CES 2010: Yet Another Amazing Wireless Charging Option - RCA Airnergy Hotspot Harvesting Charger & Battery Pack

By Kevin Michaluk on 12 Jan 2010 06:47 pm EST

Sick of reading blog posts and seeing videos yet about smartphone charging solutions? Apologies for that, but seriously, there was a TON of it going on at CES 2010. One of the COOLEST things going on, which I didn't get to check out in person but you can see in the video above courtesy of ohgizmo, is RCA's hotspot harvesting charger and battery pack. The devices literally leach the energy that's floating around in WiFi signals and transfer it into the charger and/or battery pack, now making it useable to recharge or power your device. Tesla would be proud. Honestly, I've never been one to freak out over all the invisible stuff that's floating around in the air, but seeing gadgets like this has me thinking the hot items we'll see at CES 2011 are tin foil hats and tin-lined underwear which protect us from the effects of this stuff. :)

[ hat tip ]

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CES 2010: Yet Another Amazing Wireless Charging Option - RCA Airnergy Hotspot Harvesting Charger & Battery Pack


Plugged into a wall charger it takes about 90 minutes to charge from 30% to 100%... so I doubt his claim of 90 minutes it true unless the device collects the energy over a much longer period of time, stores it in an internal battery, than can charge your device once you hook it up.

Cool if it works as advertised... but we didn't see a demo to prove anything.

I'm thinking that this is like a rechargeable battery itself that constantly harvests the wifi around it, stores it, and then transfers it to your phone. I'm guessing if this were out of juice completely, and you walked into a hotspot, plugged it into your phone, it would take longer than 90 minutes to charge. Just guessing since I have never even heard of a technology.

Wow, but I won't believe that it charges the phone that fast just from harvesting energy from wifi until I see the real working product. I reallllllly hope that it is true though.

I'm pretty sure the 90 minute charge time quoted is based on the Airnergy device collecting and storing the energy from hotspots over several hours/days and then charging the Bold from its internal battery.

I'm a little rusty with physics, but looking at the M-S1 battery specs, it is rated for 1450mAh at 3.7V.

P = I*V = 1450 * 3.7 = 5365mWh

802.11g specs maximum radio power output to be 100mW

Assuming 100% power is collected by the Airnergy unit, it would take 5365/100 = 53.65 hours to gather enough energy to fully charge a BlackBerry M-S1 battery from 0% to 100%.

In the real world there's no way the Airnergy can collect 100% of the power output of a WiFi access point, so charging time would be much longer than the theoretical number calculated here.

Of course I'm not an engineer so my calculations may be off. ;-)

Your numbers are right! There is an ability to change power output. You can also use various other circuitry to change the power delivered. So, though your numbers are correct in one sense, your theory is far from accurate as there has to be atleast one type of converter in there. I would love to get a hold of those schematics or crack one open myself!

Technology like this is definitely the future - although I still think my charging pod is pretty convenient :)

Woah woah woah wait just one minute. If you're planning to use nab my wireless routers signals and convert it to power I'm going to have to charge you a small fee...

My question is... would this make a router work harder? Cause interference?

This would not require any additional power from the wi-fi router, because it is simply using the signal that it is putting out anyways. Overall power usage would remain unchanged which is what makes this a very "green" solution.

It could however cause some signal interference. Probably not much, but certainly non-zero.

I doubt it would cause signal interference unless the device was inbetween the wifi signal generator and the computer you were using. In order to cause some sort of signal interference it would need to put out or even repeat the same signal at a slightly different wavelength or amplitude or something. But as a pure receiver, it would only cause as much interference as a wall or book or even a chair. What it would not do for your signal (which would reduce it by so small you wouldn't ever even notice it) is cause no. Bouncing off the device to happen like a wall does.


the actual signal interference would be very small. Probably the equivalent of holding a frying pan between your router and your computer.

Still there would be "some" interference...

This would be soooooooo sweet just walking around getting your battery charged at like starbucks or at home or anywhere with a 2.4ghz wifi signal, i have been told this technology has actual thought of a long time ago but no one has implemented it yet, this is sweet

Seriously, this has GOT to be a hoax. See the first set of comments on the ohgizmo link in article for the very compelling arguments that call BS on this device.

