Rechargable USB Battery Pack + Wind-Up Power

[Zone-5]

What about wind-up power, doesn't need sunshine... very portable.

Eton NBOTU4000S
Eton Rechargable USB Battery Pack with Hand Turbine Power Generator

Give yourself a power boost! BoostTurbine4000 from Eton is a durable back-up battery with a hand turbine power generator that provides power when you need it most. For everyday or emergency use, BoostTurbine4000 enables you to charge your mobile device anytime, anywhere. Fast and efficient, in one minute the hand turbine power generator can produce enough power for about 4 minutes of talk time and a few critical texts. When fully charged, BoostTurbine4000 fully charges most smartphones twice. BoostTurbine4000 is made of tough but lightweight aluminium and with its sleek and elegant design it's compact enough to fit in your pocket. BoostTurbine4000 features a Micro-USB DC input to use with most smartphone chargers and a high output (2.1A) USB port for charging most mobile devices, including tablets. Press button to see LED indicator of battery charge level. BoostTurbine4000 is completely self-contained and it's all you need for an on-the-go-power solution.

* Backup battery pack with rechargeable 4000mAh lithium battery
* Hand turbine power generator
* Lightweight and durable aluminium body
* Fully charges most smartphones twice when fully charged
* USB output to charge smartphone or tablet

http://www.amazon.com/Eton-NBOTU4000B-R ... 475&sr=1-6

[GPSGuided]

Curious as to how long or how many windings would it take to fully charge an iPhone or a AA NiMH cell?

[Mark F]

Like virtually all these sorts of products they don't want to talk about how much cranking is required to charge the battery. From the Amazon link provided:
"Second, I tested the hard charging mode. I drained the battery on my phone and this device. I rigged up an "auto winder" using tools in the garage and set it to crank. I would check the LED panel every few minutes and even after 45 minutes (of cranking)! the LED was on 1. I hooked my phone up and turned on this device. It booted, for a minute, then turned off. The hand cranking did not provide enough power to let me send a text even after all this time cranking. "

[GPSGuided]

Yes, a bit of a con. The only hand cranking generator that seemed to work ok was a hand torch. At least it worked reliably without any hard work.

[icefest]

250 watts is about what the average human can reliably produce for any period of time (and that's on a bicycle).
I guess that you can make maybe 10% if that using your hands.
Divide that by half to account for mechanical inefficiency.
And halve it again for electrical round trip efficiency losses.

That bring it to 250*0.1*0.5*0.5= 6 watts. This is about what I've seen advertised with these crank generators.
You might be able to double that with a good system (eg rowboat string style).

So you might be able to produce as much as ultra slow usb charging.

Give solar another 10-20 years and we'll be good for hiking. When thin film arrives at 40%+ inefficiencies it'll be better than the current batteries (but then batteries will be better too)

[GPSGuided]

250 watts is about what the average human can reliably produce for any period of time (and that's on a bicycle).

Based on experience and known data, sustained 250W would be pretty optimistic for an untrained cyclist. I'd be looking at the 200 and below range. Just a bit of trivia. But guess the important issue is, the device is not even close to being worth its $80 price tag.

[walkerchris77]

Curious as to how long or how many windings would it take to fully charge an iPhone or a AA NiMH cell?

A few months

[Zone-5]

Those Amazon reviews are so funny but true...

"You are not going to use the crank on an airplane. Why? Because you will probably be arrested as a terrorist. They would be justified. Do yourself a favor and just buy yourself a dedicated battery pack. It is smaller, lighter and has a larger capacity."

Hmmm, I guess I'll just stick to windy power then...