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Is RCA's Airnergy Snake Oil?

kdawson posted more than 4 years ago | from the deepness-in-the-sky dept.

Power 271

Ben Newman writes "Of all the tech that's come out of CES this week, nothing has gotten the blogosphere more excited then the RCA Airnergy. A lot of people love the thought of an ever-recharging cell phone, and the Airnergy promises to constantly charge its internal battery through 2.4GHz wireless signals. Neat idea, but as some commenters have pointed out the energy just isn't there to make this work — BOTECs for a full charge range from 100 days to 32 years. Plus, don't let the RCA brand fool you into thinking this must be from a legitimate company: RCA hasn't existed as anything more then a licensed brand name for a couple of decades. So what do Slashdotters think — real deal or 21st century hokum?"

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Yeah, tens of meters from a 50mW power source... (5, Insightful)

francium de neobie (590783) | more than 4 years ago | (#30747934)

Is totally gonna charge up your battery and run your cell phone for days.

The inverse square law and dBm being a logarithmic unit can all go to hell.

Re:Yeah, tens of meters from a 50mW power source.. (2, Informative)

WarJolt (990309) | more than 4 years ago | (#30747964)

the mythbusters tried to get power from the em radiation from a high voltage line. That doesn't work nothing will.

Re:Yeah, tens of meters from a 50mW power source.. (4, Informative)

TheKidWho (705796) | more than 4 years ago | (#30747984)

Not necessarily, frequency is just as important as voltage and current.

Re:Yeah, tens of meters from a 50mW power source.. (4, Informative)

MichaelSmith (789609) | more than 4 years ago | (#30748040)

Yes. Solar power from visual light (EM radiation) works very well. We know that.

Re:Yeah, tens of meters from a 50mW power source.. (2, Informative)

Anonymous Coward | more than 4 years ago | (#30748658)

I suspect the sun is putting out slightly more than 50mW, though...

Re:Yeah, tens of meters from a 50mW power source.. (0)

gweihir (88907) | more than 4 years ago | (#30748332)

Not necessarily, frequency is just as important as voltage and current.

You just failed physics 101. Frequency has absolutely no impact on energy in a signal.

Re:Yeah, tens of meters from a 50mW power source.. (2, Informative)

ancient_kings (1000970) | more than 4 years ago | (#30748350)

Sorry, but you fail: E=hv . frequency is proportional to energy!

Re:Yeah, tens of meters from a 50mW power source.. (2, Insightful)

gweihir (88907) | more than 4 years ago | (#30748564)

Look again into that physics text. Frequency is denoted by "f", not "ny" (no, that is not a lowercase v). The formula you quote relates to the energy of a single photon, no voltage or current in there anywhere and is completely irrelevant to the discussion at hand.

Re:Yeah, tens of meters from a 50mW power source.. (4, Informative)

Rising Ape (1620461) | more than 4 years ago | (#30748728)

The greek nu is the standard notation for frequency in physics, or at least it generally was when I did that kind of thing. f is sometimes used, though less commonly. However, photons are not relevant for RF - the photon energy is so small that the quantum nature of the radiation is not apparent, and it behaves for all practical purposes as a classical wave.

Re:Yeah, tens of meters from a 50mW power source.. (5, Funny)

Rogerborg (306625) | more than 4 years ago | (#30748376)

Frequency effects your ability to absorb the energy. I can only pick up NSA broadcasts on my dentalwork, for example.

Re:Yeah, tens of meters from a 50mW power source.. (0)

Anonymous Coward | more than 4 years ago | (#30748378)

But it has an big impact on the antenna design.

Re:Yeah, tens of meters from a 50mW power source.. (2, Interesting)

toastar (573882) | more than 4 years ago | (#30748550)

You just failed physics 101. Frequency has absolutely no impact on energy in a signal.

Indeed, That's Why the the GHz Barrier was a myth, in fact we should have Thz machines if it weren't for the man keeping them down.

*cough*E = h*(c/lambda)*cough*

Re:Yeah, tens of meters from a 50mW power source.. (1)

gweihir (88907) | more than 4 years ago | (#30748592)

As I said above, that would be the energy of a single photon. Not relevant to energy transmission on the scale we are talking here. Looking up a formula that has energy and wavelength in it is not enough to understand where this formula is actually relevant. Now, if we were talking about single photon detectors, that would be something different. But we are not.

Re:Yeah, tens of meters from a 50mW power source.. (4, Insightful)

aXis100 (690904) | more than 4 years ago | (#30748764)

Frequency plays a massive difference in EM radiation and magnetic induction.

For EM, you really need an antenna that's close to the wavelength, and for 50Hz that's 6000km. For 2.4GHz it's about 12cm.

For induction, frequency affects the overall number of turns required. A 50Hz transformer that copes with 300W is the size of a shoe box, but for a switchmode power supply at 100KHz it's the size of a match box.

