Another Light Fix

Discussion in 'Spare Parts, Tools & Product Developement' started by RedGreen, Dec 6, 2008.

  1. RedGreen

    RedGreen Member

    I am sure everybody here has tried to use the bicycle wheel rubber generator.
    I came up with two thoughts, to neither do I have the complete answer.
    First is, instead of using the tiny original wheel for the generator, have made up a much larger one that will fit in it's place. That way it should turn slower and not burn up.
    Second. find a small generator and have it rub against the wheel by cutting a slot into the top of the rear fender to allow it to poke through.
    Obviously, there are a number of problems to this idea. First is where do you find such a thing, I would think the smallest auto generator would be way too big.
    Thoughts?
     

  2. I thought about a larger wheel as well but integrate the generator to a battery that powers those power wheel toys then your lights stay bright no matter how fast or slow or stopped you are. Then with the larger generator wheel it's not asked to generate max output and even at top speeds with the wheel large enough even 3/4 power max would be plenty. Even during the day you can run that generator with less drag and lights off. I ride mostly during the day as probably most but if your commuting on the way home when it gets dark at 5:00 epic win.
     
  3. SirJakesus

    SirJakesus Guest

    I've heard they burn out at MB speeds as well. Any idea what actually wears out on them or is it just the extra current burning out lights?
    Automotive generators would probably put too much drag on these small engines, I would think something like a light ride-on lawnmower generator would be more appropriate. I have a 12v bottle generator that I've been planning on incorporating into my bikes electrical system. I was just going to build up the wheel with some epoxy in a mold and finish it with a dremmel. I think it would be near impossible to find larger replacement wheels for these things.
     
    Last edited by a moderator: Dec 6, 2008
  4. heathyoung

    heathyoung Member

    Has anyone thought of using a front hub motor as a generator? They are rated at 200W, and are fairly effective generators at low speed as well due to their construction. They also work well as brakes when shorted (oops!)
     
  5. RedGreen

    RedGreen Member

    I spoke with a supplier of the hub generators and they seemed to think that they would overheat and burn out at Motorbike speeds. That may be incorrect but there it is
     
  6. heathyoung

    heathyoung Member

    Not a hub generator, but a hub motor, as per electric bike conversion kits.

    Get a 200W one, make yourself up a rectifier (they usually have 3 windings) and you could run a fair bit of lighting without too many problems.

    There are some out there that are just brushed DC (not brushless) that produce a suprising amount of power! Brushless requires a rectifier (as I stated before) but work better at lower speeds. A regulator of some sort will be neccesary as the voltage output at high speeds will be HIGH - in the region of 36-48+V!
     
  7. RedGreen

    RedGreen Member

    NEAT!
    I had wondered if you could do that. I would think even the smallest motors could make enough for lights
     
  8. heathyoung

    heathyoung Member

    They work well as generators, very powerful permanent magnets but you need a 3 phase rectifier for brushless - eg. http://www.allaboutcircuits.com/vol_3/chpt_3/4.html#03267.png - a simple bridge rectifier will work for brushed.

    Use diodes that can withstand the current and voltage you will be running, you can strip out a rectifier from an old car alternator (you cant use the reg though, they work by varying the stator current - ie adjust magnetic force to adjust voltage.
     
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