Wireless Charging on the Horizon?

When I travel, I routinely three extra USB cables: The proprietary cable for my cell phone, the proprietary cable for my podplayer, and the proprietary cable for my digital camera.

For the camera and the podplayer, the cables serve for transferring files. For the phone and the podplayer, the cables also charge the batteries (the camera uses AAs). And I know other persons who are tangled in cables that they use primarily for charging the batteries of their USB devices.

Now comes a company called Witricity, which is working on a wireless charging system using, if I remember my high school physics correctly, electromagnetic induction to charge a device without a cable.

The BBC reports (full story here):

    The system uses two coils – one plugged into the mains and the other embedded or attached to the gadget.

    Each coil is carefully engineered with the same resonant frequency. When the main coil is connected to an electricity supply, the magnetic field it produces is resonant with that of with the second coil, allowing “tails” of energy to flow between them.

    As each “cycle” of energy arrives at the second coil, a voltage begins to build up that can be used to charge the gadget.

    Mr Giler said the main coil could be embedded in the “ceiling, in the floor, or underneath your desktop”.

    Devices using the system would automatically begin to charge as soon as they were within range, he said.

I have qualms about this item in particular: “Devices using the system would automatically begin to charge as soon as they were within range.” I know that Lithium-Ion batteries are different from NiCADs, but I would like to see more on whether constantly recharging batteries when they are almost fully charged (which would happen in this automatic scenario) has a deletorious effect on battery longevity.

Follow the link to the story to for more details and a nice little diagram.

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