Re:Yeah, tens of meters from a 50mW power source.. (2, Insightful)

amorsen (7485) | more than 4 years ago | (#30748090)

That really should have worked, with a sufficiently long antenna. It'll be induction, but that ought to count too.

Re:Yeah, tens of meters from a 50mW power source.. (2, Interesting)

Anonymous Coward | more than 4 years ago | (#30748218)

Much earlier than the mythbusters a german tv-show for kids, the "Sendung mit der Maus" ("program with the mouse") made the point: they held up a neon tube next to a state radio-transmitter and it began to glow. And they explained to the kids, that it will work next to such a high energy radio transmitter, but it is also robbery according to german law. So don't try, kids, unless you don't mind being a thief.

Re:Yeah, tens of meters from a 50mW power source.. (3, Interesting)

lxs (131946) | more than 4 years ago | (#30748254)

How can you steal that what is freely given? Laws are weird.

Re:Yeah, tens of meters from a 50mW power source.. (3, Insightful)

PhilHibbs (4537) | more than 4 years ago | (#30748276)

You're blocking the signal by absorbing large amounts of it. A shared resource should be shared, and not abused.

Re:Yeah, tens of meters from a 50mW power source.. (-1, Flamebait)

Anonymous Coward | more than 4 years ago | (#30748486)

dumbass. lrn2electricity b4 u say retarded shit.

Re:Yeah, tens of meters from a 50mW power source.. (1)

Fluffeh (1273756) | more than 4 years ago | (#30747986)

While I am certainly no degree holder or scholar in this field, I often wondered about the following:

A coil of wire with a current running through it emits a magnetic force. From memory, a magnetic force applied to a coil generates a current. Seeing as the earth is covered in a huge magnetic shell, how come people don't actually generate power this way? Is the magnetic field simply too weak compared to what is needed to generate a current of any value?

Perhaps one of you smart folk here might help me out with this little "backburner" thought that I have had for a while?

Much appreciated,
- Fluffeh

Re:Yeah, tens of meters from a 50mW power source.. (3, Insightful)

Zondar (32904) | more than 4 years ago | (#30748008)

It also has to do with a static field vs a moving field. Make a coil of wire, hold a magnet next to it, hook it to a voltmeter. Notice the coil doesn't have any induced voltage until you move the magnet. You can't get any energy out of a static field, no matter the strength of the field.

Re:Yeah, tens of meters from a 50mW power source.. (4, Informative)

zmollusc (763634) | more than 4 years ago | (#30748010)

I think it is the _change_ in magnetic flux that generates a current in a conductor, not just the presence of magnetism.

Re:Yeah, tens of meters from a 50mW power source.. (1)

scapermoya (769847) | more than 4 years ago | (#30748302)

bingo. it's flux (change in magnetic field), not the magnetic field itself, that produces a current.

Re:Yeah, tens of meters from a 50mW power source.. (5, Interesting)

KulSeran (1432707) | more than 4 years ago | (#30748112)

Nasa HAS tried this.
http://en.wikipedia.org/wiki/Electrodynamic_tether [wikipedia.org]
You can generate electricity as you move around the earth. Being in orbit, you are going fast enough to make worthwhile magnetic flux, and you are free of air resistance that would keep you from deploying the tether if you were lower in the atmosphere.

Re:Yeah, tens of meters from a 50mW power source.. (5, Informative)

Anonymous Coward | more than 4 years ago | (#30748140)

A *changing* magnetic field generates a current. If you just take a coil with some wires attached, and hook up a voltmeter, nothing will happen. Only when you start moving your coil through a magnetic field will you start to see volts. (Earth's field is extremely weak, but with a big coil and a sensitive meter you could see a small current.)

The reason this can't be used for infinite power generation is that the coil will resist movement. Any flow of current generates a magnetic field of its own, and if you do the math, it turns out that the induced current in your coil creates a field in opposition to the field it's moving through. It works against you like a kind of friction, or like air resistance. If you just give the coil an initial kick, it will quickly run down to a stop. In order to generate power you have to keep putting energy into the system.

In other words, you're not draining energy from the magnetic field, you're just converting the kinetic energy you put in.

This is in fact how generators work. A big conductive coil is spun around inside the field of some permanent magnets. If your generator is connected to a water turbine, you're converting the kinetic energy in falling water into the kinetic energy of a spinning coil and thence to electrical energy in a wire.

Re:Yeah, tens of meters from a 50mW power source.. (1)

jo_ham (604554) | more than 4 years ago | (#30748340)

As others have pointed out, you need a change in the field to generate current, either by moving through it or moving the thing making the field. You can observe this effect on a high speed aircraft, where there is a measurable potential difference between the wingtips as it flies though the earth's magnetic field. It's not really strong enough to extract anything useful out of it - you couldn't hook it up to a motor and power the plane, for instance. You'd do better bolting PV panels on every exposed surface.

