Power over WiFi

[loneoceans]

There have been a lot of news lately on 'wireless power' lately, many of them related to WiFi as well, and many of which may dubious claims. 

For example, here's one: http://www.wired.com/2015/06/power-over-wi-fi/ I came across today. This worries me because there seems to be a lot of misinformation regarding wireless power these days (mixed in with some real proper research though), and quite a bit of media hype as well. Above, it was claimed to add such capability with a simple 'firmware upgrade'.

I was wondering if Dave would be interested to make an episode both explaining how wireless power could work e.g. via phased arrays, as well as talk about the downsides to such a technology (e.g. inefficiency, added RF noise and power etc), as well as the possible upsides (maybe it'll work for very low power devices which wake up periodically etc).

[Howardlong]

There have been a lot of news lately on 'wireless power' lately, many of them related to WiFi as well, and many of which may dubious claims. 

For example, here's one: http://www.wired.com/2015/06/power-over-wi-fi/ I came across today. This worries me because there seems to be a lot of misinformation regarding wireless power these days (mixed in with some real proper research though), and quite a bit of media hype as well. Above, it was claimed to add such capability with a simple 'firmware upgrade'.

I was wondering if Dave would be interested to make an episode both explaining how wireless power could work e.g. via phased arrays, as well as talk about the downsides to such a technology (e.g. inefficiency, added RF noise and power etc), as well as the possible upsides (maybe it'll work for very low power devices which wake up periodically etc).

It's been covered here to some degree https://www.eevblog.com/forum/crowd-funded-projects/wave-a-cell-phone-that-charges-battery-with-wifi-signal/msg687309/#msg687309

[SL4P]

'We' were all concerned about getting brain cancer from our cellphones and TV remote controls...
Let's get 'really' worried about high-powered RF power distribution within our homes!

[Howardlong]

I totally agree that the bullshitters have taken over the asylum when it comes to power over RF, but even for the few that work it's difficult to see where RF delivery would be better than solar in terms of power for most use cases even indoors given a similar harvesting aperture area.

[tszaboo]

It's a shame bullshitters are ruining the image of wireless power delivery at a distance. For extremely low power devices it is quite practical. You can run an LCD clock/hydro/temperature display from commercial radio and TV broadcasts using a standard set-top antenna. It's niche, certainly, but potentially useful.

No, the real problem is that people confuse wireless charging with energy harvesting.
The Qi chargers work with some 50% efficiency in 5mm distance. And people expect to charge phones and their stupid smartwatch with it. And the IoT is just around the corner.
I think the EU should actually make a law, that things requiring more than (say) 1mW average power are banned if they charge wirelessly.

[tszaboo]

I think the EU should actually make a law, that things requiring more than (say) 1mW average power are banned if they charge wirelessly.

Wireless charging has a couple of big advantages for some devices. It works through plastic, so for waterproof devices like smart watches, wireless headphones and some phones it is ideal. It also cuts down on wear on the USB socket, and makes it easy for businesses like cafes to provide standard chargers that won't get broken by excessive use. I bet the number of devices saved because they were waterproof or the USB socket didn't get trashed is a major environmental win.

Actually the other advantage of wireless charging is that it tends to be slower than wired charging. That means less wear on the battery, so less recycling. It's even better with shit like the iPhone where you can't replace the battery yourself (at least not officially).

Grr. You know I'm talking about wirelessly with energy harvesting, not Qi charging.