Possible generator for hybrid rack/pusher

Discussion in 'General Questions' started by loquin, Feb 17, 2008.

  1. loquin

    loquin Active Member

    Ran across this 1000 W generator (2 HP, 2 stroke engine) that might be a possibility for the generator in a hybrid system.

    It looks like it has about a 1 gallon tank, which they advertise as running for 8 hours.

    It has a 12V trickle charger, a 12 volt outlet (180 W,) as well as a 120 VAC outlet. Neither of the two 12 volt outlets would be sufficient to keep an electric system charged while it is operational - you would probably need your standard charger hooked up to the 120 VAC outlet for this. (You might also have to do a bit of rewiring to allow your system to recharge while driving) However, it WOULD make it easy to hook up a decent 12V lighting system!

    Ref the blow-up pic below.

    Also, found what appears to be the same generator, rebranded, here. (63cc, 2-stroke, 1000W/1200 peak) but without the trickle charger. ref the second pic attached.

    Attached Files:

    Last edited: Feb 17, 2008

  2. So your saying have that whole deal on a pusher?
    Where's the PTO?
  3. loquin

    loquin Active Member

    No PTO. It's a small motor-generator. You would run a power cord to the batteries on an electric, to keep 'em charged. Which would convert an electric to a hybrid, (with unlimited range.)

    If I were doing it, I would make a trailer to hold the generator/charger. That way, you would run around on the short runs, close to home, without pulling the trailer. On the longer runs, you would hook up the trailer & plug it in, converting the electric to a hybrid.
    Last edited: Feb 19, 2008
  4. I was thinking more along the lines of having the engine driving the generator also driving the pusher with unlimited power to operate lights,air horn,ummm,neon lights,windsheild wipers...the imaginations would be endless!
    I just don't see this engine turning just for motor power.
    Now if you're talking about a high torque motor that needs a/c power capable of 0-40 mile speeds in two seconds then you may have something here.
    I do see where you're going here,though.
    I've love for you to explain to a cop that you're legal for it'e the electric motor that's pushing your bike down the bike trail and not the engine.
    I see the only real way of doing this because of weight is to make it a pusher with an automotive battery or a puller with motor on your bicycle wheel wired to the trailer. That way for a few miles you don't have to run your generator,then have it so just generator power will run your bike with some power to spare to charge up your battery.
    Yes. That would be a hybird.
    Last edited by a moderator: Feb 19, 2008
  5. loquin

    loquin Active Member

    If you install a standard electric setup, and use the generator to keep it charged, you could demonstrate it to the cop - turn off the generator & drive off with the generator not running. They'll go 10-20 miles on a charge, after all.
  6. cooltoy

    cooltoy Member

    Hi, Loquin, I was just on my way to start this topic on a new thread but you beat me to it. Great job so far,thanks!
    I know there are a couple of electonics guys here as I've raed the posts so I hope they come on board as well
    I had what I thought was a really good electric bike (e-bike) but I sold it within a few weeks because I spent more time charging than I did riding. That was when I started to think Gas. What you mentioned above would solve this and I can't come up with any reason that is would not work.
    I would like to ask why we could not use an electric motor, a dimmer switch for speed and the generator to power it. I know the dimmer switch would get hot and blow up but this is the best way to tell others how I see my project working.
    This could be done for under $250 and would last for years because electric motors seem to last for ever and the same could be said of a generator.
  7. Yes......yes...

    Attached Files:

  8. cooltoy

    cooltoy Member

    Love the smile on your face !!!!!! I can just see your "gears turning". Seems to me that this could be built in one afternoon and for me the throttle is the only thing that I don't have a clue about. Think about how long a 110 volt motor could last man!
  9. loquin

    loquin Active Member

    You'd want a variable speed motor control. A lamp dimmer isn't going to cut it when driving an inductive load like a motor. A variable speed motor control works by varying the frequency of the output voltage, and is known as a VFD (variable frequency drive)

    Lamp dimmers work by interrupting the AC power cycle on each positive and negative pulse. Suppose it's set to 30%. After 30% of the power from the positive-going half of the cycle is delivered, the smooth sine wave is chopped off. Then, half an AC cycle later, after 30% of the negative-going AC cycle is delivered, the sine wave is again chopped to zero.

    The problem is this. The motor has a lot of coils of wire, which the AC line has energized to form a magnetic field. When the power is chopped off, that magnetic field collapses. When it does, as the magnetic field goes to zero, it is moving past that same set of coils. A moving magnetic field, coupled with a coil of wire, causes a spike of voltage in the coil. This voltage spike is called "Back EMF" (as it is electro motive force that is sent back up the lines) and it can be many hundreds of volts - enough to fry electronics, especially when repeated 120 times a second (60 positive spikes, and 60 negative spikes a second)

    Here's the other problem: Most motors used in homes are induction motors. They work well, and they last a long time, but only because they operate at a fixed speed. They have an internal fan, used to circulate the air inside to keep them cool. However, a slow moving motor doesn't move the air fast enough to stay cool. This is why electric motors tend to burn out in low voltage (brown out) conditions.

