I'm having trouble believing that RCA's Airnergy, a "WiFi hotspot power harvester" unveiled at CES, can actually charge its internal battery from WiFi radio signals.
The Airnergy has a battery inside it, so you can just carry it around and as long as you're near some WiFi, it charges itself. Unlike a solar charger, it works at night and you can keep it in your pocket. Of course, proximity to the WiFi source and the number of WiFi sources is important, but at the rate it charges, if you have a home wireless network you could probably just leave anywhere in your house overnight and it would be pretty close to full in the morning.
A commenter on OhGizmo! offers the following:
Here's some math. Long story short, by my calculations, 100% efficiency and absorption at 5 feet away from a 100mW home router, (reasonable figures), it would take 34.5 years to charge that blackberry battery.
It's not a Dyson Sphere, so you only get the power that hits the antenna.
Surface of a sphere = 4pir^2, r = 60" (5 feet).
Surface area of a 5' sphere = 45,216 square inches.
The device appears about 2" x 3" = 6 square inches.
The device then picks up, best case, 0.000133 of the power out from the router, which is 100mW, so.. 0.0133mW
If you leave it there for 24 hours, 0.0318 mWh are stored.
According to Will's battery, it has ~4,000 mWh capacity.
So, it would take 12,579 days, or 34.5 years, to charge your blackberry battery once, presuming 100% absorption, no losses.
(BTW, What is that dent in the gadget about? Looks like someone poked it with an awl.)
RCA Airnergy Charger Harvests Electricity From WiFi Signals
The flashlights in our household have a tendency to wander off. Where do they go? I gave my last remaining one to my daughter for a camping trip, so I just reordered an 8-pack of metal LED flashlights for $14. Each flashlight has 9 LEDs and uses 3 AAA cells (included, though some reviewers on […]
Unlike a multimeter, this battery tester isn’t battery powered. Instead, it measures the voltage across the terminals of 9V, AA, AAA, C, D and 1.5V button type batteries. It’s also easier to use than multimeter probes. It’s only $6.61 on Amazon and has a 4.5 star rating with over 1500 reviews.
This handheld magnifying glass has two bright LEDs and is powered by 3 AAA cells (not included). The manufacturer says the magnification is 40X. I think it is less than that, but it is still plenty powerful for my needs – mainly, reading the markings on tiny electrical components and checking the layer fusion on […]
Watching Netflix, Hulu or other streaming services can unfortunately be difficult while traveling outside the US. Rather than bypass these restrictions with the help of a complex and slow VPN, choose a faster and simpler solution with Getflix. Instead of rerouting all your Internet traffic through a different server, this handy service only routes the […]
Shake, stir, and muddle your way to delicious homemade cocktails with this must-have bar set. Expect only the finest quality tools from MakersKit — enabling you to unleash your inner mixologist.Top 12 Favorite Things of 2014, Sunset MagazineQuart-size vintage-style Mason jar shakerRetro double jigger for accurate measurementsStrainer & spouts for a mixologist-style smooth pourHardwood muddler […]
The Lytro Illum dares to be different, boasting even more robust features than its first generation predecessor and a sleek design reminiscent of professional DSLRs. What’s so cool about it? Most cameras capture the position of light rays, producing a statoc 2D image.