Problem with small generator - need help





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  1. #1
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    Default Problem with small generator - need help

    During the load shedding spell some ten years ago I bought a 650 watt Honda generator and installed a lead with a plug in the room where we mostly need electricity at night.
    Everything went well, until the genny started "over generating". It would push more than 300 volts out, and blow everything one would connect to it.

    I then got an inverter unit that switches on within a millisecond from when the power fails. That has worked well, but that setup chows batteries. Including the set when new, I now need to get the 3rd set. 2 x 100 amp deep cycles is not what I want to keep on buying.

    My question is, can one not get a voltage regulator that will ensure the genny does not push more than 220 or 230 volts to the plug? Surely if such a device is part of a car's alternator to keep the voltage below say 14, there must be something similar for a 220 AC system?

    Please advise.
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  2. #2
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    Default Re: Problem with small generator - need help

    Yes you get AVR about up to 10kVA. Google PhD powerhouse as well as www.pss.co.za. They work great if the input is close to pure sine wave. Modified sine input will cause it to constantly adjust and it will under and overshoot while trying to maintain 230V.

  3. #3
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    Default Re: Problem with small generator - need help

    Another thought.

    When the batteries starts getting below say 30% DOD, connect the generator to the inverters input, that it helps to re-charge the batteries, as batteries tend to draw a lot of amps consistently, slowly reducing.

    At 30% DOD it should be in bulk charge state. If not, go lower to 40% DOD if need be. You want to get to bulk charge level.

    The only caveat is that the inverter can take fluctuating power from the generator and smooth it out on it's output. The batteries should help a lot to lessens the fluctuation.

    Note: It is an idea, check it with experts. :-)
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    Default Re: Problem with small generator - need help

    surely the generator can be repaired - depending on the type of alternator over-voltage is either a result of too high engine revs or the alternators AVR is faulty.

    individually measure the inverter batteries, most likely one is at 15 or more volts the other at 10 or less; ie. one is being over-charged the other under-charged.

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    Default Re: Problem with small generator - need help

    Get the generator repaired, sounds like the regulator has gone. On our work generator there is an idle lever that is adjusted to Rev at 230v. Unfortunately we blew a few drilling machines because a clever dick thought that by increasing the idle revs, he can drill through our wooden elect poles quicker.
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  6. #6
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    Default Re: Problem with small generator - need help

    I ran the inverter set-up separately from the genny. I do not want to use it to smooth out the genny output. I merely mentioned it to point out why I prefer the genny.

    I know the output voltage relies on a constant engine speed. This is where the problem lies. The thing goes faster by itself, hence the high voltage. I am looking for a regulator of some sorts.

    I took the genny to the Honda agents, and they could not help me, except for wanting to replace a spring, which did not fix the problem. It appears as if they can only fix by replacing parts, not by fault finding.
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    Default Re: Problem with small generator - need help

    A governor can be very tricky if you don't know how to adjust it. There is a procedure you need to follow, otherwise it will not work right.
    If adjustment doesn't fix it ,then the governor it self could be faulty. I replaced one two weeks ago that had a broken tooth on the plastic gear.
    I also set the output voltage according to the Hertz(cycles). If adjusted properly the output voltage will be on 50Hz under load.
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    Default Re: Problem with small generator - need help

    It might be cheaper (in the longer run) to invest in a bit of a bigger generator - I see these at takealot https://www.takealot.com/ryobi-gener...w/PLID34187771

    Edt - even cheaper at builders https://www.builders.co.za/Promotion...00000000281046
    Last edited by WAJ; 2020/02/13 at 09:41 AM.
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    Default Re: Problem with small generator - need help

    Quote Originally Posted by Poen View Post
    I am looking for a regulator of some sorts.
    That is what the inverter with batteries will be. But I hear you.

    What I have read about generators, listenend to others discussing it over years, I reduced it to two points:
    1) the quality of the AVR is one major thing,
    2) the size of the flywheel a 2nd big thing.

    As loads come on and off, and there can be big changes happening frequently, they are mitigated by 1 and 2 above.
    Load comes on, revs must drop as little as possible.
    Load goes off, revs must stay as constant as it can.

    Then you also have the amount of energy contained in a liter of petrol. Under a good solid load, you get the most bang for your liter of fuel.

