John, sorry for the late answer. Unwanted induction heating on rings necklaces etc: they say it doesn't happen because you need very fine tuning to receive (see the TED video I linked to, the guy walks happily through the power beam, same thing for the original MIT research team photographed while sitting in the beam, photo shown in the video)
Turning witricity off when not loaded: yes, good idea if they haven't thought of that already. If absence of loading can't be detected easily it might be done by communicating via bluetooth or wifi, e.g.: "hi there can you send so many watts my way", the emitter would then deliver witricity until the receiving device stops responding to "do you still need power" enquiries. But anyway that's the idea I gather, your cellphone, PDA or tablet will be charged while in your pocket, which will extend (by at least a factor of two I would guess) its battery life, which would mean a global saving in energy. It makes sense to me. What I would disagree with would be using witricity for TVs and other stuff which could be powered by wire, which I am afraid is in the pipes... Top posting: I do it whenever I think of it if it's not excessively unpractical. Michel 2009/9/16 John Fields <[email protected]>: > On Wed, 16 Sep 2009 10:25:27 +0200, you wrote: > >>Indeed cell phone batteries will still be needed, but with >>sufficiently ubiquitous witricity they will live much longer because >>they will be more or less permanently on charge, even when in your >>pocket: > > --- > For that to happen, the cell phone would have to be in an undulating > magnetic field with sufficient intensity to charge the battery while > quite far away from the source of the field. > > To me, that doesn't seem like a realistic scenario in that metallic > objects close to the source (rings, necklaces,etc) could act like > cookware on an induction heating cooktop. > --- > >>this lengthens considerably a cell phone's life, as it lowers >>the number of cycles in a given period. This is of particular interest >>for newer cell phones, which are used for many other purposes than >>phoning and therefore use more energy. >> >>If the battery lives say twice longer, then the total cost of your >>cell phone's energy is divided by about two (the cost of the >>electricity itself being negligible compared to that of the battery >>wear out). So witricity will save you money, and will probably save >>energy globally, as manufacturing batteries takes energy. > > --- > What you've forgotten about is the fact that induction charging is less > efficient than conventional switch-mode chargers and, unless turned off > when not loaded, will continue to dissipate power. > > On a global scale this would amount to a huge waste of power. > --- > >>Michel >> >>P.S. The top posting convention is a disability thing like Terry said. >>It has been adopted by most email software providers to make life >>easier for blind people. Since they use text to speech software to >>read their emails, with bottom posting thay have to hear all the old >>stuff they have already heard before getting to the new stuff. > > --- > Looking through your older posts here, I notice that nearly all of them > are bottom-posts, yet you chose to top post this one. > > Any particular reason? > >