Not a hoax. This is proven technology and has been used to power RFID chips for awhile now.

That said there are some real concerns about the overall effectiveness of such a solution. Mainly if it would pick up enough energy to power a full days worth of blackberry use, which is rather doubtful...

I had trouble buying the idea of wireless charging when they came out with the concept. Look at the "wireless" charger from dell. Its bigger than the laptop itself, and has to pretty much sit on it. This is with a transmitter with lot more power that could be radiated.

Now, a device that "harvests" energy from WiFi? give me a break :). If your wifi transmitter outputs 100mW of total power, by the time it gets to your receiver, that power is going to drop to probably in the order of 100's of uW (unless you're on top of that transmitter itself). Good luck charging that gadget within few days even!

Great on paper, but wireless power transmission will always be a pipe dream over any significant distance. Air just doesn't make a good conductor! In communication it works well, because the actual power at the receiving end does not matter so much as the signal-to-noise ratio (we're after information here not energy). So, even though signal might be very low power, as long as noise power is much lower than signal power, you can adequately amplify the signal at the receiving end, and you're good. For power transmission, you can't "amplify" energy. All you can do is minimize the losses in air (thus, guys at MIT and companies are using concept of resonance to cancel out the capacitive effect of air with inductance in the transceivers, and thus realize a lower impedance path for energy transfer). However, there is still lot of losses, and distance between receiver/transmitter has to be relatively very close.

I wouldn't put my stock in this field for sure :)

Having said that, there are niche application for powering very very low power sensors/devices with power consumption in the range of 100microWatt to 10milliWatts with "energy harvesting". But in this case, they are harvesting energy from power transformers, and high voltage lines (>4.4 kV) that are carrying power in kiloW to Megawatt levels.

With WiFi? Maybe future nanodevices with extremely low power consumption. Blackberrys? dream on :)

I thought that boffins have been trying for years to transmit energy over the airways. And now all of a sudden these guys have done it.................. I find this very hard to believe.
The last I heard (12 months ago maybe) was that some company where able to receive transmitted energy around 2m away from a tyre sized transmitter using a plate size receiver.

Time will tell if this is fair dinkum or just a con

: kgns
The last I heard (12 months ago maybe) was that some company where able to receive transmitted energy around 2m away from a tyre sized transmitter using a plate size receiver.

I believe that they are not transmitting energy they are simply trapping the wifi signals and "converting" they to an electric charge

Hi Tws49,
Your not the first person to tell me I don't know what I'm talking about ;-) (In fact I hear it a alot)
You could be right, but why isn't everyone powering up their houses off all those free radio transmissions out in the ether?
I presume that it's because if it does work it's pretty inefficient :-(

There is no way in the world that this device can harvest enoguh energy to charge a cell phone battery. Power available at the antenna of any receiver - even those receiving signals from 50,000 Watt transmitters, is in the microwatt range. A wifi transmitter transmits 100 milliwatts - thats 1/10th of a watt. Some go as far as 800 milliwatts. Since you are close to them you will get, again, microwatts (millionths of a watt)at your antenna. You cannot get more than that - it's just not there. Even if you wrap the transmitters antenna with something to absorb all the power, you will still get a very small amount of power to charge. Not enough to be practical, and maybe not even enough to keep up with cell self-discharge. And of course if you use ALL the power to charge, you no longer have wifi. Just a stupidly expensive and inefficient battery charger.

Will they sell these? Yes. To suckers who know nothing about basic physics.

Couldn't they come up with a better person to present such a hot item. Jeez, this guy could barely speak!

I wonder how this affects the wireless network itself. It is, after all, placing a load on the network signal strength and is pulling power from the wireless access point. Just because we don't pay for it that doesn't mean that it is "free" energy. It has to be produced and transmitted. If we use part of the WiFi signal for battery charging then that means there is less for data transfer and the output of the WiFi hotspot must increase to keep the same signal strength.

The energy is free in the sense that these signals are already sent out by the router regardless of if this energy is captured or not on the other side. While non-zero disruption to the wi-fi signal would be very minimal.

It is from the internal device battery that charges the external device's (cell phone, whatever)battery. The wireless device battery get TRICKLED charge over a period of time.