Re:Yeah, tens of meters from a 50mW power source.. (1)

gweihir (88907) | more than 4 years ago | (#30748344)

A coil of wire with a current running through it emits a magnetic force. From memory, a magnetic force applied to a coil generates a current. Seeing as the earth is covered in a huge magnetic shell, how come people don't actually generate power this way? Is the magnetic field simply too weak compared to what is needed to generate a current of any value?

Perhaps one of you smart folk here might help me out with this little "backburner" thought that I have had for a while?

You have something wrong here: Only a changing magnetic force induces a current, a constant one does not. (Well, technically it does, but at zero Volt, so no current flows.)

Re:Yeah, tens of meters from a 50mW power source.. (1)

pydev (1683904) | more than 4 years ago | (#30748160)

Well, we can't do much about the inverse square law, but we can easily switch to linear units. :-)

Re:Yeah, tens of meters from a 50mW power source.. (1)

mcrbids (148650) | more than 4 years ago | (#30748280)

I see your point, and you are dead on - today!

I remember an episode of Star Trek where the Captain and Spock admire a source of lighting that "produces light, but no heat! - How advanced!" yet, compared to incandescent bulbs, that's an apt description of LED lights, especially those designed for high efficiency [wikipedia.org] !

Let's talk now about Cell Phones - I almost bought a cheapie cell phone for $29 that was about the depth/width/length of a hershey chocolate bar. It sported 2 days of battery life, unlimited text/picture messaging, and (get this!) NO CONTRACT. Compared to the "brick" 1980s cell phone, we have at LEAST an order of magnitude reduction in power consumption and possibly two, by using such techniques and digital packet switching, variable power output, and the like. And this trend is set to continue into the indefinite future [slashdot.org] - we are *still* spending far too much in resources to get what we want.

Now, if you figure that we can improve power conductivity by, oh say, 50%, and can cut power utilization by 100x, (1/10th the amount claimed by Bell Labs) then suddenly, the charge rates from a 150 mw 802.11 radio source 5 meters away actually seems reasonable!

It won't happen today, or tomorrow. But in a few years? Not only possible, but likely!

Re:Yeah, tens of meters from a 50mW power source.. (3, Informative)

gweihir (88907) | more than 4 years ago | (#30748362)

Now, if you figure that we can improve power conductivity by, oh say, 50%, and can cut power utilization by 100x, (1/10th the amount claimed by Bell Labs) then suddenly, the charge rates from a 150 mw 802.11 radio source 5 meters away actually seems reasonable!

It won't happen today, or tomorrow. But in a few years? Not only possible, but likely!

Not at all. Cellphones need something like 100mW...2W RF output to cut though background static and get a signal to the cell tower. And by conservation of energy that means even if nothing at all besides the RF emitter consumes energy, the power consumption will be at least 100mW...2W.

Re:Yeah, tens of meters from a 50mW power source.. (2, Interesting)

Gordonjcp (186804) | more than 4 years ago | (#30748554)

I tried it with a 500mW power source on 460MHz using a pair of resonant quarter-wave aerials. At about one metre separation, it was receiving around -6dBm, or about 250uW. So that's ten times the power, ten times closer, on a lower frequency with better propagation. Ten metres away and 50mW would give -26dBm which my meter won't measure, but is one hundredth the power - 2.5uW. Good luck charging a battery with that.

Gordon MM0YEQ

Re:Yeah, tens of meters from a 50mW power source.. (1)

cc1984_ (1096355) | more than 4 years ago | (#30748628)

The inverse square law and dBm being a logarithmic unit can all go to hell.

What makes you think it's got to be an inverse square law? An inverse square law would apply to something emitted radially, but in the case of a charger, it need not be.

Remote Charging (1, Informative)

Anonymous Coward | more than 4 years ago | (#30747940)

Let's say this RCA product isn't snake oil.

Do you know how much energy it must suck from the 2.4 GHz spectrum to keep it perpetually charged?

Multiply it by the hundreds to thousands of cellphones within one cell ... can you imagine how much power the cell tower much emit in order to charge all those phones?

And the effect of so much energy floating in the air --- what about the effect on human body?

Re:Remote Charging (1)

TheKidWho (705796) | more than 4 years ago | (#30747948)

It has to apply much more power than that necessary to simply charge the phones. Unless of course you carry the cell tower within 1 foot of the cell phone everywhere you go, otherwise you have to start dealing with inverse square laws and all that nonsense sciencey and mathy stuff.

Re:Remote Charging (4, Funny)

flyingfsck (986395) | more than 4 years ago | (#30748088)

Carry a cell tower... I think I'd rather carry a microwave oven - much more compact and convenient, since it can reheat my lunch too.

Re:Remote Charging (1)

Anonymusing (1450747) | more than 4 years ago | (#30748194)

Multiply it by the hundreds to thousands of cellphones within one cell ... can you imagine how much power the cell tower much emit in order to charge all those phones?

FWIW: the article says that the charger makes electricity from "ambient WiFi signals" -- not from the cell tower. Allegedly, at the trade show, "they were able to charge a BlackBerry from 30% to full in about 90 minutes."

