Originally published at: http://boingboing.net/2017/07/28/this-solar-powered-battery-can.html
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Ten bucks cheaper on Amazon. C’mon, Boing Boing, are you unaware people have access to Google…?
https://www.amazon.com/26800mAh-ZeroLemon-SolarJuice-Multi-functional-Flashlight/dp/B00NIOGKL8
That solar panel might generate one watt if you are lucky. At five volts that’s 200mA so it will take over 130 hours of sunshine to charge.
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Even at that rate, a day in the sun will be plenty to charge most smartphones to the gills (2500-3000 MAh). And many newer panels are far more efficient than you may realize; I’d guess it’s close to 3-4 watts, considering the size of this 10w panel:
https://www.amazon.com/ECEEN-10Watts-Charger-Samsung-Smartphones/dp/B01BBCVIAQ/
Boing Boing gets a referral bonus, by the by, if you click the auto-expanded Amazon links, so don’t feel TOO bad for 'em =) .
The device is about 0.01 m^2. Insolation at the equator is about 1 kW. m^-2. To get 4 W you would need ideal orientation, weather, location, and the latest in laboratory prototype cells using exotic materials. As no information is given about the cell I suspect it to be a fairly ordinary one with less than 20% efficiency.
With it hanging on a clip as shown I’d be surprised if it gave better than half the theoretical possible output. My estimate was already being generous to the device.
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The Amazon reviewers like it as a battery that they charge at home, but say the solar panel is a novelty. “I placed the device completely drained for a full day, sunrise to sunset under the Arizona sun. That night I was able to add about 20% battery to my phone. This means to get a full phone charge it would take 5+ days of solar energy.”
And it’s nonsense to say this charges “over high-speed USB 3.0”. USB 3.0 is about data speeds. The product claim is “Type-C/USB-C/QC 3.0”, referring to QuickCharge 3.0.
I was with you until this bit. It’s not nonsense to call that USB3. It’s parlance.
Everyone is being sort of a Debby Downer on the solar capacity. It should be pretty clear to everyone by now that nobody is going to be able to use tiny solar panels (with modern consumer technology) to charge their devices for normal use. But I am thinking of this as an emergency device. Assuming it is reasonably waterproof, You could keep it on a pack or saddle to keep itself topped up in case it is needed. It would be somewhat pointless in a mechanically sound car or motorcycle, but in the unpowered wilderness, it could be super helpful. Even if it took hours to get a usable charge. Personally, I like the approach used in Alien Covenant:
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