
Experts Still Think UBeam’s Through-The-Air Charging Tech Is Unlikely - apsec112
http://spectrum.ieee.org/consumer-electronics/portable-devices/experts-still-think-ubeamrsquos-throughtheair-charging-tech-is-unlikely
======
TeMPOraL
Well, either it works or it doesn't. What's there to talk about? It's not that
they're doing rocket science.

> _" But even amid a tidal wave of publicity, the company has never publicly
> demonstrated a fully functioning prototype of its system."_

This is what I don't get - how the hell did they manage to get investors? I
mean, ultrasound charging isn't magic, anyone who knows their stuff around EE
should be able to throw together in a month a simple prototype of the tech to
show to the investors. That is, a prototype that actually charges a phone, not
this[0] which a) doesn't really charge the phone, and b) seems to be geared
towards confusing people clueless about electricity. The fact that they
didn't, after 4 years, produce anything suggests that they don't even have
anyone on board who knows this stuff, so why are they getting money?

Seriously, I think I'm gonna plug my IRC bot to TTS and go raise money for my
AGI startup.

[0] -
[https://www.youtube.com/watch?v=RoHxyweJcZI](https://www.youtube.com/watch?v=RoHxyweJcZI)

~~~
ykl
Wait, why is she using a volt meter in that video? That's not useful
information without knowing how many amps the system can push. I could
probably get a volt meter to read 8 volts just from my hair after walking on
carpet a bit, but that's certainly not going to charge my phone...

~~~
cnvogel
More specifically, THIS voltmeter, which is a little bit "under-spec'ed", to
say the least: Radio Shack (22-223) [https://www.google.de/search?q=radio-
shack+22-223&tbm=isch](https://www.google.de/search?q=radio-
shack+22-223&tbm=isch) It's set to the 10V-AC range. I'd expect a VC backed
company to invest in a little more elaborate measurement equipment than that.

On the other hand, given a a good RMS meter operated in a frequency range
where it's spec'ed to work and a _known_ _circuit_ _impedance_ will give you a
very good measurement of the power: P=Vrms²/R. And analog meters make for
rather pretty demos, to be honest.

~~~
jacquesm
Actually, that makes it more believable, not less. Let me explain why: A
voltmeter can't just measure volts, it has to make a tiny current flow through
a resistor. The value of that resistor will be lower for cheaper volt meters
because the cheaper volt meters need more energy extracted from the circuit
under test to function. A more expensive one has a very high internal
resistance, and so loads the circuit under test far less.

In this case being able to supply 8 volts into a meter with a low internal
resistance is actually a plus ;)

That said, the current is still tiny, even a crappy volt meter will pull no
more than a few hundred micro-amps from the circuit that it is measuring. So
let's be generous and say that it pulls a whopping 10 mA (very likely on the
high side (edit: it turned out to be 37 uA)), in that case the power generated
would be 0.08 W. Not enough to charge your phone by a long shot, but enough
for a pretty demo with a moving needle.

Finally, these cheap meters tend to output complete nonsense values when
presented with high frequency AC, one would expect that they would at a
minimum measure power transfered using a dummy load and some kind of dedicated
power meter.

All in all this does not make things look any better for uBeam. I'd _really_
like to know who did their technical due diligence.

What's really bad to me - but I'm a nitpicker - is that in the video the lady
refers to the _volt_ meter as a _power_ meter, which it definitely is not. It
measures _potential_ , not power, any power that it takes from the circuit can
be chalked up to imperfect design and the laws of physics. Maybe the person
doing the demo was not knowledgeable about the physics behind the equipment
but that's betraying a complete mis-understanding of the basic concepts
involved.

The transducers used appear to be of the piezo-electric type, those have a
fairly high internal resistance and the voltages produced by those devices
would be relatively high, the currents correspondingly tiny.

What gets me about this whole saga is that uBeam makes it seem as if they
invented wireless power transfer using ultra-sonics, but _any_ sound is
wireless power transfer and that includes ultra-sound. The whole crux is _how
much_ power can be generated and whether or not there is a practical way to
overcome all the obstacles.

To transfer some power doesn't prove a thing, when I whisper in your ear I'm
transferring power using soundwaves...

