How to Charge Any USB Device by Riding Your Bike

Step 10 Finish!

Thanks for reading our Instructable, if you have any questions feel free to ask.

Here are some of the pictures from our presentation at MIT.

Comments

[importsonly]

JeffB you should try marking this item, make to usb ports one for a Ipod and one for the mobile phone, I know heaps of people that would buy a simple idea like this.. Good Job :)

[joshnosh]

not at over >$280 they wont you would be a moron to buy this lol

jeffB considering you have used a ridiculous motor for this project i think the constructive criticism off kagetsujki is quite apt.
if you don't want people to sit on top off a mountain criticizing then don't give them such a big mountain

[infomet]

Dear Jeff, You need to grow up. Kagetsuki was right on and not offensive, in my opinion. Engineering is engineering and feelings don't count. This is a fine project, stupidly implemented. If you are going to do electronic projects, you should have a competent advisor involved. There are MANY little DC motors that would be fine, but you didn't bother looking for one. The bike dynamos are fine, but your rubber tired pickup wheel is better than their toothed one that runs on the tire. They usually have a latch to facilitate taking them off the wheel when not needed. The point here is that you have to DESIGN the wheel diameter/motor combination to produce the current you need at the speeds you expect to ride. This will dictate a fairly high voltage permanent magnet motor and a regulator to produce the proper charge voltage AND CURRENT. At high speed, you'll be wasting some energy because of the high voltage produced, but at low speed you'll still be charging. You also need a current limiter in the circuit, because really dead batteries will draw excessive charge current if placed across the normal full charge float voltage. No doubt the commercial charge circuit does all this, but it might be missed by someone starting from scratch. More importantly, the dynamos are AC generators, so using one would require a bridge rectifier before the voltage regulator. And what's the point of the supercap? If you are making short trips, it will indeed produce more total charge (although not a lot), but if the trips are long enough to charge the device, then it's redundant. BTW, this fine idea could be used to produce chargers for your laptop, portable radio, or TAZER gun, or flashlight, with minor modifications. Best wishes from a very old engineer with many mistakes to his credit So there you go. $10 motor/dynamo, 50 cent rectifier (maybe), $5 regulator parts, and $4.50 slush fund for extras or beer. Then you get a reasonable design, learn something, and maybe a beer.

[name101]

I personally thought that the Supercap was used to keep the power consistent if the rider was to stop at a traffic light (for example). Dynamos can be brought in AC or DC versions I thought. ~Name101

[Codemaster1]

Is it possible to hook the supercapacitor to the ultracapacitor so you can have a fast charge to the capacitor time as well as a constant charge in the ultracapacitor?

[seabeepirate]

Have you considered hand winding coils to be attached to the bike frame on either side of the wheel, and placing permanent magnets on the spokes? It may be possible to turn the wheel itself into the generator, this would be cheaper than buying an expensive motor. I've been researching alternate energy sources and a similar method is used in DIY wind turbines, though usually on a larger scale. It would be similar in design to the cheap bicycle speedometers that you can purchase at your local "mart" store. This would probably help to streamline the generator itself and reduce moving parts to practically zero. Imagine instead of the motor attached to the bicycle frame, only a small capsule containing the coil was attached to the frame. Check out DIY wind turbines for more information on winding your own coils, and possibly for your charge controller.

[thegreatnerd]

Seabeepirate, I was actually considering your idea when I searched for this instructable. I have a feeling someone could definitely change the frame into a Faraday-cage-like circuit and lead it through the tubing rather than on the outside. If so, this could be an awesome idea.

[Kagetsuki]

I don't mean to be critical, but this instructable feels like a web adaptation of a high school science fair project. On top of that the cost of your design reduces the practicality greatly. The motor alone is worth well more than any bike I've ever owned. You could reduce the cost of the system by adapting an existing dynamo system. For instance the dynamos featured just a bit down on this page: http://www.cycle-yoshida.com/parts/light_menu.htm . A 6V 2.4W dynamo specifically designed and shaped for power generation from friction off of a bike tire rim for JPY1080 (less than US$10) should just suffice. And if it didn't modifications to your circuit should.

The circuit here also concerns me. Supercaps are great, but they have low voltage tolerances. To make up for this you regulate the voltage coming in. That basically jips you of a lot of the power coming off of that great motor which brings up a lot of questions regarding your design choices. Perhaps going with a big fat electrolytic capacitor and a dc-dc power IC would allow you to make better use of more of the power coming off that motor.

I understand this comment isn't necessarily a positive one, I do feel it is constructive. Good engineering comes from the realization of bad engineering. Flaunting bad engineering and furthermore using it to promote yourself, as you seem to be doing here, offends me.

[erckgillis]

Yes...thank you a EE geek...

[Kagetsuki]

I believe you intended to use "an" rather than "a" in that sentence. And as English text has no inherent expression of tone I'm completely incapable of determining if you are being sarcastic or genuine. The use of trailing periods implies sarcasm to me, in which case I question why you would rather not have someone with specialized technical knowledge criticize a poor design with a self-serving presentation. If however you were genuine with your statement, then my response is "no problem!".

[jimmy5k]

sounds like someone has a stick up his/her(?) bum. i think this is a great instructable. bit too expensive for my pocket, but none the less, instructive. if kagetsuki wants to shine some light on those less fortunate of his/her great knowledge, feel free to remake this with your mods and post your own instructable so that we may benefit, o great one.

[Kagetsuki]

I described how you could do this for under $20 in the post at the top of this page. 1. Get a proper bike dynamo (just take the bulb out of a bike lamp or spend some money on a hub dynamo). 2. Hook dynamo up in parallel to a fairly high tolerance capacitor. 3. Add a voltage regulator after the capacitor. 4. Add a larger capacity (but lower tolerance) capacitor on the output side of the voltage regulator. 5. Hook up to IPod If you are ever displeased with the performance get more capcitors to place between the dynamo and regulator. Depending on how the iPod handles variable voltages and brownout conditions you may need a bunch of capacitors if you are making frequent stops. I'd write my own instructable for this, but I own neither a bike nor iPod. The fact that this can be replicated and very likely out-performed by a blatantly simple system less than 10% of the cost does in fact irritate me. Using the last page of the instructable as some sort of personal PR irritates me as well. The fact that anyone would want to replicate this without knowing they would be using a blatantly over-expensive solution and relatively inefficient solution depresses me.

[JeffB]

Kagetsuki, Your presence in this Instructable has deteriorated rapidly. I appreciated your constructive criticism, but your continued attacks will not be tolerated. You claim to be against personal PR, yet you do nothing but promote yourself. I have stated multiple times that this system was built as a concept and under a timeline by high school students with no background experience, get off your high horse of "specialized technical knowledge," no one else appreciates it. If you don't feel like making an Instructable, you don't have to mention it. I don't own an iPod either and I probably won't remake this system. You act as if I care about what irritates you, I don't. But if you're curious, your constant attacks on this Instructable irritate me to no end. Sincerely, Jeff

[Kagetsuki]

I'm sorry I've offended you so much. In the future I will refrain from such direct criticisms of your work, and will no longer comment on your instructable. I hope that some day you may understand the point of view through which I made the above comments and look back on this and forgive me. Thank you, and sorry.

[smeeves]

so...... with kagetsukis "suggestions" have you found a cheaper way?? this seems like a great idea!! i also like seebee pirates idea of turning the wheel itself into a generator. (i was actually going to do that in metal shop, make a battery system rechargeable by bike :D)

[JeffB]

You should realize that I wasn't offended by your technical criticism, it was your attitude.