Re:Remote Charging (0)

Anonymous Coward | more than 4 years ago | (#30748220)

FWIW: the article says that the charger makes electricity from "ambient WiFi signals" -- not from the cell tower. Allegedly, at the trade show, "they were able to charge a BlackBerry from 30% to full in about 90 minutes."

Most likely they were able to "charge" the phone from full to 30% in 90 minutes.

Re:Remote Charging (2, Informative)

Golden_Rider (137548) | more than 4 years ago | (#30748430)

Actually, the article says "At CES, the device's battery, which I believe was precharged with Wi-Fi power, was able to charge a BlackBerry from 30% power to full power in about 90 minutes." Note the "which I believe was PRECHARGED" part. So they managed to charge a Blackberry from a pre-charged external battery in 90 minutes. Yay. But they never actually said how long it takes to charge the battery in the Airnergy device via wi-fi signals - probably for a good reason, because that would take probably a couple hundred days or more.

Re:Remote Charging (2, Interesting)

mldi (1598123) | more than 4 years ago | (#30748438)

Multiply it by the hundreds to thousands of cellphones within one cell ... can you imagine how much power the cell tower much emit in order to charge all those phones?

FWIW: the article says that the charger makes electricity from "ambient WiFi signals" -- not from the cell tower. Allegedly, at the trade show, "they were able to charge a BlackBerry from 30% to full in about 90 minutes."

That's amazing, because it takes that long to charge my POS cell from the wall with a ... hmmm... ya know, something just doesn't seem right here...

RCA (5, Funny)

MindlessAutomata (1282944) | more than 4 years ago | (#30747950)

Plus, don't let the RCA brand fool you into thinking this must be from a legitimate company

Yes, when I am confronted with an RCA TV, the first thing I think is, "a legitimate company produced this."

Re:RCA (1)

ThrowAwaySociety (1351793) | more than 4 years ago | (#30747982)

Plus, don't let the RCA brand fool you into thinking this must be from a legitimate company

Yes, when I am confronted with an RCA TV, the first thing I think is, "a legitimate company produced this."

Some people are old enough to remember when there was an actual legitimate RCA.

Now get off my lawn.

Re:RCA (2, Funny)

ibsteve2u (1184603) | more than 4 years ago | (#30748594)

Sorry about the lawn. I was just admiring the lightbulb in your lamp post; nice to see Americans using products from American companies like Sylvania. Was that a Zenith TV I saw through your window?

Re:RCA (1)

Max(10) (1716458) | more than 4 years ago | (#30748674)

Plus, don't let the RCA brand fool you into thinking this must be from a legitimate company

Yes, when I am confronted with an RCA TV, the first thing I think is, "a legitimate company produced this."

Some people are old enough to remember when there was an actual legitimate RCA.

Now get off my lawn.

Or you'll whip them with a pair of RCA cables?

Introducing the all new RCA whoopass whipenergy device! It's not wireless, but it gets your point across time after time after time.
Brought to you by RCA, the first company in the world to break the 1 Mbps barrier over CAT9 cable [wikipedia.org] .

Re:RCA (0)

Anonymous Coward | more than 4 years ago | (#30748272)

Plus, don't let the RCA brand fool you into thinking this must be from a legitimate company

Yes, when I am confronted with an RCA TV, the first thing I think is, "a legitimate company produced this."

I prefer Magnetbox or Panaphonics myself.

Not if you... (0)

Anonymous Coward | more than 4 years ago | (#30747954)

...microwave it. :)

30 seconds on full power (1)

jamesh (87723) | more than 4 years ago | (#30747968)

Maybe we just need to remove all the shielding off our microwave ovens and run them on full. That should pollute the immediate vicinity with enough power to charge the devices.

Re:30 seconds on full power (1)

benchbri (764527) | more than 4 years ago | (#30747972)

But then the cell phone frequencies would be jammed...

Charge phone or make a call.... hmmmm....

Re:30 seconds on full power (2, Informative)

tagno25 (1518033) | more than 4 years ago | (#30748166)

Cellphones do not use 2.4Ghz, so the frequencies would not be jammed. The problem is that the people using them would be cooked or at least feel a slight pain.

Re:30 seconds on full power (0)

Anonymous Coward | more than 4 years ago | (#30748436)

Cellphones do not use 2.4Ghz, so the frequencies would not be jammed.

Just set it to low instead of popcorn.

Re:30 seconds on full power (1)

weirdo557 (959623) | more than 4 years ago | (#30747974)

can you type in bold, i cant read your comment through these cataracts.

Let's pump MORE wattage of EM radiation in the air (-1, Troll)

Anonymous Coward | more than 4 years ago | (#30747970)

for stupid, trivial stuff

and I'm sure 70% of the population won't get cancer in their 30's

Re:Let's pump MORE wattage of EM radiation in the (1)

dasmoo (1052358) | more than 4 years ago | (#30748270)

2.4Ghz waves aren't small enough to damage DNA.

