AM
          This issue has been addressed a number of times before, so You're not alone. 67Dart273 has posted the wiring diagrams a number of times, get that first, then check
          the voltage working Your way from the feed through the bulkhead at the connections in & out of the ign etc. looking for a drop. Back out through the bulkhead and on.
          Sometimes I have to use a headlamp with leads and a probe, it should lite bright the whole way from one end of the system to the other, it's a good "load fail" indicator.
          It's easy to light a tiny test lamp/led, and to that end You would really go right to the regulator first and check the blue wire key in "run", bright headlamp and good V
          (within .4 of V at the Batt) then the problem lies elsewhere. If You've got points, unplug the dizzy so 'Ya don't burn 'em up while testing.....................................
           
        • RedFish

          RedFish Well-Known Member

          Messages:
          23,061
          Likes Received:
          2008
          Joined:
          Sep 5, 2007
          Local Time:
          5:34 AM
          Have you considered bad battery?
           
        • satchall

          satchall Active Member

          Messages:
          42
          Likes Received:
          1
          Joined:
          Apr 11, 2017
          Location:
          Montgomery
          Local Time:
          5:34 AM
          So the voltage generally (13.6) begins in the normal range and sort of creeps up. Recently it started at 18 volts. It changes relative to rpm as well.
           
        • satchall

          satchall Active Member

          Messages:
          42
          Likes Received:
          1
          Joined:
          Apr 11, 2017
          Location:
          Montgomery
          Local Time:
          5:34 AM
          So the voltage spikes when the regulator IS grounded. When it isn’t the voltage is low (maybe that cuts off the charging from the alternator).
           
        • satchall

          satchall Active Member

          Messages:
          42
          Likes Received:
          1
          Joined:
          Apr 11, 2017
          Location:
          Montgomery
          Local Time:
          5:34 AM
          The regulator (blue wire) is seeing 11 volts while the battery is at 12.2
           
        • barbee6043

          barbee6043 barbee 6043 FABO Gold Member

          Messages:
          10,148
          Likes Received:
          2897
          Joined:
          Jul 20, 2008
          Location:
          Shepherd, Texas ( SE Tx)
          Local Time:
          5:34 AM
          I had similar problem last year, checked all kinds of stuff as recommended, replaced the alt. and problem disappeared.
           
        • Killer6

          Killer6 Well-Known Member

          Messages:
          2,254
          Likes Received:
          679
          Joined:
          Mar 9, 2015
          Location:
          PA
          Local Time:
          5:34 AM
          Yes, as suggested above, the regulator needs to be grounded......but a poor ground results in what you've just observed. So a poor ground will result in poor charging,
          not over-charging. The reg is grounding the green field wire coming from the alt to generate the field in the rotor windings, controlling the duty cycle to maintain the set
          voltage. If You're losing 1.2 volts, that could get You to 16V, and since that blue wire is powering the field, the more the reg grounds the rotor the more current it uses
          helping to drop the local voltage there.
           
        • satchall

          satchall Active Member

          Messages:
          42
          Likes Received:
          1
          Joined:
          Apr 11, 2017
          Location:
          Montgomery
          Local Time:
          5:34 AM
          Any ideas on a way to get my voltage level? I was told bypassing the ammeter might correct it.
           
        • Killer6

          Killer6 Well-Known Member

          Messages:
          2,254
          Likes Received:
          679
          Joined:
          Mar 9, 2015
          Location:
          PA
          Local Time:
          5:34 AM
          Bypassing sending all the charging current through the firewall twice and the ammeter is always a plus, there have been a few ways it has been executed, but none are
          going to fix this problem. You need to check all the engine and body grounds, then do what I suggested in post #10. If You have a voltage drop, You have to find & fix
          the culprit.
           
        • satchall

          satchall Active Member

          Messages:
          42
          Likes Received:
          1
          Joined:
          Apr 11, 2017
          Location:
          Montgomery
          Local Time:
          5:34 AM
          I checked the voltage at the bulkhead and the regulator but i'm not sure where to test from there. The voltage loss has to be before both of those point because they're both low
           
        • oldkimmer

          oldkimmer FABO Gold Member FABO Gold Member

          Messages:
          10,473
          Likes Received:
          1303
          Joined:
          Nov 11, 2006
          Location:
          Kindersley, Saskatchewan,
          Local Time:
          5:34 AM
          I have found the regulator plug to be the culprit Kim
           
        1. This site uses cookies to help personalize content, tailor your experience and to keep you logged in if you register.
          By continuing to use this site, you are consenting to our use of cookies.