Comments on: WiFi Hotspot Power Harvester http://www.greenecomputing.com/2010/01/11/wifi-hotspot-power-harvester/ Android News and Apps Thu, 20 Jan 2011 02:39:19 +0000 http://wordpress.org/?v=2.9 hourly 1 By: Nacoma http://www.greenecomputing.com/2010/01/11/wifi-hotspot-power-harvester/comment-page-1/#comment-8 Nacoma Fri, 05 Feb 2010 00:44:15 +0000 http://www.greenecomputing.com/?p=86#comment-8 BoingBoing (http://boingboing.net/2010/01/12/rcas-wifi-power-harv.html) had an interesting article questioning whether it is a hoax product: "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. " BoingBoing (http://boingboing.net/2010/01/12/rcas-wifi-power-harv.html)
had an interesting article questioning whether it is a hoax product: “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.
“

]]> By: Hoax or confusion. http://www.greenecomputing.com/2010/01/11/wifi-hotspot-power-harvester/comment-page-1/#comment-2 Hoax or confusion. Thu, 21 Jan 2010 18:34:58 +0000 http://www.greenecomputing.com/?p=86#comment-2 There's nowhere close enough energy that passes through that widget to charge a battery. Even if it totally enclosed an access point, managed a 100% conversion rate, and had a perfect battery.... still not even close. There’s nowhere close enough energy that passes through that widget to charge a battery. Even if it totally enclosed an access point, managed a 100% conversion rate, and had a perfect battery…. still not even close.

]]>