In the EU the maximum legal Wifi transmission power is 100 milliwatts, however, on average 802.11 devices transmit at 50mw. Now in accordance with the inverse square law, at a distance of 5 meters, the power is reduced to 1 \/ (5^2) * 50mw = 2mw. Two milliwatts at 5 meters. Assuming they have a respectable electrodynamic induction efficiency of 75%, they will be able to convert 75% of that 2 milliwatts back into electricity: 1.5 milliwatts.<\/p>\n
It takes 50 times that to power a single LED. This means that if their internal battery is 3 volts, 3000mAh it will take about 5000 hours to charge it to full capacity.<\/p><\/blockquote>\n
So, how long does an iPhone battery(3.7V, 1400mAh) get fully charged from zero?<\/p>\n
\r\nRequired power = 3.7V * 1400mAh = 5.18Wh\r\nSupplied power = 1.5mW = 0.0015W\r\nHour to get fully charged = 5.18 \/0.0015 = 3453.33 hours = 4.72 months\r\n<\/pre>\n4.72 months??!!<\/strong><\/p>\n–Derrick<\/p>\n
<\/p>\n","protected":false},"excerpt":{"rendered":"
Today I read an article about Airnergy, a product developed by RCA to recharge the portable device using Wi-Fi signal. I think the idea is pretty interesting because wireless power(not Continue Reading →<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_hide_featured_image":false,"_jetpack_featured_image_duplicate_dismissed":0,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[94,14,6],"tags":[62,61],"class_list":["post-590","post","type-post","status-publish","format-standard","hentry","category-computer-problems-computer-help-pc-support","category-fun","category-technology","tag-crazy-idea","tag-wi-fi"],"jetpack_publicize_connections":[],"jetpack_shortlink":"https:\/\/wp.me\/p1sqzr-9w","jetpack_sharing_enabled":true,"jetpack-related-posts":[{"id":149,"url":"https:\/\/icesquare.com\/wordpress\/bandwidth-tester-add-on-for-firefox-35\/","url_meta":{"origin":590,"position":0},"title":"Bandwidth Tester Add-on for Firefox 3.5+","author":"Derrick","date":"July 15, 2009","format":false,"excerpt":"I always go hunting the Wi-Fi networking using my laptop. 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