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aguablanco's avatar
aguablanco
Explorer
Sep 12, 2015

Generator Sizing

I have been looking for a generator for our TT for a while now and I have a question I hope I can get some answers to. My trailer will most likely need around 3.5k watts to run everything including AC. My question is, if I buy say 4k watts and run everything at once, the generator will run at full RPM to make that happen. 3600 RPM would be fairly noisy as I am not going to buy the Honda's etc. So, if I were to buy say a 6000-7000 watt generator wouldn't that then run at around half the RPM's and be somewhat quieter? Also a little better gas consumption rate? How far off is my thinking?
Thanks,
RichH

17 Replies

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  • pianotuna's avatar
    pianotuna
    Nomad III
    Sep 12, 2015
    Hi, There are very few 6000 watt inverter generators. The Yamaha 3000 and the Honda even running flat out are fairly quiet. The 6000 may be louder at 1/4 throttle, which is generally where the eco switch moves the speed to under low load. If the 6k unit is rack mounted (and they are HEAVY) the noise will transmit through the frame of the trailer to the interior.

    The lower weight 3000 watt units can be deployed on the ground so that no noise is transmitted via the frame.

    Cost of operation may be higher on the 6k units.

    I'd add a hybrid inverter and run on the eco setting of the 3k generator.
  • RustyJC's avatar
    RustyJC
    Explorer
    Sep 12, 2015
    edhensley wrote:
    No the speed is set to deliver the proper line frequency, 60 cycles per second, 60 times 60 = 3600 RPM.


    True for a synchronous AC generator - speed is constant and torque varies with amperage. Depending on the number of poles in the generator, 60Hz synchronous speed can be 3600, 1800, 1200, 900, 720, 600, 514, 450, 400, 360, 327, etc. RPM.

    If you want RPM to vary with amperage, get an adequately sized inverter generator and run it on the Econ setting.

    Rusty
  • Mile_High's avatar
    Mile_High
    Explorer
    Sep 12, 2015
    You are asking on the 5th wheel forum, which are folks that typically have provisions for built in gen systems using LP. You probably would have better responses from the TT folks under Travel Trailer.
  • CarlT100's avatar
    CarlT100
    Explorer
    Sep 12, 2015
    My onboard Onan is 5500 watts and it runs everything including two ac's. I think a 5kw would work for you; most certainly a 7kw is more than ample. Generators use more fuel under load; but run at a steady rpm.

    I can power most of my house on a 7.5kw including a window ac unit. I cannot run my central ac/heat pump on it. If I need to use the microwave, I turn the window ac off. I can also shut most everything else down and run the water heater on the 7.5kw. These is our hurricane power.
  • Oasisbob's avatar
    Oasisbob
    Explorer
    Sep 12, 2015
    Please stay with a quiet quality unit. I maybecamping nesxt to you oneday.
  • edhensley's avatar
    edhensley
    Explorer
    Sep 12, 2015
    No the speed is set to deliver the proper line frequency, 60 cycles per second, 60 times 60 = 3600 RPM. By getting one that is over size you don't put as much load on the engine and the alternator. Good mounting or distance will do more for the noise.

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