Generator over voltage.....

Discussion in 'Talkback' started by jixer, Jul 9, 2015.

  1. jixer

    jixer Junior Member

    I have a spec K Emerald Plus built in March '94: C943138824
    It only has about 600 hours on it and runs like a brand new generator. However, I was curious and how drastic the difference was in the brightness of the lights running off the batteries vs. off the converter. It basically got somewhat intensely brighter. I eventually decided to check the voltage and its in the 140V range! I suspect it has been like this for a long time and seemingly nothing has gone bad yet. I am having trouble finding info on what regulates voltage in these units. Any guidance is appreciated.
    Thanks in advance.
     
  2. C Nash

    C Nash Senior Member

    The lights are burning off the 12 volt battery system. When the converter is charging there are probably about 13.8 volts going to the lights. Not unusual for them to brighten especially if the batteries are getting weak. As far as the 140 volts that seems high to me.
     
  3. jixer

    jixer Junior Member

    Right. but I can't seem to find any info on testing the regulator. I called several repair and RV places and none of them seemed really confident in how to approach it which seemed very odd to me.
     
  4. C Nash

    C Nash Senior Member

    This may help https://www.cumminsonan.com/www/pdf/manuals/965-0528.pdf. I doubt that the regulator can be set. may be a solid set type reg. I would call a Onan dealer for this problem. All I see is that it should be 120 volt output so 140 is high. Where was you checking voltage from? Outlet in RV??
     
  5. C Nash

    C Nash Senior Member

  6. jixer

    jixer Junior Member

    I don't know. Im hoping to dig a little deeper in to this on Sunday, so hopefully I will have more information.
     
  7. jixer

    jixer Junior Member

    And yes.. the testing procedure was in the document. Thank you!
     
  8. jixer

    jixer Junior Member

    OK. tested the RPMs with an oscilloscope and it read dead on 60Hz while idling after warm up. If I change the rpm by manually moving the throttle, the rpms change and so does the frequency and voltage. If I slow it down to match 120V the Hz also drop significantly. Sounds like a bad regulator. Next step is to remove it and test it.
     

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