Voltage regulator upgrade? Keep frying voltage regulators with swap

New Hemi Engine Swaps

  1. Uhcoog1

    Uhcoog1 Well-Known Member

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    I've had three failed voltage regulators since making the Hemi swap. First died when I first completed the swap. Second died 2 months ago when at a HPDE event at Texas world speedway. Third died yesterday when running with lights after a HPDE day.

    I'm guessing either the duralast part isn't very good, or the 160 amp alternator combined with my high electrical draw is causing issues.

    When it fails, the alternator starts charging at full amperage at 18 volts. Yeah, there's 'collateral damage' every time it happens.

    What is the most dependable voltage regulator that could be used with the Hemi 2 field wire alternator? I'd like something from a modern day car with a high amp factory alternator, if possible.

    The voltage regulator I've been using is the factory replacement for my 73 duster.
     
  2. RedFish

    RedFish Well-Known Member

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    In most cases there is a fault somewhere, like a intermittent short to ground that causes this. A friends Chevy pickup is a perfect example but the whole story on it is more than I care to type. Who ever installed the Autozone 350 didn't do a very good job of putting the wiring back in looms and such where it belonged.
    A large red wire that went to the BATT terminal at that distributer cap had a tiny chaffed through spot. When everything under the hood including this wire got hot enough the wire would sag just enough to short to the intake. So he could drive it to work and back daily without a problem. Every time he went into town smoke poured from under the dash.
    I did find about 2 inches of that wires insulation melted/swelled/lumpy but the major damage others were repairing was always at bulkhead and under dash, along with alt' and reg' fried.
    He had this trucked towed a few times to more than 1 shop before he finally had it towed here.
     
  3. toolmanmike

    toolmanmike FABO MODERATOR Staff Member FABO Gold Member

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    Make sure you have a especially good ground for the regulator. A simple screw attachment through the bracket into the firewall may not be enough especially through fresh paint. Mine did the same. I boiled my battery and blew a bunch of light bulbs out at 16+ volts. tmm
     
  4. moparlover

    moparlover Well-Known Member

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    I'm pretty sure that you have a denso alternator... which model is it? the newer Chrysler cars had densos. denso comes in a 160 amp size...

    those are self regulated with a sense wire. they do not use an external voltage regulator....

    http://autoshop101.com/trainmodules/alternator/alt101.html

    basically, one wire goes to the battery (the big one) they have a ground, the sense wire senses the voltage wherever you connect it and the alternator adjusts itself to make the sensed spot have the right voltage. sometimes they have a L wire which is for a charging indicator light. the Ig should get powered when your ignition is on, this enables the alternator.

    [​IMG]

    'S' terminal
    Senses battery voltage
    [SIZE=-1]'IG' terminal
    Ignition switch signal turns regulator ON
    [/SIZE]

    [SIZE=-1]'L' terminal
    Grounds warning lamp
    [/SIZE]

    [SIZE=-1]'B' terminal
    Alternator output terminal
    [/SIZE]

    [SIZE=-1]'F' terminal
    Regulator Full-Field bypass
    [/SIZE]


    http://www.forabodiesonly.com/mopar/showthread.php?t=97736
     
  5. 72BBSwinger

    72BBSwinger Well-Known Member

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    Wrong
    Not all Denso alternators are the same. The ones that bolt to the new Hemis are externally regulated via the ecu.
    Wade try a 80's Dodge pickup regulator. And maybe a Echlin Napa brand?
     
  6. moparlover

    moparlover Well-Known Member

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    the new ones i cant find the pinouts, but it looks like they have a 2 wire pigtail and the main charge wire. it looks like the two wire pigtail is a sense wire and IG wire.

    but i'd suggest this... give these people a call, maybe they can give you info. i've seen the guy post on other forums about different alternator questions, he's a guru.

    http://www.mechman.com/
     
  7. 5.7 hemi

    5.7 hemi FABO Gold Member FABO Gold Member

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    Talk to Dave Weber at modern muscle, he drew me a schematic to use a stock regulator with the hemi alt. and it worked just fine......til I found out I had a problem somewhere else. But it did work just fine and so give him a buzz.
     