In answer to the headline, let's simply say (4, Insightful)

MrEricSir (398214) | more than 4 years ago | (#30747978)

YES

Aaah... BUT... (1)

denzacar (181829) | more than 4 years ago | (#30748552)

You are not considering the possibility that this device is not intended for your average user.
Maybe it was envisioned with a more... active crowd in mind.

You know... the kind of people who would find the prospect of running up to one of these [wikipedia.org] a valid possibility.

Also, it would make a GREAT plausible denial device for the active denial system (PDDfADS).
Hang one of those around your neck and you can claim that you were just trying to charge your phone (and not the ADS), when you are arrested for whatever activity it may be that required the use of the ADS on you in the first place.

Not so useful now, but has potential (1)

Zebai (979227) | more than 4 years ago | (#30747998)

I don't think it was necessary to discredit RCA since you made no effort to back up that statement but I personally find the technology interesting.

I hold no misconceptions that this could keep any device perpetually charged however If the technology advances enough you could perhaps greatly extend battery life beyond its actual storage amount if it is always attempting to replenish itself to whatever is available as an energy source. It could turn your average 5 hour battery into a 6 hour battery, with no extra capacity. While I'm probably exaggerating the actual benefit of this current model, it could provide potential in the future.

Re:Not so useful now, but has potential (1)

Yetihehe (971185) | more than 4 years ago | (#30748048)

The problem is: there is too low potential for this to work.

Re:Not so useful now, but has potential (1)

Terje Mathisen (128806) | more than 4 years ago | (#30748064)

Increase from 5 hours to 6 hours?

No way!

It _is_ possible to run electronics with over-the-air power, witness all the millions and millions of passive RFID tags out there.

However, the power density required to run/charge a cell phone or laptop is simply way out of range, unless you want to cook the user holding the phone at the same time.

Terje

Re:Not so useful now, but has potential (5, Funny)

tsm_sf (545316) | more than 4 years ago | (#30748126)

...unless you want to cook the user holding the phone at the same time.

Your ideas are intriguing to me and I wish to subscribe to your newsletter.

Re:Not so useful now, but has potential (0)

Anonymous Coward | more than 4 years ago | (#30748170)

"It _is_ possible to run electronics with over-the-air power, witness all the millions and millions of passive RFID tags out there."

Also my electrical tooth brush is charged OTA. Granted the distance is just a few millimeters from the charger, but it is possible. At least there are no contacts that get dirty/wet.

Re:Not so useful now, but has potential (1)

gweihir (88907) | more than 4 years ago | (#30748452)

It _is_ possible to run electronics with over-the-air power, witness all the millions and millions of passive RFID tags out there.

Indeed. And they work when placed how close to the reader that also powers them? Typically less than a meter unless you use a highly directional (bulky) antenna. They do not run on ambient RF at all!

Re:Not so useful now, but has potential (0)

Anonymous Coward | more than 4 years ago | (#30748072)

a typical phone uses 0.6 watt to operate. this stuff generate 50mw if directly attached by cable to a wireless antenna (per regulations) but you can obtain up to 150mw from a long range device. on this assumptions, your phone will receive a third of is operating power, effectively extending his operation of a third

BUT

if you are this close to an antenna, you can just plug yourself on the power source the same antenna is using.
if you are not attached to an antenna, the power received decreases with the square of the distance - or _more_ if you're not in the antenna cone of transmission (which is a doughnut even for omnidirectional antenna).

throw in some wall, generic inefficiency of any kind of power extraction and you'll get nothing out of the wifi.

Ask Slashdot: Ten Minutes Hate? (5, Funny)

Tsunamio (465339) | more than 4 years ago | (#30748062)

I'm sure we can look forward to a vigorous debate, where both sides bring up excellent points. I certainly cannot say where the slashdot community will land on this question, and the article certainly doesn't give any hints! Thanks, Ben, for your valuable question, and I hope you find the answers both challenging and enlightening.

Re:Ask Slashdot: Ten Minutes Hate? (1)

francium de neobie (590783) | more than 4 years ago | (#30748084)

If there's a debate on whether this technology can work, it goes like this...

Chuck Norris roundhouse kicked conservation of energy in the nuts, and he charged up his iPhone from his WiFi router's signal in 1 minute, 100 meters away!

If you're getting -70dBm, and Chuck Norris's iPhone is getting -70dBm, Chuck Norris is getting more power than you!

Does the Density of signal count? (1)

Skythe (921438) | more than 4 years ago | (#30748370)

If it does, i'd imagine CES to be the _perfect_ testing ground for such a product. Elsewhere? Not so sure..

