Hacker News Reader

Comment by IanCal | Hacker News Reader

The claim on their wiki page was a light bulb at 90% efficiency at 3 feet. If it's more efficient when closer, you could put one in the bottom of your car and one just below the surface of your garage, and you'd probably only have a separation of about 1 foot.

> But the article also talks about lighting and televisions, and cars. WiTricity has investors to fluff, clearly, but is this not absolute crazy talk?

They've apparently already powered lighting, and the TED talk supposedly had them powering a TV [0]

[0] http://www.ted.com/talks/eric_giler_demos_wireless_electrici...

View on HN

From what I've seen of their demos (going off memory), they focus on power transfer to a single device. Their efficiency drops to near 0% when multiple devices are being powered.

I have a hard time getting excited about these guys' work, but will readily admit they are excellent about generating publicity. There is a lot of _very_ closely related work in resonant energy transfer and use of time reversal or lensing currently being looked at around academia. Hopefully one day it will pan out, but it is never going to be as efficient as running a wire. For some applications wireless power is a great enabling technology, but powering a light or a tv in your home? That's a hard sell for the "convenience" of moving your tv versus the extra costs in energy inefficiency.

Ok, sure. If you can control the proximity carefully, you can achieve reasonable efficiency. Transformers work.

But it's still a super high powered magnet. There are more places than not where that's just a bad idea. Garages are high on that list. Also carports, kitchens, living spaces in general...offices, sleeping spaces..bathrooms. All bad.

LED lighting gets you pretty far down the current draw curve, but I don't see a small, easily moved coil generating enough resonant current to be useful in many common consumer electronics. That coil has to be plugged in to the mains, remember -- invalidating the promise of wireless power, even at three feet.

And ambient charging has all of those problems, squared.

Also, can't magnets interfere with pacemakers? "Oh, you have a pacemaker? Ya, don't come over or you will die... I don't want to have to plug in my lamps."

Reply on news.ycombinator.com