Alternator is overcharging and burning up the output wire

Electrical & Ignition

  1. rstockbridge

    rstockbridge Member

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    1. I just installed an MSD Atomic EFI system on my 70 RR. Everything seemed to be going smooth until we took it for a spin and started smelling burnt wires. We figured out that the alternator was putting out too many volts and causing the wire to heat up.

      Any idea what the issue is?
     
  2. 727

    727 Well-Known Member

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    Bad voltage regulator
     
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    • rstockbridge

      rstockbridge Member

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      Just changed the voltage regulator and I'm still having the same issue
       
    • lewtot184

      lewtot184 Well-Known Member

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      regulator isn't grounded good.
       
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      • Traintech55

        Traintech55 Active Member

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        Some questions to ask first,
        1. Is your alternator output rising with the engine R.P.M's.?
        2. Does your R.R. still have the factory voltage regulator?
        Need these answered so I can steer you in the right direction.
         
      • mmissile

        mmissile Well-Known Member

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        Could be almost anywhere. I'd start with the grounds. I ended-up replacing the entire dash harness, rewiring the ignition wiring that burned, checking alternator output, new regulator, a couple gauges, and the ignition-switch....before everything worked correctly in my road runner. I sold it immediately after everything worked on the car.
         
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        • 65-440

          65-440 Well-Known Member

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          My overcharge was caused by a poor connection in the regulator connector. One of those barrel terminals was loose. Replaced the entire connector, all is good now ...

          Had a buddy sitting in the car watching the volt gauge while I put my hands on things under the hood, as soon as I got to the regulator connector the voltage dropped back to 14V ....
           
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          • Traintech55

            Traintech55 Active Member

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            That is why I asked him the questions I did in # 5. If the connector for the ignition feed break's at the regulator, the regulator will ground and the alternator will charge wide open.
             
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            • Nacho-RT74

              Nacho-RT74 Well-Known Member

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              Voltage doesn't melt wires. Amperes does.

              One prove for this, my stereo system works with same AC wire down 120 volts than 240 volts ( of course with the right switch selection )

              However Amperes are sucked in by devices, not pushed in by the alternator
               
              Last edited: Nov 30, 2017
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              • Ranger16

                Ranger16 Well-Known Member

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                I know less about electricity than I do about anything else, but doesn't resistance cause heat and wouldn't a bad ground (or a partially broken wire) cause an increase in resistance?

                That said, would the above condition ALSO result in an overcharge? My little knowledge and gut tell me yes. Someone correct me if I'm wrong.
                 
              • Nacho-RT74

                Nacho-RT74 Well-Known Member

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                the only ways to get melting around are:

                -Short ( at wiring, plug or device itself inside )

                or

                -Path/terminals unable to hold the load ( due dirt/rust or undersized ) sucked by the devices
                 
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                • Nacho-RT74

                  Nacho-RT74 Well-Known Member

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                  also must say high voltage IS ABLE to burn/broke devices ( such as bulbs )... but not melt wires or terminals by itself. A burnt plug due voltage is more a consecuence of a device blown by voltage raise, but not due the voltage itself
                   
                • rstockbridge

                  rstockbridge Member

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                  I ran the wire strait to the battery and that seemed to fix the issue. Thanks for all the responses.
                   
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