  8. teringer

    teringer ase master hall of fame FABO Gold Member

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    you need a heavy duty voltage regulator to handle the extra amps on the alt .when we upgrade the alternators on the emergency vehicles we also change out the regulators. go to a local rebuilder that handles truck fleets/ note these are not cheap. the field wires only carry 2/3 amps on a regular vehicle/ about 6/7 on heavy duty systems its not much of a difference but its 50% higher, in may be cheaper to get a different alt with internal reg.
     
  9. cudaman51

    cudaman51 Well-Known Member

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    I second what teringer said, A higher capacity alternator requires more field current to supply enough magnetic field to generate more power and the small regulator just cant do it
     
  10. mcat

    mcat Well-Known Member

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    post up the schematic please
     
  11. 67Dart273

    67Dart273 FABO Gold Member FABO Gold Member

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    I'm not sure this makes perfect sense. IF he has one with integral regulator, why would it not have the proper regulator already installed?

    Additionally, the Chrysler "big frame" 100+ amp alternators of the late 70's used the same regulator as the small frame 30+ -- 60+ amp units

    Here's what I think:

    1....Something could be mis--wired

    2....The alternator field could have PARTIAL SHORT which does happen and causes excessive field current..........so measure it. Hook a multimeter in series (ammeter / current) and slowly turn the rotor so the brushes "average out"

    3....And there's the everlasting problem of Chineseo quality. Where are you getting regulators? Maybe you should try the junkyard, as in "old stock"

    My beater piece of you-know-what old FJ-40 ran a big frame Mopar alternator for most of it's "life" AKA dual batteries and Warn 8K "wench." The regulator that I put on there in about 1975 or so was a used Mopar, and it was STILL ON THERE when I junked it a few years ago

    [​IMG]
     
  12. Jousi

    Jousi Active Member

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    I had just similar problems, well first was easy, corroted connector in the main supply line to battery.

    But after that, maybe once a week it raised the voltage over 15volts and more. I solved it by making relay to the system, so the switched 12V which is normally coming from bulkhead and supposed to go to the regulator and + field by original wiring, is now just controlling the relay, and 12V is coming directly from battery to regulator and + field.

    No problems since.
     
  13. 72BBSwinger

    72BBSwinger Well-Known Member

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    That is a simple solution. What amperage is your alternator?
     
  14. 67Dart273

    67Dart273 FABO Gold Member FABO Gold Member

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    While what you fixed was a legit problem, it has nothing to do with burning up regulators or heavy field current. What was going on there is that the bad connections in your wiring harness were providing LOW voltage to your regulator, and the IGN terminal is not only power for the regulator, it is also voltage sensing.

    So the regulator "sensed" that voltage was LOW and ramped up charging voltage to compensate. This is why I've got many many posts on checking regulator grounding and harness voltage drop.
     
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    • 5.7 hemi

      5.7 hemi FABO Gold Member FABO Gold Member

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      I no longer have it, sorry.
       
    • Jousi

      Jousi Active Member

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      130 amps.

      For 67Dart273, this was the fix that worked, after all fault finding, extra grounds for regulator and motor to body etc. and all new wires everywhere of course.
      And surely it blowed 2 regulators and one battery boiled. These chinese regulators pop right away when voltage goes too up and then 18V is constant.
      Uhcoog1 problems sounded quite similar like mine was.
       
    • Uhcoog1

      Uhcoog1 Well-Known Member

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      FYI-

      This is how I wired mine:

      http://www.forabodiesonly.com/mopar/showthread.php?p=1969506503#post1969506503


      I have not tried to improve the ground since I've been having issues, though the firewall is sanded down to bare metal about a penny size behind one of the screws (for the voltage regulator to lay flat on).
       
