On Tue, 15 Sep 2009 10:30:56 -0400, you wrote: >These people claim they can improve over direct connection charging: > >http://www.wipower.com/
--- I have trouble following a long thread once it starts getting snipped and top-posted to so, if you don't mind, I'll continue this one by bottom posting: I couldn't find where they made the claim; do you have a link, please? In any case, since their system is loosely coupled, I doubt whether it would be possible to be more efficient than a tightly coupled system, so their claim may be just that; a claim with no basis in fact. Also, the more I read from them, the more skeptical I get. For instance, on Youtube at: http://www.youtube.com/watch?v=Bz5D5_Jzg-M They claim: "WiPower power 5 light bulbs using inductive coupling @ 74% DC to DC efficiency." Efficiency is usually defined as the ratio of output power to input power, so if they're talking about the input power coming from a DC source, then they've glossed over the losses in the AC to DC conversion process which must take place between the mains and the input of their transmitting device, thereby making their machine look better than it actually is. Another troubling thing is that there's no mention made as to the wattage of the light bulbs or the change of efficiency VS load. As a matter of fact, there's a paucity of technical data on their web site, particularly quiescent operating current which, if high enough, could easily relegate their device to the class of devices which should be unplugged when not in actual use.
