
Router can power your devices wirelessly from 15 feet away - jonbaer
http://www.engadget.com/2015/01/05/energous-wattup-wireless-charging-demo/
======
ohazi
No, it can't. This happens every year, and every year it turns out to be snake
oil.

Anyone remember this?

[http://www.engadget.com/2010/01/09/airnergy-wifi-power-
syste...](http://www.engadget.com/2010/01/09/airnergy-wifi-power-system-gives-
rca-a-reason-to-exist-video/)

~~~
ohazi
Also how are these guys a public company? They're acting like some hotshot new
startup, but they're a public company with nothing to their name but a patent
and the fuzzy goal of licensing this pipe dream to other companies. The
executives seem to have impressive bios, but the only ones that are taking a
salary are the CEO and CTO. They supposedly have 9 employees as of 2014 (there
are 6 non-independent board members, so three engineers?).

It just keeps getting weirder... this is starting to look more like fraud than
your average startup-peddling-snake-oil.

------
jrockway
Are they ignoring the FCC's EIRP maxima (and beamforming penalty) on the
2.4GHz ISM band?

If they aren't, they can still get 1W theoretically, which is actually useful:
it can kind of charge your phone in 8 hours. Assuming 100% of the power is
captured by the antenna, that is. (Note that I say theoretically: the real
world is very bad for theoretical models.)

Also something to worry about: the FCC's maximum permissible radiation
exposure. For 6 minute controlled application (people near the transmitter
know it's on), you're allowed an energy density of 5mW per square centimeter.
An iPhone 4 is about 55 cm^2, so that would mean a maximum of 275mW. That
would charge the phone in 24 hours. (These are guidelines for amateur radio
operators, not Part 15 devices; I don't know what the regs around Part 15 say
about power density. The regs also cover far-field effects, not near-field
effects, so perhaps they can get around these.)

Finally, if you want to play with beamforming and figure out how to get 100%
of the power to a 55 cm^2 area, try:
[http://apenwarr.ca/beamlab/](http://apenwarr.ca/beamlab/)

~~~
andruby
2.4Ghz is only used for the bluetooth communication, not for the power
transfer. That happens at 5.7-5.8Ghz.

"What are the RF spectrums being used by WattUp?" [1]

\- 2.4GHz (Unlicensed) for Bluetooth Low Energy communication

\- 5.7-5.8 GHz (Unlicensed Industrial, Scientific & Medical, ISM) band for
power transfer"

[1] [http://www.energous.com/page-f/](http://www.energous.com/page-f/)

~~~
jrockway
Same EIRP regulations and RF safety regulations for all ISM bands, as far as I
can tell.

(900MHz has a slightly difference RF exposure calculation that you have to do
compared to 1300MHz and up. But 2.4 and 5 are the same.)

------
jacquesm
See also:

[http://www.witricity.com/](http://www.witricity.com/)

On HN:

[https://news.ycombinator.com/item?id=7404884](https://news.ycombinator.com/item?id=7404884)

And this one:

[http://techcrunch.com/2012/07/11/disruptive-defined-ubeam-
la...](http://techcrunch.com/2012/07/11/disruptive-defined-ubeam-
lands-750k-to-let-you-charge-gadgets-without-plugs/)

On HN:

[https://news.ycombinator.com/item?id=4232925](https://news.ycombinator.com/item?id=4232925)

This is a weird bit in the article:

"To demo its tech, Energous has turned a casino suite into a faux home full of
wireless power, which we dropped by to allow the company's founder Michael
Leabman to put on a show for us."

If there is one thing that sets off my spidey sense during due diligence on
new products it is demos in controlled environments.

------
pmontra
The post and the product page at
[http://www.energous.com/overview/](http://www.energous.com/overview/) don't
have much details. However the product pages has some data about the power
output:

> Power Delivered to a Consumer Full-Featured Product

> 4W delivered simultaneously to 4 devices, 0-5 feet

> 2W delivered simultaneously to 4 devices, 5-10 feet

> 1W delivered simultaneously to 4 devices, 10-15 feet

> Delivering on average 2W to 4 devices simultaneously within the charging
> envelope

Things that concern me are, in random order:

\- Is it safe to keep the device (let say it's a phone) in a pocket or close
to one's head while is it charging?

\- Is it safe to sit/sleep for hours in between the charger and a (possibly
somebody's else) device?

\- How focused the power beam is?

\- What are the safety measures to prevent other people stealing the power?
Think about the family living on the other side of the wall. Probably
Bluetooth pairing, but I'm not 100% sure.

\- Does it cause reduction of bandwidth for WiFi? (it uses the same
frequencies)

\- Compliancy with regulations about electromagnetic pollution? They started
the certification process in the USA for a receiver
([http://www.energous.com/energous-completes-initial-fcc-
part-...](http://www.energous.com/energous-completes-initial-fcc-
part-15-certification-testing-wattup-wire-free-charging-receiver/)) but I'm
more worried about the transmitter.

------
davej
Surely this would mean sending very high powered microwaves around a living
space. Does anybody have more information/knowledge about the medium to long
term safety of this approach.

