Bottle generator set up [maybe]

Discussion in 'General Questions' started by recumbentbill, Dec 14, 2007.

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  1. I would like to incorporate my more powerful than average bottle generator on my GEBE/Tanaka powered MTB. The bottle generator I have is a pricey $$ Dymotec S12that powers a 12v lumotec Halogen oval plus light and tail light. I bought this generator for use on my recumbents and used it for one night only. WHY--Because it has a lot of drag. I like the bright 12volt light that it produced but the drag was a drag. I went back to my SON hub dynamo. I wonder if having the bottle roll on a smaller diameter disc or pulley [say 10"dia maybe] that would be mounted to the front spokes would work. I'm thinking that the smaller diameter would not burn up either the bottle or the bulbs. input or feed back is appreciated.

  2. Egor

    Egor Guest

    Bill - Does it matter on the motor bike? If so I guess it has a lot of drag. If you run it on a smaller circle it will produce less drag but there might not be enough power. I have often thought of running one off the engine but you would have to keep it in RPM range. Have fun Dave
  3. BSA

    BSA Guest

  4. Bottle Generator

    Thanks for the input Dave
    I'm not concerned about the drag on a motored bike .I'm concerned about running the generator on the side wall of the tire on a bike thats going 30+mph. I thought that by having the gen rolling on a smaller diameter [traveling at 30mph]just might be equal in out put to the gen spinning at 10 to 12 mph under human power with the gen monted in the normal postion in contact with the tires side wall.
  5. Thanks BSA I looked at the thread you mentioned and they are about the happy time bikes that have a magneto. My GEBE/Tanaka does not have a magneto. Even just using the bottle to charge a battery I'm concerned that the bottle will be spinning to fast at 30mph
  6. jpilot

    jpilot Guest

    It doesn't seem like it would be very difficult to reduce the speed of the generator by just installing a larger drive roller on the generator. Maybe a model car wheel or something similar. Doubling the diameter of the drive roller would halve the RPM. Power output would, of course, be reduced.
  7. Sianelle

    Sianelle Guest

    I use a vintage English Miller 6volt 'bottle' dynamo on my electric assisted Hercules tricycle and I have quite a collection of 50+ year old English and German made dynamos, including some hoary old monsters intended for use on autocycles. In the 'Heroic' days of bicycling some degree of control over the speed a dynamo rotated was obtained by increasing the diameter of the knurled drive roller relative to the size of the bicycle wheel.
    I ride my 28 inch wheeled traditional heavyweight roadster bicycles on a regular basis and I've always been careful not to use a dynamo with a small drive roller on a 28 inch wheel for the simple reason that the dynamo will (a) overspeed. (b) chew the living daylights out of the tyre.
    Bottle dynamos do drag, - the electrical energy has to come from somewhere afterall, but it's all win-win when it comes to using one on an electric powered trike.

    I would suggest continuing to run your modern Dymotech in the traditional way, but it could be well worthwhile to explore making a larger drive roller for it to reduce its working speed. I don't understand elec-trickery myself, but I understand it is possible to make a basic voltage regulator to use with a dynamo. Back in the 1980s I can remember the local bicycle activist magazine having circut diagrams for this kind of thing.
    An example:

    I would suppose your Dymotech lacks for such things as oil or grease cups and can't be dismantled for servicing the bearings (sigh).......