Charging voltage too high.

Discussion in 'Electrical and Ignition' started by LivewireBlanco, Jul 3, 2018.

  1. LivewireBlanco

    LivewireBlanco Well-Known Member

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    After getting the new 318 tuned up I checked the battery voltage while running and it was between 15 and 16 volts. Just to rule it out I tried a new voltage regulator and it didn't change. What should I look for? Car is a 1971 Dart Swinger.
     
  2. mopar_nocar

    mopar_nocar Well-Known Member

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    Dirty/corroded connections at the bulkhead, alternator, battery and amp gauge.

    And a good ground at the voltage regulator.

    Glad you got it started.

    sb
     
    Last edited: Jul 3, 2018
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    • TrailBeast

      TrailBeast Slightly Twisted Member

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      Just so you know, when the regulator see's low voltage at it's blue wire it compensates for that by overcharging.
      The blue wire ties into the harness at what they call a "welded splice" to sense the system voltage, so if there is a crappy connection there it can cause what is happening.
      This is why some of us remove that blue wire from the welded splice and route it direct to the battery + at the solenoid using a relay.
      This also can sometimes solve the jumpy amp meter needle that some have.
       
    • LivewireBlanco

      LivewireBlanco Well-Known Member

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      Got a good ground on the voltage regulator. The wired at the alternator are not the best...
       
    • LivewireBlanco

      LivewireBlanco Well-Known Member

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      Ammeter is solid, I bet this blue wire is not that great. The green isn't all that good looking either... hell all the wires aren't great! What gauge are the green and blue wires?
       
    • barracudadave67

      barracudadave67 FABO Gold Member FABO Gold Member

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      Your factory wireing schematic will have the gages of all wires listed.
      Dave
       
    • 67Dart273

      67Dart273 Well-Known Member

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      The way I test for this is as follows:

      Rig a meter probe as close as you can get to the blue VR power (IGN) terminal. Don't unhook anything because you want the load (current draw) to be "as run." One place is to probe the "key" side of the ballast, the other is the blue alternator field

      Hook your remaining probe to battery + and turn the key to "run" with engine stopped. You are hoping for a very low reading, the lower the better, and less than a few tenths of a volt

      If your read more than .3--.4V (3/10 of one volt) that drop will be ADDED to the VR set point when running

      EG let's say you read 1.4V. You run the car and if the VR is charging nominally 14V, the battery will read 15.4V

      ==========================

      As Greg said above, "one way" out of this is to clip the blue ignition feed wire coming out of the bulkhead. Use the end at the bulkhead to trigger a relay, and get a breaker or fuse and feed the relay contacts off the starter relay stud. Now connect your other end of your clipped blue wire (IGN run or IGN1) to the load contact on the relay

      ===========================

      You also want to check the GROUND end of this. Do this test first with all loads off, and again with headlights, heater, running

      Run the engine, set RPM to simulate low to medium cruise RPM. Stab one probe into the battery NEG post, and the other into the VR mounting flange. Be sure to stab through rust, paint, etc

      As in the first test, you are hoping for a very low reading, zero is perfect

      IT DOES NOT HURT to improve the battery (block) to body ground. What I do on a V8 is bolt a short starter cable to the rear of the driver side head. Look at your pass side head front, the same bolt holes are on the driver side rear. Bolt the other end to a good through bolt in the firewall, or to one of the master cylinder studs.
       
    • LivewireBlanco

      LivewireBlanco Well-Known Member

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      Thanks guys! I'll be checking thingsout and reporting back soon! Y'all have a great 4th tomorrow!
       
    • toolmanmike

      toolmanmike FABO Staff Staff Member FABO Gold Member

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      Agreed!
       
    • LivewireBlanco

      LivewireBlanco Well-Known Member

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      Keyside of ballast in run from battery + terminal is 1.6v. I'm still having that voltage drop issue.
       
    • 67Dart273

      67Dart273 Well-Known Member

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      That's a "bunch." About what I had on my 67. One way around this is to insert a relay to feed the ignition/ under hood "run" loads
       
    • LivewireBlanco

      LivewireBlanco Well-Known Member

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      Ok, I'm going to look into this. Hopefully I can find more info. I'll be googling relay just so you know... This is all new to me.
       
    • 67Dart273

      67Dart273 Well-Known Member

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      Biggest problem is figuring out where to mount it. You want it "dry" as you can, and away from engine heat, some. Basically, electrically you do this:

      Locate the "ignition run" (IGN1) traditionally dark blue coming out of the bulkhead connector. "At some point" it will disappear into the engine harness, you can unwrap it. You cut it at some point

      Basic wiring for a "Bosch" relay:

      newest-tyco-relay-wiring-diagram-968.jpg

      The above is a basic diagram. 30 is main power for the loads goin into the relay. So feed that from the starter relay stud through a big fuse or breaker like 20A

      87, showing headlights here, goes to the cut end of your ignition "run" wire on the engine harness side

      85 you ground and you can run this through a small toggle for a little bit of "anti theft."

      86 you hook to the cut end of the "run" wire which comes out of the bulkhead connector.

      You can buy relay sockets with a mounting hole and wire pigtail

      71XXkrFOISL._SX425_.jpg
       
    • LivewireBlanco

      LivewireBlanco Well-Known Member

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      You're the man! Now this I can understand! What size fuse should I use or would you advise a breaker?
       
    • 67Dart273

      67Dart273 Well-Known Member

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      Well the underhood loads don't draw that much, so maybe a 20A fuse max or maybe a 15A breaker max The size of that wire varies over the years, and you don't want so small a device that it nuisance blows/ trips and leaves you out there on the freeway with no power!!
       
    • BillGrissom

      BillGrissom Well-Known Member

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      Just to make clear, the Vreg regulates the voltage difference it sees between its case and its +12 V supply wire (usually blue). Ideally, those are the same voltages as BAT- and BAT+ terminals, resp. You need to insure that is true by eliminating extraneous resistances. The factory thought a sheet-metal screw into the body was a sufficient electrical connection, and that probably worked to get thru the 3 yr warranty, but usually not true 40 yrs later.
       
    • LivewireBlanco

      LivewireBlanco Well-Known Member

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      I get it. I'm going to run a relay when I get a chance. I have a leaky fuel sending unit and brake drag to fix first.
       
    • 67Dart273

      67Dart273 Well-Known Member

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      THREE year??? Boy did I get screwed!!!
       
    • MileHighDart

      MileHighDart FABO Gold Member FABO Gold Member

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      I did as 67Dart273 suggested on my '68 and it fixed my overcharging, and my flickering headlights too.
       
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      • LivewireBlanco

        LivewireBlanco Well-Known Member

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        Ok, I put in the relay and wired it as shown and now I'm getting no charge. I previously ran a 10 gauge wire from alternator to starter switch battery lug. Is this messing up my charge voltage from alternator?
         
      • LivewireBlanco

        LivewireBlanco Well-Known Member

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        Found a field coil wire broken. Fixed the charging issue.

        Quick question, for a voltmeter could I run the power wire to one of the relay wires? 87 or 86?
         
      • 67Dart273

        67Dart273 Well-Known Member

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        I would pull your voltmeter off 87. That is "as close as you can get" to the battery, which is what you are trying to monitor
         
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