Back of the envelope... (5, Informative)

doishmere (1587181) | more than 4 years ago | (#30748096)

Assume a wireless router broadcasts at 1W, uniformly outward. Suppose the charger has an effective surface area of 4" * 2", or about 50cm^2. Assume the charger is 10m away fro the router; then the charger can receive no more than (1W) * (50cm^2) / (4 * pi * 1000cm * 1000cm) = 4 * 10^-6 W. A Blackberry battery on Bestbuy.com claims to store 1100 mAh @ 3.7V of energy, so the device could charge a powered-off Blackberry in (1100 mAh * 3.7V) / (4 * 10^-6 W) = 116 years... I'm wrong, or the device doesn't work as claimed.

Re:Back of the envelope... (2, Funny)

doishmere (1587181) | more than 4 years ago | (#30748100)

Of course, I can't be wrong: http://www.xkcd.com/687/ [xkcd.com]

Re:Back of the envelope... (0, Flamebait)

MancunianMaskMan (701642) | more than 4 years ago | (#30748176)

Thank you for this informative comment: the depth of ignorance [slashdot.org] exposed above and subsequently modded "informative" are sickening.

is this a slashvertisement? (-1, Flamebait)

ChipMonk (711367) | more than 4 years ago | (#30748132)

Of all the techie and semi-techie blogs I follow, this is the first place I've seen this "airnergy" thingamabob mentioned.

Then again, I should expect this from kdawson.

Re:is this a slashvertisement? (1)

mgblst (80109) | more than 4 years ago | (#30748502)

Well it has been on techcrunch, techMeme, engadet, gizmodo, ycombinator and many more.

Not sure what you are following?

it's not snakeoil! (3, Funny)

pydev (1683904) | more than 4 years ago | (#30748148)

Obviously, you put this thing in the microwave, set it to High, and let it charge for 30 minutes.

(Please let it cool down before removing it from the oven.)

Some thoughts. (1, Funny)

thaWhat (531916) | more than 4 years ago | (#30748174)

I am of the belief that yes, you can re-charge your 'phone's battery from an R.F. power source (after all, it works for RFID).
There are IMHO two caveats;
Your 'phone needs to be in standby, since when talking, you'll be using far more energy than the cell can provide.

Any active users will suffer reduced signal-strength due to all the passive users re-charging their 'phones. This power has to come from somewhere and that place will be the cell transmitter. Given enough 'phones re-charging and you won't be able to make/receive a call because your 'phone won't be able to hear the cell due to all the other 'phones sucking all the signal from it...

Just a thought.

C:\>

Re:Some thoughts. (0)

thorndt (814642) | more than 4 years ago | (#30748230)

One small correction: The cell tower transmits the same signal power level, no matter where it goes or how it's used. So if a cell tower out in the Mojave desert puts out, say, 5 kilowatts and there's no cell phone around to receive its signal, then....the cell tower put out 5 kilowatt. Phones that recharge from the cell towers' transmission won't effect anyone else's phone reception.

Re:Some thoughts. (1)

Liambp (1565081) | more than 4 years ago | (#30748326)

This is not true - if you extract energy from the local field then you are going to reduce the local field intensity. This is certainly going to screw up the reception of people around you. Its a bit like putting a solar panel in front of your neighbor's window. You may not be putting any extra load on the sun but you are certainly putting your neighbour in the dark. I vote snake oil in any case because even though it is feasible to extract energy from an electromagnetic field the energy densities involved are going to be miniscule unless you are sitting right on top of the transmitter (inverse square law as mentioned above). If you do put this device right on top of the transmitter and suck energy out of the signal there then you will kill the signal for everybody else.

Re:Some thoughts. (1)

thaWhat (531916) | more than 4 years ago | (#30748368)

Not quite. Yes the cell tower will put out 5kW, but each user (even if they eren't recharging their 'phone) will put a load on the cell. For a down-town cell, this load could well be significant. The RFID tag example is a good one.
The RFID sensor is a simple transmitter radiating at a specific frequency. The RFID tag represents a load to the transmitter. the sensor looks at the current being drawn by the transmitter (and by proxy, the tag) and decodes the current pulses into voltage pulses which are then decoded into a serial data stream. This is not how cells work. They transmit at one frequency and receive on another. BTW, I guess that I should mention that we are talking about 2.4 GHz here which means that cell-phone communications should be fine, but they'll annihilate any WiFi hotspots nearby, since that's where they'll be drawing their energy from. WiFi tends to run at about 1W. Hardly enough to charge more than say, 20 handsets...

Not arguing, responding.

C:\>

Re:Some thoughts. (1)

gweihir (88907) | more than 4 years ago | (#30748474)

I am of the belief that yes, you can re-charge your 'phone's battery from an R.F. power source (after all, it works for RFID).

It is not the same as RFID. RFID does not have batteries and is only active ("on") when placed into an EM field of the right frequency.

This is embarassing (1)

Animats (122034) | more than 4 years ago | (#30748190)

This is embarrassing. Embarrassing for Thompson, which owns the RCA brand. Embarrassing for press who took it seriously. Serious career trouble for whomever authorized licensing the name to the clowns behind this.

We'll probably hear some disclaimer from Thompson shortly.

