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Forever bicycle light

 No batteries no power from a generator, just light
  (+2)
(+2) 		  [vote for,
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Currently there is a trade-off for bikers. They can use batteries to power their lights (bad for the environment) or they can use a primitive generator that rubs on a wheel (bad for biking performance). However, some smart person invented a flashlight that is recharged by shaking it (link). If such a flashlight is mounted in a bike frame - with LEDs mounted at rear and front of course - the normal bumps from the road will recharge the capacitor and keep the light going.
—kbecker, May 31 2004

Forever ligth http://www.thinkgee...adgets/lights/5a9f/
Link taken from [hippo]’s toothbrush idea, thanks [hippo] [kbecker, Oct 04 2004, last modified Oct 21 2004]

(?) Just how much power can a piezo element generate? http://www.piezo.co...-us/pg_71.html#app5
Possible, but some clever mechanical solutions needed to avoid breakage. [Ling, Oct 04 2004, last modified Oct 05 2004]

[link]






       yup, makes sense to use non-productive energy rather than all that leg power.
—neilp, May 31 2004
   

       I think that the shaking for that flashlight has to be rather longer strokes than the typical road, unless it is a dirt road with potholes. If you used a piezelectric element in the suspension it might work, as piezo stuff only needs tiny movements.
—macrumpton, May 31 2004
   

       I thought the main reason for such lights was to allow other people to see YOU, bb. I'm sure in such a case, bright LEDs would be plenty bright enough.   

       I'm not sure a simple capacitor would be enough to continually power the light here, though - some battery would be needed to store energy accumilated through the day, it seems to me.
—yamahito, Jun 01 2004
   

       I agree with macrumpton; the piezo devices would be very light. But I wonder if they could make enough power?
A rectifier and smoothing / ultra capacitor might be useful.
—Ling, Jun 01 2004
   

       Good idea to use the energy wasted vs. the inertia of the bike, but I think just taping a flashlight to it is not the answer.   

       Correct me if I'm wrong, but doesn't the energy still come from leg power? I might be confusing my physics here, and it's obviously negligable, but if negligable leg power can be converted to usable light, is there a more efficient way than through extraneous bike movement?
—Cheekio, Jun 01 2004
   

       [Cheekio] you are correct that the energy comes from leg power, but it is leg power that already has been converted into bump-power. The flash light would actually make the ride a little smoother because it would absorb some of the vibration back into electrical power and thereby dampen the vibration.   

       [Brau] I have not seen the light on people either, any link?
—kbecker, Jun 01 2004
   

       Couldnt this device be mounted on the spokes, and the power generated by the "thingy" moving up and down the tube when the wheel goes round and round? Power could be taken off by use of contact strips (or does this rob the power again?
—senatorjam, Jun 01 2004
   

       Why not replace the spring shocks altogether with a magnetic suspension system cum linear generator? That way you'll be recovering a large proportion of the bump energy. It should be enough to keep a light or two in charge. Maybe enough to trickle charge a phone/iPod/PDA/bike computer as well. And a smoother ride into the bargain.
—BunsenHoneydew, Jun 03 2004
   

       [zanzibar,braubeaton] of course the power would be apparently free until you ask the leg muscles if they are getting more fatigued now while paddling the bicycle under identical road conditions (bumps, terrain,distance etc.).
—vedarshi, Jun 05 2004
   

       I've been using such a device for years on and off. I just tape a couple of LEDs to a piezo disk, each LED in reverse, and then mount it on something that can flex. Bikes vibrate lots anyway and so the LEDs light up nearly all the time you're moving and they have motion blur too. Works fine. Amazes me noone's selling them.
—blackmath, Jul 13 2004
   

       I had that idea myself , I found a tail light and a "be seen" front light that are similar to what is being described here . its called reelight , I bought one for my son a few weeks ago . Somday someone will make one with a brighter headlight .
—sQWERTY_F_ALIEN, Oct 19 2006
   
      
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