    • Uhcoog1

      Uhcoog1 Well-Known Member

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      FYI - unplugging the voltage regulator didn't help. I had to cut the 12v to the alternator for it to quit charging.

      Also, I just checked resistance between the VR and body, alternator, engine, etc = 0 ohm resistance
      I checked the trunk battery to frame connection point, 0 ohm.
      And then from that point to the opposite frame rail = 0 ohm.
       
    • moparlover

      moparlover Well-Known Member

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      would you mind if i ask the model of your alternator?

      again, as i have stated several times... every mopar alternator i look up from the 2005 year had an internal voltage regulator. 1 battery wire. a two plug connector. the wires are "field control" and "sense"

      field control, when ign + applied causes output to happen. field sense detects voltage and internally adjusts the output voltage on the battery wire to keep from overchargeing.

      on the new cars they have a PCM that basically turns the alt off if the battery temperature gets high. it's not a voltage regulator but it drops the "field control wire" voltage to shut down charging so the battery doesnt overheat. the sense wire also goes to the PCM but really that sense could go anywhere on your car where there is a constant +

      all of the sites and documentation i have checked do not list the newer hemi alternators has having a FLD / FLD as the two wires. the are FC and S

      if you post the model of the alternator maybe we can find exact information
       
    • 72BBSwinger

      72BBSwinger Well-Known Member

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      Make sure the case of the alternator is metal to metal with the front cover. I just took mine to my alternator guy to disassemble and blast so I could powder coat the case and he said to grind it back off where it mates with the front cover. That goes for the front cover too. He also said the regulator my car came with would be totally fine to use with it.
       
    • Uhcoog1

      Uhcoog1 Well-Known Member

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      Thanks for helping.

      Here's a pic of the sticker on the alternator.
      And all the numbers on the sticker:
      04896805aa
      421000-0262
      12v
      46588

      [​IMG]

      I checked the alternator to front case - 0 ohm
      alternator to body - 0 ohm
      alternator to VR = 0 ohm
       
    • Uhcoog1

      Uhcoog1 Well-Known Member

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      When searching the Denso part number, I ran across this site, that says externally regulated:
      http://www.spidermarine.com/showite...% NEW Nippondenso 12 Volt 160 Amp Alternator


      Same thing here:
      Reg Location: external
      [ame="http://www.amazon.com/ALTERNATOR-CHRYSLER-SERIES-MAGNUM-CHARGER/dp/B007COSQCQ"]ALTERNATOR 05-07 CHRYSLER 300 SERIES DODGE MAGNUM 06-07 CHARGER 2.7 3.5 5.7 6.1 : Amazon.com : Automotive[/ame]
       
    • 67Dart273

      67Dart273 FABO Gold Member FABO Gold Member

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      If this is the case, then could he be? causing his own doom?

      That is by incorrect hook-up

      Example on the Delco integral, you must use either a warning lamp as designed, or an isolation diode in the no1 excitation wire or the diode trio will eventually fail.

      Unfortunately I am NOT familiar with these and how to adapt them.

      If you want to know how preposterous the "simple" job of keeping your battery charged has become, read this

      http://www.motor.com/article.asp?article_ID=1606
       
    • Uhcoog1

      Uhcoog1 Well-Known Member

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      Been using the Duralast VR733 voltage regulator. Comes with a 1 year warranty, although when I bought it, it came with a lifetime warranty. So, I get a 'free' one everytime it fails, but it kills something else in the system everytime it does.
       
    • Uhcoog1

      Uhcoog1 Well-Known Member

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      I just did a quick search. 1989 dodge 1 ton diesel has the same PN for the VR.



      A search for a high output voltage regulator yielded this:

      "The Problem
      Since 1987 for Dodge and Chrysler and 1991 for Jeep, vehicles have external regulator alternators that are controlled by the Alternator Voltage Control Module inside the Engine Control Unit, ECU (computer) . ..."
      http://alternatorparts.com/external-voltage-regulator-high-output-alternator-kit.html
       
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