[ausev] wireless charging

[Clendon Gibson]

I have been confused by this technology. It seems like with all the interest in environmentally friendly, energy efficient solutions that this wireless charging would be a non starter. 

Can the magnetic resonant version ever be as energy efficient as a wire cable?



----- Original Message ----
From: Marc Kohler <mkohler at austin.rr.com>
To: AustinEV News Announcements and General Discussion <ausev at austinev.org>
Sent: Wednesday, January 21, 2009 8:19:14 AM
Subject: Re: [ausev] wireless charging

Gil, that's why I mentioned the magnetic resonance version.
It travels much farther than inductance and can only be "felt" when you have
a matching receiver tuned to that resonant frequency.
Marc

-----Original Message-----
From: ausev-bounces at austinev.org [mailto:ausev-bounces at austinev.org] On
Behalf Of Gil Dawson
Sent: Tuesday, January 20, 2009 6:31 PM
To: AustinEV News Announcements and General Discussion
Subject: Re: [ausev] wireless charging

> It looks like a mouse pad and can send power through the air, over  
> a distance of up to a few inches. A powered coil inside that pad  
> creates a magnetic field, which as Faraday predicted, induces  
> current to flow through a small secondary coil that's built into  
> any portable device, such as a flashlight, a phone, or a  
> BlackBerry. The electrical current that then flows in that  
> secondary coil charges the device's onboard rechargeable battery.  
> (That iPhone in your pocket has yet to be outfitted with this tiny  
> coil, but, as we'll see, a number of companies are about to  
> introduce products that are.)

> We were able to transfer 60 watts with ~40% efficiency over  
> distances in excess of 2 meters.

GM's EV1 and S-10E, and  and Toyota's Rav4EVs all used Inductive  
Coupling to transfer up to 6 kw for charging.  The paddle is held  by  
a slot and springs rather closely to the coils, but there's still  
perhaps 1/4 inch of play, so it is over some bit of distance.

Getting this technology to work over room-sized distances may be  
feasible soon, even within an acceptable efficiency.  But can you  
imagine what it will take to get OSHA to approve people in  the  
workplace walking through a power transfer field?

--Gil
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