Electric-gasoline hybrid.

Discussion in 'Laws, Legislation & Emissions' started by motorbikemike45, Feb 15, 2010.

  1. I'm considering building an electric-gas hybrid using one or perhaps two hub motors driving off batteries and using a gas engine driving an alternator to charge the batteries. My question; Since the gas engine is not driving the wheels, is the size limit on gas engines applicable?

    I might mount the gas engine-generator on a trailer, only hooking it up for longer trips than the batteries would last on their own. It seems to me that since the gas engine is not involved in actually driving the wheels, it's nobody's business what size engine I use to recharge the batteries. The legality of using a gas engine larger than the law allows for a MB, if it is used only for recharging the batteries, is what I am asking opinions about.

  2. loquin

    loquin Active Member

    IMO, it should be treated as an electric assist bike. And, if you were stopped by an officer, you could prove this by shutting off the gas motor, and demonstrating that the bike could still run off the batteries. Note however, that you could probably easily stay below the 50cc limit and provide the power you need to keep the batteries charged, as the average power requirements should be below the 750 watt limit as well.) The only reason for a bigger gas motor in a gas-only bike is for acceleration and hills, as on the level, one HP could keep you moving at up to 30 MPH.

    Along the same lines as you've mentioned, I've always thought that, if someone had an e-car, you should be able to buy (or, for that matter, rent) a small trailer with a 15-20 HP motor-generator set, when you needed it for long distance travel...
  3. professor

    professor Active Member

    I agree with Lou about the legality thing. I looked at the new e-bike law here and there is nothing I see to prohibit doing exactly what you are proposing.
    I am going stealth though- out of sight - out of mind.

    I went with a HF79 with your same thought in mind- could be a small block chevy if it wouldnt get noticed. 'Course the HF is a lot cheaper.

    Here is the deal with engines powering the alternator-
    The big engine is not screaming away(around 3 grand) to run the alternator. I like quiet and the more relaxed rpm of the HF.
    I am running a one to one ratio and the HF has just enough power to run it-
    I tried a 49cc and a 98ccTechumseh- neither had enough umph. Maybe at a different ratio to get them into their power band... But then they will be really singing- and probably loud.
    A Briggs would surely work well (a guy on the net sells a gen. kit based on the briggs and a delco). But a Briggs is too big to fit in my frame, thus the HF.
    A smaller 4 stroke would have to be ratioed different than one to one, I think.

    A note on voltage: A 24volt regulator for the Delco is available on Ebay. They are used in diesel and in marine applications, Higher ones are not available.
    An armature that has permanent magnets is available ($130) to do away with the field circut and allow for higher voltages. But you will have to regulate voltage with rpm somehow.
    I say this because you might be thinking of 36 volt motors for you bike.
    By the way I don't mind the 450 watt motor at all, but am only geared for around 15 mph flat out.
  4. SimpleSimon

    SimpleSimon Active Member

    I am working on a tadpole recumbent design, professor, with an engine/genset behind the seat, but I'm doing it a bit differently. Basically, the e-drive will be both of the front wheels by hub motors, total wattage is 700, with the chain drive going conventionally to the rear wheel. In order to avoid wheel scrubbing in corners due to differential effect, I am going to do an arduino based throttle control, with a turn sensor built into the steering linkage, so as to apply power differentially to the hub motors for cornering.

    Pretty straight forward, really - the turn sensor being the most critical component. It has to be reliable and robust.
  5. professor

    professor Active Member

    Simple, I really doubt you need to go to all that effort with steering. When you go to turn - one motor will just be loaded more than the other. It's not like they are geared together.
    I do think twin drive is a great idea, how about a controller for each motor using a cable down to a place on the bike where you could join 2 thumb throttles. This way, if there was a failure on one system- you still can fly, plus, 2 500 watt controllers are likely cheaper than one 1000w unit.