Tesla? (5, Funny)

MikeFM (12491) | more than 4 years ago | (#30748224)

Tesla seemed to think this idea was workable. Can't say about RCA's product but I'll trust Tesla.

Re:Tesla? (1)

GWRedDragon (1340961) | more than 4 years ago | (#30748300)

The problem is not that wireless power is impossible, rather, that 802.11 access points cannot (by law) output a signal strong enough to provide any meaningful power at a reasonable distance.

What we really need now is super-beefy access points. Allocate some spectrum so that I can set an access point to transmit at 100kw. That'll get some power! Just don't stand close to it...

Re:Tesla? (2, Funny)

adolf (21054) | more than 4 years ago | (#30748494)

Kid to mother: Mommy, why doesn't it ever snow over by Mister Dragon's house? And why are the trees always green in the winter? How come I feel warmer when I stand on his sidewalk?

Re:Tesla? (1)

gweihir (88907) | more than 4 years ago | (#30748488)

Tesla seemed to think this idea was workable. Can't say about RCA's product but I'll trust Tesla.

Oh, it is. If you can live with horrible efficiency, unless very close to the sender. For typical ambient RF, you are lucky to get 1 miliwatt out of this, far less than is usable as a battery charger. This is really basic physics stuff. While the idea is sound, it just does not work with the numbers found in practice.

Well two things (3, Insightful)

Sycraft-fu (314770) | more than 4 years ago | (#30748492)

1) Note that Tesla never got wireless power working. He liked the idea, but he couldn't make it work. Also note that to this day we still don't have it. That should tell you something. The problem, it turns out, is that EM power decays logarithmically with distance. So a little more distance translates to large losses in power. You have a 1 watt transmitter and it is only a few milliwatts when you get a bit away from it. It would be extremely inefficient to transmit power through the air, even ignoring other problems.

2) Tesla was nuts, like "lock him in a soft room" crazy. He was brilliant, don't get me wrong, but he was also crazy. The guy had some really wacky ideas, along with some extremely genius ones. Just because Tesla thought something would work, doesn't mean it would.

Re:Tesla? (2)

argent (18001) | more than 4 years ago | (#30748532)

Tesla blacked out Colorado Springs trying to get enough power into the air to make broadcast power work. He thought aliens were talking to him. He was a genius, but he was also missing a few screws.

back to basics (5, Insightful)

vacarul (1624873) | more than 4 years ago | (#30748244)

I'll get more energy with a hand-crank generator...

Re:back to basics (1)

mldi (1598123) | more than 4 years ago | (#30748426)

I'll get more energy with a hand-crank generator...

LOL - a bit of sense through the muck.

Re:back to basics (5, Funny)

MobileTatsu-NJG (946591) | more than 4 years ago | (#30748696)

I'll get more energy with a hand-crank generator...

... depending on which picture is in front of you.

Snake Oil (3, Informative)

gweihir (88907) | more than 4 years ago | (#30748260)

Not enough energy available. Would probably not even offset self-discharging unless a pretty large antenna is used. You can fake a demo though with a highly directional antenna to beam in a wireless signal. Not realistic at all and inefficient as hell.

I am constantly amazed at what people are willing to believe.

Re:Snake Oil (0)

Anonymous Coward | more than 4 years ago | (#30748572)

If a "highly directional antenna" is all it takes for this to work, then I wouldn't call it so fake. Wouldn't it be easy to track the position of a few target objects (cellphones, iPods, etc.) lying around the house and direct a "beam" of charge at each of them?

Re:Snake Oil (1)

MattskEE (925706) | more than 4 years ago | (#30748710)

If a "highly directional antenna" is all it takes for this to work, then I wouldn't call it so fake. Wouldn't it be easy to track the position of a few target objects (cellphones, iPods, etc.) lying around the house and direct a "beam" of charge at each of them?

It would be quite possible to make a tracking CW transmitter either using a gimbaled antenna (unlikely) or phased array (better, but quite pricey), the problem is that it will be incredibly expensive, even if it reaches mass production, especially if you want it to have anything approaching a useful range. This thing would also be be extremely inefficient.

Then the next problem is that if you have a useful amount of charging RF power incident on the device, you have to make sure that it doesn't interfere with normal cell-phone operation. Obviously it can't be done at a cell-phone frequency, and there will be additional challenging (i.e. expensive, space-consuming, and range-reducing) filter component requirements necessary to prevent saturating the cell phone's receiver.

Re:Snake Oil (2, Insightful)

Spatial (1235392) | more than 4 years ago | (#30748576)

I am constantly amazed at what people are willing to believe.

Ignorance makes you gullible. And in general people are pretty ignorant about technology.

Re:Snake Oil (1)

johncadengo (940343) | more than 4 years ago | (#30748672)

But why... Why would anyone ever do such a thing!

