Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Small Genset Project - Feedback Request

  1. Jun 30, 2012 #1
    Hello everyone!

    I want to do a small project, and would like your thoughts:
    I'm going to build a small genset, with a target power output of 3kW, and "one person carry" possibility.

    Using liquid fuel, probably gasoline.
    Although if diesel is a possibility, that would be interesting to study.

    Any thoughts on what engine can be used?
    I thought a small engine, like the ones Honda uses in their small power plants.
    Honda's small gensets go up to 2kW, and are still "one person carry".

    Ideas on what engine to use for this?
    Thank you!
  2. jcsd
  3. Jul 1, 2012 #2


    User Avatar
    Gold Member

    For such a small unit, a single cylinder gasoline engine is probably the simplest.
    A two cycle motor would be cheapest, but I think emission rules have curtailed their availability, so a 4 cycle motor will probably be the best bet.
    A diesel would be substantially heavier, the 20:1 compression mandates hefty cylinder walls.
  4. Jul 2, 2012 #3


    User Avatar
    Gold Member

    If I wanted to build a small, lightweight generator I would use the example of Honda and copy their product. I am humble enough to admit that Honda has invested millions of $ and thousands of engineers over many years to create their product, and that I am only one person with limited experience/education. Why would I sit in a vacuum and ignore all the advances they have achieved?

    Of course, there is always room for improvements in efficiency. I suggest you look for ways to improve existing "top of the line" gensets.
  5. Jul 2, 2012 #4
    Without knowing your constraints (i.e., cost, time, fabrication capabilities), it's hard know exactly what might be helpful. If it was my own project, I'd probably begin by going to a motorcycle dismantler (junk yard) and check the prices of available engines. It won't do any good to have a 3kw generator if you can't afford a big enough engine to spin it.
  6. Jul 2, 2012 #5
    You should decide what you want to use it for first....what voltage do you want....or are your trying to charge 12 volt batteries, for example?

    3kw PORTBLE from miscellaneous components may not be so easy.....HONDA has carefully matched components.

    1 hp is about 3/4 KW...so you'll need about 4 of those units to generate 3 kw....a four HP engine or a bit larger....I think a typical 22" lawn mower engine is about that size...check to be sure....so you could probably get a used four cycle engine cheap from a lawnmower shop.

    And if you are charging 12 volt batteries, maybe a used alternator from an automobile. You should also consiuder the rated engine RPM.....if you want longer life, a engine rated at 1800 RPM will likely do better than one run at 3,600 RPM. You'll to generate about 14 volts for actual charge.

    If you are trying to generate alternating current, for household, that's 60 hertz in the US and 50 hertz in Europe, so you'll have to control the engine RPM to get the output frequency you want.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook