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Thread: Solid State Three Post Relays

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  1. #1

    Default Solid State Three Post Relays

    On the solid state three post relays that are available (V-Twin and Gene Harper both make them???)
    Does the generator light switch off abruptly like on a mechanical relay or does it just slowly fade? Are Gene's or V-Twins the same in function?

  2. #2
    Join Date
    May 2010
    Minot, ME


    find an old nos one those electronic relays are not the most reliable fail in a short time made in china the ones with points are more reliable would rather have an old one than new one dont know about the harper one but do know about the v twin one paul bergeron minot maine 7989

  3. #3
    Join Date
    Dec 2003
    NE IL


    Hey Mark,

    Over the years I've bought 3 solid state relays for 3 different bikes from The Old Dude. I don't know where he gets them, but I have never had a problem with them. The light goes off quickly when it starts, and I have no charging problems. The one I currently have on my '55 pan, I bought and installed in 2004, and in 9 years there have been no problems.
    Bruce Keith
    AMCA #1467

  4. #4
    Join Date
    Apr 2011


    I’ve got a 47 Knuckle that’s been converted to 12v and has a solid state regulator on the butt end of the gen. It has an eagle head on it and says “Electric’s ?????rk’s” I can’t read the second word. In any case is has Red, Green and Black wires coming out of it. Does anyone know how to hook up these wires so that the Gen idiot light goes out and the battery gets charged? Thanks311BCF7F-446C-4AA3-B185-27924FEFE321.jpg

  5. #5
    Join Date
    Nov 2009



    You may be mixing metaphors here...

    A "solid state relay" as you call it would be simply a large diode in place of the mechanical cutout. In addition, there is a smaller diode that controls the idiot light. This would be a direct replacement for the mechanical cutout and keeps the generator in it's original 3 brush configuration. I've seen these fail on occasion, but usually because something gets shorted by accident, generator output is set way too high, too many lights, bad ground etc. Electronics do not like shorts, no matter how fast it may be. These are available from Vtwin and other sources, these are made by V-Tronics:

    You may have been referring to the electronic 3 post voltage regulator that I USED TO make. These are also available from V-tronics: and in my opinion are superior to what I used to make, and cheaper! They both work the same way in essence by varying the generator field voltage in order to regulate generator current output to match the load and at the same time limit maximum voltage output to save your battery. Both use a large diode in place of the cutout and also a small diode controlling the idiot light circuit. Both also require converting the generator to a 2 brush configuration.

    To answer your original question: It depends on how fast the generator speed is increasing. If you very slowly increase speed from a slow idle, the idiot light will slowly fade out, as generator output voltage increases to match battery voltage . On the other hand, revving the motor up fast, the light will appear to switch off very quickly. Doing the same with a good mechanical cutout can get the same result.


  6. #6
    Join Date
    Dec 2001


    Me and my friend have used these for sometime now with no issues. Light goes right out. They come in 6 or 12 volt. We have used the 12 volt ones for our 12 volt conversions. V-twin was the source. I keep a spare on board just in case. I have never had to use it. We also use Cycle Electric 65A generators without the end cap regulator so we can put the 32E cap on them. Looks like you have a 6 volt system on board.

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