USB Bike Charger

  Submitted by alex on Fri, 07/18/2008 - 17:41
bike charger
program: 
City Lab

The target is creating a modular powersupply that can be attached to bicycles. The power supply generaties power while you are biking which consequentely is stored or used immediately to charge your cellphone, PDA, MP3-player or a similar device.

A disk, the size of a CD, holding 4 large coper coils, is attached to the front fork of the bike and is hold in place by velcro. On the spokes next to the coil, 4 or 8 magnets are strapped, which pass the coils with every revulsion of the wheel. Using the principle of the ‘permanent magnet alternator’, this produces a current flow through the coils. The current thus generated is altered by a small circuit board under the saddle to fit the output criteria and subsequentely stored by capacitors.

The system will be build to generate 12 volts output, with the possibility to change the output voltage to whatever voltage needed. This allows for different apparatus to be charged.

Project Blog

USB Bike Charger

project: 
USB Bike Charger
program: 
City Lab
Fablab Location: 
MIT Fablab Norway

 

impression scale 1:1 (4 magnets on spokes, 4 coils on a disk)

A MultiPurpose Modulair system

The system will be designed to fit everything with wheels;

ConstructION

2 acrylic disks, the size of a standard CD, will be cut out using a laser cutter, and will hold the copper coils in place. Once attached, the disk will be completely waterproof.

EXTENDED POSSIBILITIES

The system can be mounted on one side of the wheel only, but can, if desired, be extended to include up to four pieces, two for each wheel.

RESEARCH ISSUES

- How to attach the magnets to the spokes

- How to convert the output voltage using a small device.

- How to keep the whole systeem waterproof

- How to do all this in an enviromentaly friendly way

First prototyp:

We used 3mm acrylic plates to put together our first version of the usb bike charger. With a drill machine, Jean michel made the 4 coils, fitting the holes he lasered into the acrylic discs

Here's the disc with 3 coils in it ready to connect.

I made the other disk holding 8 magnets, so we have as much atractions as possible per turn:

Ok, the magnets fitted wel. I made the holes 0.3mm smaller than the magnets. Actually later we added 2 magnets per magnet to increase the power, and also to decrease the distance to the coil disk. It's very important that the magnets are as close as possible to the coils.

Ok, ready to go, mounted on the bike. Looks serious does it :)

Jean Michel attached a led to the coils, and we hooked up the output to the osciloscop to see exactly whats going on.

Result:

We have noticed that its not going to work like that. We need stronger magnets, and more windings on the coils, or even more coils. But we learned a lot how we can optimize the whole thing. We have now thought bout 3 other versions, so stay tuned, we update soon.

The USB Charger Bike Team

 

Jean Michel, Johann Wood & Alex Schaub