USB Bike Generator

Step 5 Final Results

Before I did the final assembly of everything I tested the performance of the new stepper motor, diodes and switching regulator.  I used a dead 5V 1000maH battery as a load and measured the current and voltage input and output of the regulator.  I used the drill press again to turn the generator at its 5 different speeds. The results are listed below.

RPM                           620     1100      1720     2340     3100
Vin (volt)                    5.81      6.61       7.15      7.43       7.67
Ain                              0.15      0.26       0.34      0.38      0.40
Vout                            3.70      4.21       4.55      4.78      5.05
Aout (Amp)                0.15      0.28       0.37      0.42      0.44
Input Power (W)       0.87      1.72       2.43      2.82     3.07
Output Power (W)    0.56      1.18       1.68      2.01     2.22
Efficiency                   64%       69%      69%      71%     72%

As you can see the regulator is right at 70% efficient between 1100 and 3100 rpm.  Also it generated enough power for the USB ports even at 620 rpm.  I also increased the size of the wheel mounted to the generator to slow it down compared to the old BikeGen stepper motor. 

All of the work comes to this final point. The USB Bike Generator can power two USB ports as you ride your bike, to charge your electronics.  The electronics of the system are 70% efficient above 12 mph bike speed and can generate adequate power at 7 mph.  I have tested a rechargeable battery, handheld GPS and an Eton radio with the USB Bike Generator and they all work.  I have also tested a Ipod touch 3gen and have found its is possible to charge but because of the variability of the power source and the pickyness of the Ipod its not very reliable.

I welcome all comments, questions, and suggestions. Thanks 

Comments

[texasclodhopper]

(removed by author or community request)

[roland985]

When I go for rides, I spend roughly 30 minutes each way, 1 hour. Enough to give my smartphone a full battery. I have bought a commercial version of this.

But yes, storage is desirable, make your version with storage.

[pteranosaur]

Clod Hopper-More research,you need MORE RESEARCH...lol

[watermelonhead]

Actually, in the second rebuild of this project, he did just that... instead of directly powering the headlights, it recharged its batteries. He also says that this is not to power, but "The USB Bike Generator can power two USB ports as you ride your bike, to charge your electronics."

[traeblain]

Last question...but why did you choose to abandon the intermediate battery approach you used on your previous generation? I would think the battery could take the flaky charge gracefully, then you'd have clean output power to your devices and would correct for issue with the ipod charging reliability?

[dbc1218]

I think a battery could be used but I would want something to protect it and whatever device I'm using. I wouldn't want to over charge it or drain it to low. That would require another circuit to control everything, which I might try in the future.

[brickbreaker]

Well obviously more research is required before you start building a battery addon for this build but I would like to point out (if its not too obvious) that modern devices with lithium batteries have a set up that prevents over charging. Maybe hacking an old device to be your bike-battery would be easier than building your own circuit? Just a thought.

[lahtib]

Have you considered the use of a capacitor? It might provide some stability while removing the concerns of a battery charge?