~~~
cnvogel
As I had remarked, a good RMS meter on a known impedance, on a frequency it's
spec'ed for. The setup shown is neither.

Also: For low-level AC measurements you invariably need active rectification.
So your meter will never be directly connected (or through a series resistor)
to the source.

~~~
jacquesm
Agreed.

The guts of that meter register 37uA for full scale (I found some specs), at
10V that's an internal resistance of 270K so probably it really is driving the
meter directly.

For 8 V that translates into 0.25 mW of power produced, which I don't think
will be charging any cell-phones.

------
hanniabu
"But even amid a tidal wave of publicity, the company has never publicly
demonstrated a fully functioning prototype of its system. Nor has it ever
produced an outside expert (who wasn’t an investor) who could attest to its
ability"

Sounds a lot like Theranos

------
jonkiddy
Reminds me of an old April Fools joke from ThinkGeek:
[https://www.thinkgeek.com/stuff/41/wec.shtml](https://www.thinkgeek.com/stuff/41/wec.shtml)

~~~
jacquesm
That's a good one.

I once lit a large fluorescent tube on the field generated by the antenna of a
fairly powerful transmitter so that joke has some basis in physics. But you'd
be hard pressed to run your vacuum cleaner that way :)

I wonder how many people clicked 'order'.

~~~
toomuchtodo
Standing under high tension power lines will also light up a fluorescent tube!

------
arbitrage314
Many weekends ago, I did a bunch of research on UBeam as I had an opportunity
to invest.

I hope I'm wrong (because wireless power would be cool), but after ~5-10 hours
of research, I think wireless charging is unlikely to happen at any scale that
would make UBeam a good investment.

The amount of sound power required to charge even small electronic devices is
enormous relative to the volume of the sounds we hear every day. Therefore,
charging must occur at a pretty high frequency that we can't hear. Power
efficiency begins to drop at these high frequencies, however, and sound at
these frequencies might have other unintended consequences beyond human
hearing. Power transmission efficiency is low pretty much regardless.

The only way for UBeam to work, I think, is for people to think it's so cool
to wirelessly charge things that they'll pay a lot of money to try it out.
"Killing the power cord" on any sort of larger scale seems very unlikely.

~~~
jasonlaramburu
Do they have a working prototype to show investors? It seems like anything
would go a long way to silence critics at this point.

~~~
arbitrage314
I've seen, with my own eyes, working prototypes deliver amperage. That's
pretty easy, though--just crank resistance down to 0, and you can get as many
amps as you want.

------
olalonde
Related:
[https://news.ycombinator.com/item?id=10527061](https://news.ycombinator.com/item?id=10527061)
(UBeam Declassifies Secrets to Try to Prove Wireless Power Is Possible)

------
raverbashing
Even if it works perfectly, from the other article they had, pointing that
they can get ~ 3W at a device (and their transmitter is how much, around 300W
as well) should be enough to cast a lot of doubts

------
brokentone
These are the concerns that I have had since I first heard about this product.
It's really simple physics... the falloff here is far too great. Come on,
efficiency people!

------
v3ss0n
How about tesla coils?

~~~
jacquesm
How about them? Do you mean: Can an electric field of sufficient strength be
used to charge cellphones?

~~~
kwhitefoot
Nokia had a project to charge mobile phones from ambient radio waves. But they
had real engineers and scientists and even though it actually worked they
reported how badly it worked. That is, the charging rate was so low that only
the simplest mobile could be charged with it. I think they used a modified
Nokia 100 or something similar. See this 'article' on Gizmodo:
[http://gizmodo.com/5285565/nokia-developing-wireless-
accesso...](http://gizmodo.com/5285565/nokia-developing-wireless-accessory-
free-ambient-charging)

------
IshKebab
You don't need to be an expert to see that.

