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Original RCA Claim
The Airnergy charger from RCA was supposed to be the next wave in amazing but true technology. The little device claimed to use ambient Wi-Fi waves and convert them to DC energy. The energy was to be stored in an onboard battery until it connected to a desired device.
If this had turned out to be true it would have, hands down, been better than a solar charger as it would have worked wherever Wi-Fi signals were available. These wild claims were challenged at CES 2010 but RCA seemed to back them up with an impromptu demonstration of the device. During a live test, “the Airnergy charged a Blackberry from 30% to full in just over 90 minutes only using power from Wi-Fi signals." Of course, there has not been any further demonstration of the device and when RCA has been asked about it, they claim the project to be “dead."
Several websites who had sent their writers to cover CES 2010 were taken in by the Airnergy with a Gizmodo writer enthusiastically cheering for it until readers on the site made it clear that this device simply defied the laws of physics.
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Revised RCA Air Charger
At CES 2011, RCA debuted their new Air Charger system, which seemed to be a totally rethought (and repackaged) mobile charger. This charger garnered them an innovations honoree status. The new device, produced by Audiovox, is described on the CES Innovation Honoree portable power website as follows, “The RCA Airpower(TM) Charger recycles existing energy from Wi-Fi, artificial light sources and the sun to charge and power mobile devices such as smartphones and other 5V low-power portable devices."
This rebranding of the device with additional solar panels lets RCA still claim to use WiFi ambient energy as one of the chargers power generating (or recovering) methods. There is no marketing in place for this device as of yet and the web presence is minimal at best.
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The massive failure of RCA to fulfill the promise of the Airnergy served as a warning for future innovators not to over-promote technology that is still in the beta stage and to definitely not fabricate tests or test results. At the same time this also showed how eager people are to latch on to “magical" devices in the hopes that they may become real.
Although there may be a place for ambient WiFi signals in the world of technology, it is not in the area of charging. The math simply doesn’t support it. If we were to assume that a WiFi charging device works at 100% efficiency charging it from a 100mW home router then the following would be true -
The charger would have to attain 100% efficiency within a spherical region based on the size of the surface of a sphere based on the size of the device (4pir^2, r = 6"). The area is 452.16" so in the best possible situation the charger would have to be within this 37-foot area to charge. The device is capable of picking up 0.000133 of the power out from the router (based on the 2.4GHz output). This means a charge rate of 0.0133mW. In 24 hours, the device will charge 0.0318mWh. A typical cell phone battery has about a 4,000mWh capacity. At this charge rate, it would take 12,579 days, or 34.5 years, to charge a battery once.
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Image Courtesy of RCA