stoopid (on-topic) question about 120V generators and motors

Discussion in 'Electric Bicycles' started by augidog, Feb 20, 2009.

  1. augidog

    augidog New Member

    i have a 120V/600W/4.2A gasoline generator. it also has a 12V/8.3 outlet. it's an old mcculloch "power-pac" in great shape, compact but heavy.

    i'm thinking "120V motor" but that's about as far as i've gotten with this...

    worksman industrial trike
    generator & motor in the bed
    belt-drive to axle

    i think 4.2A isn't much. is this doable? yeah, but is it worth it?

  2. bluegoatwoods

    bluegoatwoods Well-Known Member

    4.2 amps @ 120 volts would come to 504 Watts of power.

    Maybe that's not huge, but it's not terrible either.
  3. Brad883

    Brad883 New Member

    I've been toying around with a similar idea. Kind of a bicycle take on the diesel-electric locomotive. Not sure if it's worth it, but it would be neat to try. First I gotta find a trike. (OK first I have to finish my motored bike, then the trike...)
    Last edited: Feb 21, 2009
  4. cooltoy

    cooltoy Member

    I've also tried to get input on this subject many times but it always seemed as if the interest was not there.
    I hope that all the electrical wizards pony up to the bar this time.
    I've always wondered about a generator push trailer running a 120 volt motor or having it's 12 volt output charge an electric bike.
    With the way some of the frames are built on these generators, you could just mount wheels , or even a driveline to it , along with a hitch and your good to go.
  5. augidog

    augidog New Member

    hey, some interest!

    i've considered charging a bank of batteries, but the overall weight would be too prohibitive, imo...the "diesel-electric" concept is interesting enuff to, i go looking for what, a 500W motor? or should i go slightly smaller to avoid running out of power?

    what's my options if i use the generator to power a 24/36/ or 48V power supply? better motors?

    i know this is a crazy idea...the worksman is slated for an "exhibition" build, something crazy fast...if i can't get the results i want with the electric, i do have a 177cc wisconsin-robin.
    Last edited: Feb 21, 2009
  6. skyl4rk

    skyl4rk Guest

    It should work, it would probably be best connected to a 120VAC motor with no battery. 500W is not a lot but certainly enough to move a bike.
  7. JinbaIttai

    JinbaIttai Member

    Not worth it.

    Consider that your generator is really just a combustion engine that turns a shaft that turns a generator.

    Imagine removing the electric generator portion for a minute. Nothing but an engine that turns a shaft. Now your goal is to try to find a way to get as much energy from the turning shaft to the rear wheel as possible.

    Why not just couple the shaft right to the wheel of the bike?

    Having it turn a generator which then turns the wheel puts it through a couple of extra energy-wasting steps, and you still have to come up with a motor and wiring.

    The only way adding a "middle-man" between the engine shaft and the wheel would be better than none at all is if it somehow had like 120% efficiency, which isn't possible.

    Edit: Then there's the thought that the generator is running at an ideal fixed RPM suited for best fuel consumption as it is.

    I don't know if this is true or not, but if it were run with the generator part removed there wouldn't be any throttle control.
    And adding a throttle would defeat the point of having that "sweet spot" RPM for fuel consumption.

    Maybe with the right gearing and a clutch, you could ride it as a constant RPM engine assist.
    Last edited: Feb 21, 2009
  8. augidog

    augidog New Member

    we have joked around about a trike zooming by at 30mph, the generator at a smooth "idle"....that would turn some heads, alright.

    efficiency is not a factor, it was the novelty that got us thinking...if we can't get some crazy performance outta it, it won't be worth it...noone up here in their right-mind would dismantle a good generator, we have enuff outages to make it a necessity.

    thanks for the input :cool2:
    Last edited: Feb 21, 2009
  9. skyl4rk

    skyl4rk Guest

    Give it a try, there are a lot of old 120VAC motors to be scrounged, weedwhackers, washing machines, ...
  10. srdavo

    srdavo Active Member

    augi.... I vote, give it a shot.
    keep thinking ...locomotive... produce 110v. to a 110v. motor.... gear it right & go!!
    Leave the naysayers in the dust!!
  11. augidog

    augidog New Member

    it's too easy to not at least try, i think...

    job one is gonna be stripping 15 years of orange housepaint off the entire thing. i expect this is gonna be great "occupational therapy." job two is putting some serious rake to it, chop-n-drop, an old-school rat-daddy dragster...track-only material. after the chassis' ready, mounting a scrounged motor to the cargo bed is a cinch. the axle already has a long flat for set-screws, so installing a sprocket or pulley ain't no thing. if it doesn't pan-out, we're not committed.

    davo, it's the gears, this is like electric 2-stroke theory? ok, what kind of productive rpm's we talking about?

    like, i know what the 24V/400W currey but not enuff for this job...120V/400W is faster, or stronger? both? neither?

    this is gonna be a stout vehicle, something that'll handle some serious power.
  12. skyl4rk

    skyl4rk Guest

    400W is 400W. Expect some movement but don't expect to burn rubber. You might gear it down 10 to 1 (more or less), the motor might appreciate that. But it depends on the motor. Electric motors generally will have a very wide useful rpm range. But they don't like to run at very low rpm. So gearing it down will let the motor run at a higher rpm while you still get the torque you need as rubber meets the road.
  13. augidog

    augidog New Member

    s'what i thought. shoot...maybe 12mph with big reduction. nope, wouldn't be prudent.

    but we still could wind up trying this someday on something suitable...if we do i'll dig this up and update...

    thanks folks :cool2:

    EDIT: any gurus know if i can gain usable amperage by (dc-dc) converting to a lower voltage?
    Last edited: Feb 22, 2009
  14. skyl4rk

    skyl4rk Guest

    Your generator has an ac output and ac motors are lighter and very efficient. Why go dc?
  15. augidog

    augidog New Member

    that's why the subject-line sed "stoopid question"...i'm a total electric-idjut.

    so bottom line is, with this particular generator powering a motor, it would barely be able to get out of it's own way.
  16. srdavo

    srdavo Active Member

    your Currie motor is prolly 450w.

    do you know what rpm's your a/c motor spins?
    Last edited: Feb 25, 2009
  17. augidog

    augidog New Member i mentioned, the currie's impressive, but it's still not enuff to slam a trike down the track.
  18. electraflyit

    electraflyit New Member

    Motor running generator running motor.... yes.... it is done right now in some hybrid vechiles.
    Electric motors give maxium torque at take off then the fuel motor takes over and holds the speed. Excess power from the fuel motor can recharge the batterys as can regenerative braking.
    The fuel motor is optomized for efficency at a certain RPM and load, the high power/torque times are when the electric motor comes in and helps out.
    If they can do it in a car we can certainly do it for a bike or trike.
  19. duivendyk

    duivendyk Guest

    Forget the electricals,too much weight and too inefficient,this thing is prob.supplying 120V ,60 cycles and is governed to run at 3600 rpm.600 Watts is about 0.9HP so there is no power to waste.Is this a 2 stroke?.You could prob. get more power out of it at higher rpm.Any idea what the displacent of it is?