~~~
JetSpiegel
Just don't have any chocolate in your pockets.

------
Mithaldu
They claim to reach 70% efficiency, by transmitting power on the wifi bands,
and compare it to a charging mat (90%), and tout 15 feet distance, but leave
out one detail:

How quickly efficiency drops off.

I suspect you only get 70% if your phone is literally on top of the router,
and that the efficiency drops of very quickly to 0 as you approach the range
limit.

~~~
richardwhiuk
The suspicion is that the 70% efficiency is how much of the power arriving at
the phone can be used for charging it, not much the transmitter is supplying.

~~~
johngd
My car's USB port can barely charge my Samsung Galaxy 5.... I can't imagine
how long it would take via radio wave.

------
plaes
~4.5m for the rest of the world..

------
IanDrake
>but none of the solutions have ever set our devices free from a charging pad,
which is tantamount to plugging them in, really.

No, not really. I love my wireless charging pad it's as easy as putting my
phone down, which I do when I'm not using it anyway.

~~~
collyw
Plugging them in isn't such a big deal.

~~~
toomuchtodo
The port wears out over time. I'd rather use the less efficient wireless
charging rather than have to replace a port on a device at some point in its
life.

~~~
HelloMcFly
In all of the years I've been using electronics I have never had to replace a
port. I'd argue anyone concerned about that is likely an edge case.

~~~
bentcorner
I agree. Engineers have done good work on ensuring cables fail before ports
do.

I've been careless (charging a phone in my pocket) and broke several cables.
The port is still rock solid.

------
gpvos
And if you have your phone in your pocket and happen to be in the beam, your
testicles get microwaved. (Well, I hope and may assume that they addressed
that in some way, but the article doesn't mention it.)

------
Kenji
Please stop it already with the wireless powering. That stuff was discovered
by Tesla ages ago, it's a very well known technology and it has very well
known drawbacks like that the efficiency drops proportionally to distance
square and that these kinds of electromagnetic waves actually do have a
negative impact on human health.

~~~
jrockway
Wireless power has worked fine for a hundred years. Ever use a crystal radio?

Your health effects are very clearly in the [citation needed] area. The only
negative effect from long-wave radiation (not gamma or UV) is that it heats
things. If you heat a human too much, they die.

~~~
Kenji
Ever sat in a microwave while it was running? That is exactly what is
happening to your body if you are between this charging router and a device
that draws a lot of energy. Ever put a lightbulb in a microwave? That is
exactly what will happen in your apartment between this charging router and
the charging device. It's a safety and health hazard and it provides little to
no benefits. And please, that high powered electromagnetic waves are a health
hazard does not need a citation.

~~~
Matumio
But I'd like to know if the power density of this device can get anywhere
close to the "health hazard" limit. We need citation or numbers about that.
I'm sure you can already harvest some microwatts from wifi, and most people
agree that nobody dies because of that.

~~~
Kenji
Of course nobody dies of WiFi. I'm not claiming that WiFi kills you. What we
are talking about here is transmitting multiple Watts (or else your phone
takes forever to charge), or even more, through the air. That's a lot of
orders of magnitude more than microwatts.

~~~
minikites
And microwave ovens are orders of magnitude more than the claimed 1-4 watts,
so stop using that as a scare tactic.

~~~
icebraining
Microwave ovens are isolated. They certainly don't output watts to the
outside.

 _" A Federal standard limits the amount of microwaves that can leak from an
oven throughout its lifetime to 5 milliwatts (mW) of microwave radiation per
square centimeter at approximately 2 inches from the oven surface."_

[http://www.fda.gov/radiation-
emittingproducts/resourcesforyo...](http://www.fda.gov/radiation-
emittingproducts/resourcesforyouradiationemittingproducts/ucm252762.htm)

~~~
jrockway
Microwave ovens are very leaky. A coworker and I walked around our office with
a spectrum analyzer* and turned on microwaves. Much leakage into the upper
2.4GHz wifi band on every one we tested, no matter old or brand new.

* Actually, we were using a Wi-Spy. No need for sensitive lab equipment to detect this much radiation.