    So, unless you find an AC motor that is rated for use with a variable frequency drive (VFD,) which is expensive, you'll be better off using a DC motor.

    Note that most treadmills use a DC motor with a speed control...
    Last edited: Feb 19, 2008
  10. loquin

    loquin Active Member

    Here's a possibility at EBay - a half horsepower 120V DC motor.

    Now, electric motors give more usable power per HP than do engine HP. Odd, but true. This .5 HP electric motor is the usable power equivalent of a 1 to 1.5 HP gas engine.

    With this motor, you SHOULD be able to use a lamp dimmer. Take the output from the dimmer, feed it through a 10 to 15 amp bridge rectifier to convert AC to DC, then to a large filter capacitor. The motor would be wired in parallel with the capacitor (which would filter out the back EMF pulses). You would have to gear things down a bit though... 10000 RPM at 120 volts ;)
  11. OOOH friction drive!
  12. loquin

    loquin Active Member

    :grin: with a 5/8" drive spindle!
  13. cooltoy

    cooltoy Member

    Glad to see that you guys have not let this thread die off and am so happy to see that we have an electronics expert on board.
    As for the dimmer switch, I only used that as a way of getting feedback but now you seem to be saying that it is possible. What about that other speed control you mentioned yesterday? What would the cost be, do you have any idea? Also, did you think that the small motor that you showed us on E-bay is the right one only because I had mentioned the Dimmer switch? Is a motor as big as the one pictured in that pic from Large Filipino too big?
    I will build this once things warm up a bit and hope that "we" work things out as far as plans go.
  14. skyl4rk

    skyl4rk Guest

    Thanks for the link to the charger, that is really cheap!

    Here's how I would use the charger on a trailer:

    With an existing 36V hubmotor / lead acid battery system, wind a transformer to drop the 120VAC down to about 45VAC, more or less. Then run it through a bridge rectifier capable of maybe 5 amps or better and add a couple of big capacitors across the + and - to smooth out the pulse DC. Check the final DC output voltage and adjust the number of turns on the transformer so the output DC voltage is at the trickle charge voltage for the battery pack, which is going to be about 40DC (I need to check that).

    What will happen when you are starting from a stop (which causes the highest amp load on the battery) is that the generator system will be covering the first couple of volts of voltage drop, and the battery will cover the rest of the voltage drop. At higher speeds when the voltage drop is not as high, the generator will be providing most current and may also be able to charge the battery, although the battery may kick in under acceleration or on hills.

    This would be a way to build a true hybrid, in fact a three way hybrid, gas, electric and pedal.
  15. It would be cool too if the generator self started according to load,just like on a hybird car.
  16. loquin

    loquin Active Member

    If you want to go high tech, rectify the 120VAC & Filter it. This creates a +/-170V DC power source. Then, add a high voltage push-pull switcher circuit, the output of which will feed through a small, high frequency step-down transformer, approximately 5:1. Then, rectify and filter this voltage. Use a comparater circuit to compare the output voltage to apx. 43 volts, and use this as feedback to to modulate the width of the switching pulses. This is a classic pulse-width modulation power supply, and is highly efficient - in the 95% efficiency range. In addition, because stepping down a high frequency AC signal is so much more efficient than a 120 hertz waveform, you can use a tiny toroidal transformer, smaller than a hocky puck, meaning that the power supply can be much, much lighter than a 120 volt power supply of equal current rating. (You can also, if you wish, add a secondary lower voltage coil to the main transformer that would use standard regulation circuitry to produce a +12V output)
  17. loquin

    loquin Active Member

    A VFD is pretty expensive. Low-power units, for motors up to a horsepower or so, were in the 200-300 dollar range the last time I bought any, about 10 years ago. Plus, the motors themselves have to be rated to be used at low frequencies, (and therefore, lower speeds, and less cooling) and are more expensive also. Your standard AC motor won't cut it. (Edit: here's a link to fractional HP "off brand" VFDs - a .5 HP unit is $189)

    That other motor, from EBay could also be used as a DC generator, if you wanted to hook it up to a small gas engine. Or, it could be used to drive the bike. It needs 120 VDC though to develop full power though, which could be supplied through a lamp dimmer/rectifier circuit, as I mentioned above.

    However, in order to be a true hybrid, you would need 120 volts worth of batteries to push it to it's maximum output, plus a different control circuit. Probably a control circuit based on high speed switching and pulse width modulation, similar to what I described earlier, if you want to wanted to remain fairly efficient.

    cooltoy: That'sDax also has a background in Electronic Engineering. There are probably others here as well
    Last edited: Feb 20, 2008
  18. I need to take a nap now. That's so much to absorb.
    Imagine someone actually figuring this all out.
    Imagine the wealth yet to be aquired.
    I would buy one,just for the cool factor and for the telling the roadie on the bike trail how your bike is legal.
  19. skyl4rk

    skyl4rk Guest

    Do you know if this is how hybrid car systems work? I have been trying to find information on hybrid systems and have not found much.