    If I had to get a generator, I would use it to recharge batteries. Switch on when SOC is at X, off when SOC is at Y.
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    Default Re: Problem with small generator - need help

    Being in the windy city - perhaps investigate a small wind generator to charge batteries, and the good thing is they can work day and night time.

    Here where I live in Pretroria the wind is useless otherwise I would have gotten one.
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  11. #11
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    Default Re: Problem with small generator - need help

    I am looking for a regulator of some sorts.

    That is what the inverter with batteries will be. But I hear you.

    according to the OP the generator pushes out over 300V, this will kill his ups, no.

    assume the generator is the EM650, if so attached is its manual - pg 7 for wiring diagram, pg 36 for some detail of its governor, pg 6 for causes of abnormal engine speed

    http://www.fujiyachts.net/manuals/Ho...p%20Manual.pdf

    I took the genny to the Honda agents, and they could not help me, except for wanting to replace a spring, which did not fix the problem. It appears as if they can only fix by replacing parts, not by fault finding.

    try a different agent.

    at 10yrs old its quite possible the cost of repairs (if at a honda agent) would exceed the value of the generator. though it could also just need a simple adjustment / loose butterfly / leaking butterfly spindle, etc, etc.
    Last edited by RussellF; 2020/02/13 at 11:10 AM. Reason: added pg 6

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  13. #12
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    Default Re: Problem with small generator - need help

    If you are charging batteries with the generator be careful as a lot of them do not regulate when the battery is near full charge.

    Just monitor your batteries frequently if you do this - prevent overcharging.

  14. #13
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    Default Re: Problem with small generator - need help

    Quote Originally Posted by RussellF View Post
    According to the OP the generator pushes out over 300V, this will kill his ups, no.
    Assuming the gennie is 100% operational, on cheap gennies, that can happen when large loads go off/come on, as the engine cannot slow fast enough. Assuming the gennie is 100% operational.

    A UPS / or inverter can take bigger voltage variations at their input and "clean it" before output, because good UPS'es have a lot of smart features to protect themselves and the loads on their output.

    The amps needed to charge a battery bank that is down to say 40-50% DOD, takes a lot of power at a constant amps, slowly reducing to Absorption phase and then float.
    Bulk is where the raw power is needed, highest amps, most constant load on the engine.
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    Default Re: Problem with small generator - need help

    Quote Originally Posted by WAJ View Post
    It might be cheaper (in the longer run) to invest in a bit of a bigger generator - I see these at takealot https://www.takealot.com/ryobi-gener...w/PLID34187771

    Edt - even cheaper at builders https://www.builders.co.za/Promotion...00000000281046
    I would have considered replacing it, but it has worked less than 20 hours since new.

    I will not consider a two stroke unit because I detest the two stroke fumes. I specifically bought this little Honda because it is four stroke, and I do not need more watts than what it can supply.

    Who should I take it to for setting the governor?

    O yes, and thanks all you guys for all the advice and feedback. Much apprecieted. Collective experience is a powerful tool.
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    Default Re: Problem with small generator - need help

    Quote Originally Posted by Poen View Post

    Who should I take it to for setting the governor?
    I would try a workshop that repairs power tools which include petrol hedge trimmers etc. This is normally a spring and wind pressure unit operated from the speed of the engine. Some have weights to operate the throttle. Perhaps not easy to get to but those that have stripped the unit to get to it will be in the know.

  17. #16
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    Default Re: Problem with small generator - need help

    Something you can check as well is the governor shaft for stickiness to which the governor arm is bolted.

    I had a similar problem on my 6.5kVA genny, where voltage regulation was non-existent after standing for a while. Spraying the shaft with Q20 and moving the arm back and forth for a minute solved the problem.


  18. #17
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    Default Re: Problem with small generator - need help

    The revs do not determine the voltage but the frequency. At 3000 it will be 50hz.

  19. #18
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    Default Re: Problem with small generator - need help

    Quote Originally Posted by desdrake View Post
    The revs do not determine the voltage but the frequency. At 3000 it will be 50hz.
    On my 6.5kVA it definitely did, as well on my 32kVA, which I powered with one of my tractors. At first I adjusted the engine revs to get the required voltage, but added a frequency meter later on for a more accurate setting at 50Hz. Installing an AVR helped a lot with the voltage. The AVR on the (chinese) 6.5kVA is obviously not up to scratch. My UPSes hated it


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