The efficiency I was referring to was for a pair of untuned loops loosely coupled, but even at 50% for a more closely coupled resonant system, half the power out of the transmitter would be lost before it got to the load.
And, no matter how efficient the system can be made to be, it can never be made more efficient than the direct ohmic contact made between a plug and a socket. I doubt whether the impact on batteries will even be noticeable, since devices designed to be mobile will still need to be powered by batteries when they're not in the vicinity of a transmitter, the only "advantage" being that their batteries can be charged without having to directly connect a charger to the device. As far as electric vehicles goes, I think the idea of a non-plug-in charger is pure insanity. Why? Arbitrarily pulling some numbers out of thin air, if we assume that the battery needs to be charged from a 120 volt source at 20 amperes for 8 hours, that's 19.2 kilowatt-hours, and at US$0.15 per kilowatt-hour, that's $1.92. Not bad... but, with a non-plug-in charger running at 50%, that's $1.92 thrown away for every $1.92 used. Worse is the fact that it's not just money being thrown away, it's resources being squandered because of laziness. On Tue, 15 Sep 2009 11:28:26 +0200, you wrote: >A more informative video on the subject of witricity here: > >http://www.ted.com/talks/eric_giler_demos_wireless_electricity.html > >Transfer efficiency is not 5% like John suggested but more like 50% >and growing. I suspect the energy loss compared to traditional >solutions will be globally more than made up by the savings in >disposable batteries or rechargeable battery cycles in many nomadic >battery powered applications such as hearing aids and cell phones. > >Not sure about electric cars though, unless the efficiency can be >significantly improved, which I guess can be done by bringing the >coils closer together (either the coil in the car or that in the floor >could be mobile and automatically brought into close proximity of the >other one before charging begins). > >Michel > >2009/9/15 OrionWorks - Steven Vincent Johnson <[email protected]>: >>> From: John Fields >>> >>> On Mon, 14 Sep 2009 16:11:48 -0400, you wrote: >>> >>> >As John Fields says, this is a harebrained scheme. >>> > >>> >My guess is that if the power is high enough to useful work, they >>> >will eventually discover it can harm your health. >>> > >>> >I suppose there are some narrow applications that would benefit from >>> >this technology. >>> >>> --- >>> You're right; there are. >>> >>> One of them is battery powered toothbrushes with resting stations that >>> allow recharge of the cells, in the toothbrush, between brushings >>> without the need for ohmic contacts between the load and the source. >> >> I suspect medical implants, like pacemakers would benefit as well. I believe >> they are working on this. >> >> Regards, >> Steven Vincent Johnson >> www.OrionWorks.com >> www.zazzle.com/orionworks >> >> >>