How it worked (1)

DMorritt (923396) | more than 4 years ago | (#30748296)

If you read the article:

"Airnergy takes the energy created by wi-fi signals and stores it in a rechargeable battery. At CES, the device's battery, which I believe was precharged with Wi-Fi power, was able to charge"

The key words are "the devices battery, which I believe", if he can charge a mobile battery from another battery then this is nothing new, however the charging of the "devices battery" is what is questionable in my mind, fooling yourself into thinking that the guy was sat in McDonalds or at home and powered if off his neighbours wifi is stupid.

Re:How it worked (1)

AlexiaDeath (1616055) | more than 4 years ago | (#30748372)

Well, I can see it might actually work as sort of self charging emergency battery. You leave it in your backpack for months and when you need it you can have a little backup power and you can toss it back in the pack wen empty for another few months of recharge. On the other hand, I know someone who carries a regular pack of AA batteries bundled and equipped with a charger end with same purpose and I'm willing to bet its cheaper.
So, as a regular charger - no way. Snakeoil.
As an emergency battery - maybe but who would buy such a thing?

There ain't no RCA (2, Informative)

Wansu (846) | more than 4 years ago | (#30748334)

  Plus, don't let the RCA brand fool you into thinking this must be from a legitimate company: RCA hasn't existed as anything more then a licensed brand name for a couple of decades.

You got that right. Neutron Jack cannibalized RCA in the late 80s, selling the consumer electronics division to Thompson. About 12 years ago, they sold chinese company TCL the right to use the RCA name on TVs and other products.

They ought to replace Nipper with one of those chinese hounds with all the extra folds of skin. HIs master's voice is in chinese.

Nokia's working on this too (2, Informative)

Sockatume (732728) | more than 4 years ago | (#30748404)

Nokia proposed a power-harvesting (and power-sipping) handset over the summer last year, to derive its power from cellular signals rather than wi-fi. Although their target amount of 50mW is way off, they claim to have a prototype that can pull in a few milliwatts, which inspired a mixture of scepticism and existential terror from researchers in the field.

Re:Nokia's working on this too (1)

gweihir (88907) | more than 4 years ago | (#30748510)

Nokia proposed a power-harvesting (and power-sipping) handset over the summer last year, to derive its power from cellular signals rather than wi-fi. Although their target amount of 50mW is way off, they claim to have a prototype that can pull in a few milliwatts, which inspired a mixture of scepticism and existential terror from researchers in the field.

That would be very incompetent researchers then, as the "a few miliwatt" figure is very old and typically found in a classical radio experiment for teenagers. Anybody with a clue about RF electronics will know it and not be surprised. The magic circuitry is called a "diode", the only thing you can really optimize is the antenna, and the potential there is not limitless and will not scale up to 50mW, unless you are willing to lug around a square meter of cell pone.

Re:Nokia's working on this too (0)

Anonymous Coward | more than 4 years ago | (#30748548)

My Nokia E66 uses 1W idling according to their application. I don't see a possible benefit in this.

Wireless power transmisstion is possible ... (1)

golodh (893453) | more than 4 years ago | (#30748530)

Wireless power transfer is possible, for example MIT researchers have shown it to work across 2 metres in 2007 (see http://web.mit.edu/newsoffice/2007/wireless-0607.html [mit.edu] ).

The crux is to use "Magnetically coupled resonance" to achieve efficient power transfer to prevent the vast majority of power from being broadcast into space (read wasted) when no receiver is present to absorb it. Unfortunately that very feature seems to severely limit the transmission range.

So I wouldn't worry about long-distance power transmission through the air just yet.

I'm more worried about plans for space-based power transmission which were recently green-lighted in California. For example, what happens when the beam from such satellites shifts from the intended receiver area to, say, a residential block?

According to http://en.wikipedia.org/wiki/Space-based_solar_power#cite_note-intensity-41 [wikipedia.org] at the center of the downward beam, we would be looking at 23 mW/cm2 (and 1 mW/cm2 outside the center), compared to OSHA workplace exposure limits for microwaves, which are 10 mW/cm2. Not bad, but not good either. Suppose someone goofs and directs the beam onto a kindergarten and leaves it there for a week. What then?

Those 23 mW might not look like much, but it's still 230 W/m2, and it's radio-frequency which penetrates far deeper than visible light. I simply don't know how detrimental that is, but I'd like to be sure of the potential long-term effects before anything like that is built, let alone switched on. I'm certainly no Luddite, but in the light of e.g. findings like these (see http://www.isracast.com/article.aspx?id=57 [isracast.com] ) about the detrimental effects of 2mW of 1.1GHz radiation on eye lenses I feel we ought to be careful. Signal-level transmission at 2mW is one thing, but power level transmission at 23mW/cm2 is something else.

re: (0, Troll)

vodomecs (1714142) | more than 4 years ago | (#30748538)

That sounds cool. It might actually work!

Really cool. If I combine some of these boxes.. (0)

Anonymous Coward | more than 4 years ago | (#30748718)

maybe I can run my 3g wireless access point on them?
If I place them close enough I might not even need any other wifi signals..

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