As far as the device using up WIFI signals, when ever a person turns on a radio or tv, the radio or tv broadcast signal does not decrease, so why should a WIFI signal get gobbled up by this device? Whenever someone opens their eyes the amount of light in this world doesn't decrease and the world get dimmer. LOL

This looks like a great product! and so what if it takes a lil longer then 90mins, you'll be able to charge in a hotspot with out a wall hook up. Think of the times you wish you had that?? Which they can't be too far off if they already have a normal battery in pre-production. You would think they would figure out the time frame for a charge before they make an actual battery.

First of all, RCA is just a licensing name, the company itself has not existed for a couple of decades. The RCA label is available for licensing by any company that wants to slap it on their product.

That aside, there is not enough energy produced by wireless Wi-Fi signals to make this fly as they are proposing. Some learned people estimate charging a battery could take decades using this method. So while the concept sounds good, I doubt it will amount to anything.

Since standard Wifi uses 2.4 GHz (5 GHz for 802.11a). Does this mean that this unit may also charge if you have a 2.4 GHz cordless phone? Or what about a Microwave oven, since it also gives off energy at 2.4 GHz?

2.4 GHz covers a lot of area. WiFi uses only 11 channels out of the thousands of channels in that range. Cordless phones can be utilizing anywhere from a single channel, all the way to 50+, but just far enough away from the Wifi channeling to cause interference. BlueTooth is the same way. So there is a possibility it could charge of the signals of a cordless phone, but only if the phone is in use. Whereas WiFi is constantly transmitting until someone or something happens to turn it off.

Now I wonder why is it taking so long to create a device like this? But why did they want it to harvest RF energy on the 2.4 GHz? Would it not work better if it were to lets say harvest the local FM radio broadcasts which cover more area and a lot stronger signal?

Taken from http://www.ohgizmo.com/2010/01/09/ces2010-rca-airnergy-charger-harvests-...

Here's some math. Long story short, by my calculations, 100% efficiency and absorption at 5 feet away from a 100mW home router, (reasonable figures), it would take 34.5 years to charge that blackberry battery.

It's not a Dyson Sphere, so you only get the power that hits the antenna.
Surface of a sphere = 4pir^2, r = 60" (5 feet).
Surface area of a 5' sphere = 45,216 square inches.

The device appears about 2" x 3" = 6 square inches.
The device then picks up, best case, 0.000133 of the power out from the router, which is 100mW, so.. 0.0133mW

If you leave it there for 24 hours, 0.0318 mWh are stored.
According to Will's battery, it has ~4,000 mWh capacity.

So, it would take 12,579 days, or 34.5 years, to charge your blackberry battery once, presuming 100% absorption, no losses.

I call BS. Even adding up all the laptops, cell phones, routers, portable phones, everything, all the noise in the RF spectrum that could hit that device, I don't see it charging the internal battery even in a week.

Of course, once the internal battery is charge, hey, no problem, you can dump that power into whatever you want to charge, easy.

I don't know much about RF though. Did I miss anything? How's my math?

I've read all the arguments about why it won't work, why it can't work, why this and why that. But I feel like people need to take a step back and realize a couple of things:

This guy had probably no idea what he was talking about. He seemed more the salesman then the researcher, because he failed to convey any ideas clearly. How does it really work? None of us know - we are all speculating. Perhaps it doesn't just draw WiFi energy. Perhaps it draws a number of sources. But even if its slow, here are the applications I see with the Battery Sized version:

Ideally, sure, you want enough juice to power the device at the rate on consumption. But even if that ISN'T possible (and I very highly suspect it isn't), any level of positive charging on the battery will result in a SLOWER DISCHARGING battery. My 8900 will run approximately 36 hours of moderate usage. That is roughly 2.78% of my battery level per hour. Now - lets assume it takes 100 hours to fully charge using this technology. 1% per hour. That means I'd actually only be draining approximately 1.78% of my battery per hour: That pushes my battery life to 56 hours and ten minutes (all things being equal over time).

I don't know about you, but I'd pay for a battery that gave me a 56.05% increase in battery life. Sure - the heavier user you are, the less benefit this has - but there IS some potential gain.