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Potenco's Latest Pull-Cord Power Generator - Wired Video Answered

Check out Potenco's latest pull-cord generator in this interview Colin did for Wired.

Video: Potenco's Latest Pull-Cord Power Generator

A couple of weeks ago, we headed out to Potenco's amazing headquarters at the decommissioned Alameda Naval Base to check out their power generator for the developing world.

It looks a bit like a yo-yo, and generates an average of 25 watts of power in normal operation. That's enough to power twenty minutes of cellphone talk time with just one minute of pulling.

Their engineering feats could ultimately enable millions in the developing world to access information through their cellphones and internet devices, and light their homes with smoke-free lanterns. Now all they have to do is get them out into the field.

One proprietary thing we couldn't show you was the Potenco cord testing room, where a Rube-Goldberg looking machine put dozens of types of strings through thousands of simulated yanks and pulls.

Nicholson Baker envisioned such a machine in his book, The Mezzanine, but for shoelaces, not power generators. We echo his thoughts on the relationship between finding the right strings and civilization's advance: "He had constructed a machine and strapped hundreds of shoelaces of all kinds into it, wearing them down over and over, in a passionate effort to get some subtler idea of the forces at work... Progress was being made. Someone was looking into the problem."

Enjoy the video! Thanks to Potenco (especially Mike Lin and Colin Bulthaup) for letting us come out and Michael Lennon and Annaliza Savage here at Wired for putting it together.


Ok, I see where this can be made simpler and more durable than any crank system, but I am still wondering about efficiency. I don't want to second guess anyone but what I had always envisioned was a fold up crank handle (unfolded gives twice the leverage and the ability for continuous movement rather then stop start), and a small simple centrifugal force activated flywheel system that would start out easy to pull, and remain easy, but would create more and more torque as the speed of the innards increased.

From what I recall/guess, you probably couldn't do that w/ gears anyway. The attraction from the magnets would be too strong, and it would stop too quickly after for it to be useful.

Well, I wasn't really thinking gears, but I do see what you mean, even with the set up I was imagining ( as the speed was ramped up, the centrifugal force would "widen" the spinning mass and create a "flywheel effect") it would probably have the same problems you mention. I might still give it a go if I can find the right kind of mechanism to test. :-)

Have you seen the machines in gyms that are like cycling with your arms, a crank like that would allow a much larger output than wrists while eliminating the need for push-pull motions, or a free moving handle on a ball joint allowing yoou to spin using your wrist of whole arm giving a greater energy output over time as there's less complete resting needed.

Yes, this and a few other (smaller) devices I have seen over the years are getting my head to "spark" again :-) When I have a lot of ideas flying around, it is like spark plugs firing, so I refer to it as "sparking".

I always felt it to be more like the little bits of flint from a lighter flying around and igniting, also sparking...

Well, they said they didn't use any gears. I imagine w/ interesting transmissions, you could get around it.

so many things going through my head at the moment...I have to go jot down things before they vanish...BRB.

. That is addressed in the video. Evidently, arms are more efficient at making long strokes.

Agreed, but each stroke starts and stops, whereas a circular motion does not need to stop, reverse direction, and start all over again. This was the principle behind the Wankel engine, eliminating the piston's starts and stops.


. I dunno, Just going by what they said in the movie. It does seem to me that a constant, regular motion would be better, but what do we know? :P

Well, I do want to see if I can find something that would be even remotely like what I have dreamed up just for a test run for my own satisfaction. :-)

. I don't see why you couldn't use a separate crank to drive the thing if you use a loop of string or narrow belt. Wouldn't be exactly the same, but close.
. A crank seems to me to be a much more appropriate choice if you need a steady output, but they are only wanting to charge batteries. And a crank mechanism adds to manufacturing/maintenance costs.
. I'll guess that the "extra" power you get from using extended arms (leverage + longer draw) makes the average power output greater than what one can get from forearm/wrist movements.

. I'll guess that the "extra" power you get from using extended arms (leverage + longer draw) makes the average power output greater than what one can get from forearm/wrist movements.

Yes, which is why I was thinking of a way to increase the "output" with the speed of being cranked. I can increase the leverage a bit with a fold out crank (I have an old 100 ft measuring tape that cranks in this way), and if a mechanism that increased the output ratio as speed increased, I could possibly overcome the downfalls of the crank, except one......the maintenance would probably be greater, as you mention. Still, it might be fun to try it...