Swamp Cooler Motor for Electric Bike

Discussion in 'Electric Bicycles' started by Wayneburg, Jun 1, 2010.

  1. Wayneburg

    Wayneburg New Member

    Has anyone tried making an electric bike using an electric motor from a swamp cooler? These motors seem powerful enough to do the job. And they're pretty common in my area, sometimes even free. Just thought it would be worth asking.

  2. safe

    safe Active Member

    Swamp Cooler Motors are (to the best of my knowledge) about the same as dishwasher motors. They run on AC current and tend to be built rather heavy for ebikes.

    I've actually tried to take a motor like that and disassemble it and rewind it to run at low voltage DC, but after studying the math on it I realized that though it can provide a WIDER powerband than simple magnet based motors they tend to not be as efficient.

    You are better off buying a regular motor.
  3. wheelbender6

    wheelbender6 Well-Known Member

    The AC motor may run well with an on-board portable generator.
  4. safe

    safe Active Member

    There was a project created over on ES which used an AC Induction motor of the same category and they used an inverter (the sort of thing you plug into your cigarette lighter in the car) to take a 12VDC battery up to 120VAC. It worked... it was really, really heavy, but it worked.

    The Tesla Roadster uses an Induction motor and over a year ago I was all excited about the idea of doing it for ebikes, but Induction motors seem to find their efficiencies when you get up into the 100hp range. Below 100hp and it's hard to get above about 80% efficiency. By contrast the Halbach type CSIRO motors can reach near 96% efficiency and with far less weight.

    To enhance efficiency I looked into Six Phase power as one way to boost performance and I actually bought a dishwasher motor and began to convert it, but the math just doesn't add up on these things. It's a lot of work to go backwards technically. (however the wider powerband of induction motors is appealing... you can get full power over an rpm range that is twice of a permanent magnet motor)

    High powered Neodymium magnets combined with a Halbach array configuration Axial Flux motor seems to be the most high tech solution for an ebike and while we're not there yet it's the way we are being pointed to based on the facts.
    Last edited: Jun 2, 2010
  5. Neon

    Neon Member

    Wouldn't finding a controller that worked with an AC motor be a bit of a problem as well?
  6. loquin

    loquin Active Member

    They're out there, and are fairly efficient. But, they cost $$$. Google "Variable Frequency Drives" aka VFDs. They are commonly used in industrial processes. The cheapest that I've seen for small, 1-2 HP units are in the $150 - $200 range.

    BTW. some of these drives can convert a 1 phase input to 3-phase output, which would enable you to use a small three-phase motor. 3-phase motors have great torque and are less expensive than equivalent 1 phase motors.

    However. The 'system' would have to include:
    1. Batteries
    2. Inverter (DC-AC)
    3. VFD (the link is to a spec sheet of a VFD that might work for this app.)
    4. Throttle potentiometer
    5. Motor
    6. Metal housing for the drive. (it HAS to stay dry, and it needs to dissipate about 50 watts of heat.)

    And, you would need to consider the additional losses in the VFD. At 100% output, the VFD above is about 95% efficient. At lower outputs, the efficiency is less. The inverter also has losses to consider.
    Last edited: Jun 2, 2010
  7. Neon

    Neon Member

    As safe mentioned this is way to bulky and heavy a setup for a bicycle. Not to mention far too complicated. Sounds like this setup is more at home in a e-car where there is room to put everything and the extra mass will not be noticed as badly. Of course the heat generated could be used to help heat the interior during the winter.