Questions: generators, coils, huh?

Discussion in 'Electrical' started by IASheer, Jul 25, 2011.

  1. IASheer

    IASheer New Member

    And here I am again, guys. More questions. I have been trying to search for answers, but when you don't know if the search terms you're using are the right ones, well... yeah. You get the idea.

    Anyway! Enough rambling!

    So I have a spooky tooth cycles 4g kit I got in 2010. I got it put together earlier this year, had transmission issues, then fixed them (with help from OCScully) and now that my bike's all roadworthy again, I obviously must try to break it! ^_~

    In short, I want to set up an electrical system for the bike. I realize that yes, every electrical build is unique, and so I'll probably have to fabricate it myself. Sure. For now, I'm trying to find out what I need, and what stuff is.

    So firstly: Generator. Do these 4-strokes have them? How do I take advantage of it if they do?
    Second: I'm in Arizona, and I'm always riding on the road. So that means no need for suspension, and I wanna take advantage of Solar for every chance I get.

    Third: I looked around, and found an in-hub generator for a bike's front wheel. The Shimano Nexus one, over at . Would something like that work?

    Fourth: I spotted a key-type electrical switch at Fry's electronics. Can I wire it into the motor to act as a killswitch (no key in lock, no motor running) kinda thing?

  2. GearNut

    GearNut Active Member

    Engine has no generator.
    In hub generator is an excellent choice.
    Any ignition switch could be made to work. The trick is keeping the wires well protected so it is difficult to hotwire.
  3. IASheer

    IASheer New Member

    Thanks for the tip. I'll look around for components.
  4. pbeggs

    pbeggs Member

  5. loquin

    loquin Active Member

    I've got the S/A one, and like it a lot. Keep in mind that you'll need to rectify the AC output from the hub to convert it to DC - I would suggest using 4 shottky diodes, as they have about half the forward voltage drop as standard silicon diodes.

    You're limited to 6-9 watts though, so you'll want to feed the power into a battery charger circuit, and feed the lighting from the battery.
    Last edited: Jul 28, 2011
  6. abikerider

    abikerider Member

    These hub generators all put out about 3 watts at 6 volts. Not a whole lot of power. I am working on a bolt-on magneto generator that puts out 3 watts at idle and 8 watts at maximum revs. It will cost less than those $100 and over generator hubs.
  7. loquin

    loquin Active Member

    At speed, the hub generators are good for about 6 watts. The 3 watt rating is at an average speed of about 8mph.

    and depending on the vendor, you can find the dynahubs for less.
    Last edited: Oct 14, 2011
  8. abikerider

    abikerider Member

    I stand corrected.

  9. birdmannn101

    birdmannn101 Member

    You can build your own rectifier (in a 1 inch by 1 inch plastic box) with diodes from Radio Shack. I used this on a Honda S-90 I restored which runs on a 6 volt battery. Send me a PM for details....Dan

    Attached Files:

  10. loquin

    loquin Active Member

    Really, because of the low output/power of wheel-driven dynamos, you don't have any power to waste, so you shouldn't use standard silicon diodes. They have, at minimum, a 0.6 volt forward voltage drop across each diode, and this voltage loss is doubled to 1.2 volts in a bridge circuit (as each half of the AC cycle is fed through two diodes serially in a bridge circuit.) Instead, as I mentioned earlier, get 4 individual shottky diodes, as they have a forward voltage drop of about 0.3V each.

    Ref the attached schematic.

    Note that the RMS (effective) voltage of a 6 volt AC, after conversion to DC using a silicon diode bridge rectifier is 5.2 volts, whereas, after a schottky diode bridge, it is 5.6V

    Silicon diodes are fine when used for rectifying the output from a dynamo that puts out 40-50 watts (or more,) as you would get from a small motorcycle engine electrical system. It provides enough power to waste some.

    Attached Files:

    Last edited: Oct 18, 2011