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Topic: Small powersource based on motion needed! (Read 10007 times) previous topic - next topic

dieselboris

Hi all,

Dunno whether this is the right place to ask this but i'll give it a try.

I want my bicycle light to be powered on the sideways motion of my bike. For this i would need a device which is also in 'automatic' watches like the seiko kinectic (they do not require battery but winded up by the motion of the wrist).

Does such a thing exist in electrical form (the watch version being mechanical)? And if so, would the power be large enough for a LED to burn?

Thank you! 

Far-seeker

It's possible, but you'll have to use at least a small rechargable battery. Otherwise the energy will be produced too intermittantly and likely in amounts too small to continously run one or more LEDs.

Piezoelectric vibration sensors can be used as small-scale energy harvesters.  If you go this route should use a dedicated energy harvester IC, like the LTC3588-1.  Sparkfun sells a small circuit board built around the LTC3588-1, you'll probably find other options after a little googling.

wanderson

I would be surprised if a bicycle that stays upright would have enough sideways motion to generate useful power for a light.  Please let us know what you find when you start testing.
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dieselboris


I would be surprised if a bicycle that stays upright would have enough sideways motion to generate useful power for a light.  Please let us know what you find when you start testing.


i'm hoping for the sideways motion when you're accelerating. The primary target group are those fixed gear track bikes. But i'll let you know if anything comes out!

Grumpy_Mike

Well I would say you have no chance to get this to work. Have you seen those torches that light with reciprocal motion you get in Discovery shops. That gives you some idea of the mechanical to electrical conversion rate you can expect.

Far-seeker

After some thought, an alternative came to me.  Why don't you just use the bike chain to rotate a small generator/alternator?

dxw00d

Bicycles have had dynamos for decades. Why not use one of them?

http://en.wikipedia.org/wiki/Bicycle_lighting#Dynamo_systems

dieselboris


Bicycles have had dynamos for decades. Why not use one of them?

http://en.wikipedia.org/wiki/Bicycle_lighting#Dynamo_systems

because i want to avoid wiring over the bike ;)


After some thought, an alternative came to me.  Why don't you just use the bike chain to rotate a small generator/alternator?

Do you think that would produce less friction than a dynamo on the tire? Definitely something worth looking into!

Far-seeker

What I was actually thinking of would be similar to the "bottle" type dynamo, only DIY and perhaps using a cheap DC motor.  As an aside, most rotary electric motors can be used to generate electricity when the motor shaft is spun by an external force, though they are often significantly less efficient than purpose-built generators.

Also, if you decide on using a generator, commercial or DIY, I don't see how you'll be able to avoid runing at least some wires on your bike.  Slip rings can help in places where you have rotation, and might be included in a commercially available design.  If you do go the DIY route, here is a link to a couple that are convivial with a limited budget and could fit this application. 

beer lover

this is what I would like to build for my bike for lighting
http://www.instructables.com/id/Contactless-dynamo-powering-bike-safety-lights/

let me know if you make this.

thanks
bryan

retrolefty


After some thought, an alternative came to me.  Why don't you just use the bike chain to rotate a small generator/alternator?


Ever ride a bike? The answer here is no, because you would not be generating anything if you were coasting down a long hill unless you pedal constantly. Who wants to have to pedal going downhill?  ;)

Far-seeker



After some thought, an alternative came to me.  Why don't you just use the bike chain to rotate a small generator/alternator?


Ever ride a bike? The answer here is no, because you would not be generating anything if you were coasting down a long hill unless you pedal constantly. Who wants to have to pedal going downhill?  ;)


I meant that as an alternative to a purpose-built hub or bottle generator, there would still need to be a battery. :P

dieselboris


Ever ride a bike? The answer here is no, because you would not be generating anything if you were coasting down a long hill unless you pedal constantly. Who wants to have to pedal going downhill?  ;)


Here, we don't get to go downhill (or uphill for that matter).

Thanks for all the input, i'll go for a regular dynamo, it would need to power an arduino as well....

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