RCA Charger Draws Electricity from Wi-Fi Signals

[sublifer]

It'd be neat to power small PCs with this... HTPCs or netbooks... without the need for power cords.... that would rock!

 

[Socnom]

[citation]But.. "The rechargeable battery resides within the Airnergy device, and will automatically begin charging once it comes in contact with Wi-Fi signals." the battery is what charged the blackbury. And if I need to carry a separate battery it'll be wall rechargable. ... Now an emergency LED flashlight that was always charged ...[/citation]

exactly, it was the battery inside that device. They never mentioned how long it takes for that battery to recharge by wifi, only that it is possible.
Now, if you know even High School physics, you know that the more components introduced into a circuit, the less efficient it becomes. Wifi -> battery -> cell battery is inefficient.
Now, what would be interesting would be if this device could use multiple Wifi sources. In my dorm, I have over 10 wifi networks that i can connect to.

 

[WheelsOfConfusion]

[citation][nom]Socnom[/nom]exactly, it was the battery inside that device. They never mentioned how long it takes for that battery to recharge by wifi, only that it is possible.[/citation]
It doesn't matter which battery it's supposed to be charging, it's still not going to be enough charging to make it practical. Are you going to leave the RCA unit next to your wifi for a week just so you can recharge your phone's battery in an hour?

Now, what would be interesting would be if this device could use multiple Wifi sources. In my dorm, I have over 10 wifi networks that i can connect to.

The best case scenario for wireless transmission is that power drops off as the square of distance, or in other words VERY quickly. In reality, with omni-directional non-point-source antennae like the ones in 802.11 wireless networks, if your charger is even a few yards away from the antenna of any wifi hotspot, you'll probably get no useful power to overcome the resistance of a partially charged battery enough to recharge it, even if there are ten hotspots all in the same floor. These wireless transmitters are just extremely low-power radios, they only have to be able to push a detectable signal a few tens of yards.

 

[dawolf74]

@ Eric and Wheels

I will refer you to basic texts on electronics and electricity.

There are ways to take a charge and use it to create bigger charges.

Many.

I will not go into it here because it could fill an entire lecture course, but it is obvious you have nothing more then a pedestrian understanding of electricity.

(transformers, capacitors and using a small charge to create a magnetic field that creates a larger charge, you also leave out the obvious that a .1 charge is out there but there is an exponential effect in energy harvesting when taken in from all directions. By your logic, generators would not work because there is not enough free electrons in the air to be coaxed into the copper cables by the magnetic fields created by the generators. As in, generators do not generate anything but a spinning magnetic field that coaxes electrons out of the air, it does not actually create electricity)

I find that one of the most misunderstood physics by anyone is electricity and magnetic fields.

 

[Honis]

[citation][nom]Razor512[/nom]nope wifi is not effected as a transmitted signal can have an unlimited number of listeners, as long as they don't broadcast they wont hinder the signal for others.they need to include this technology in all battery powered devices, it will be sure to increase the run time.[/citation]Yes it will. Every wireless signal has a limited number of listeners and a range based on where those listener are and how much power they're drawing from the signal. For example, you have an antenna, and 2 listeners in a straight line. The antenna is a 1W antenna and person a has a 500mW draw on that signal. The second person is only going to be able to draw the other 500mW and no more. If the first person increases his draw to 1W, that second person wouldn't even know a signal was being generated. TV, Radio, WiFi, etc don't have this problem (yet) because they are pumping out extra wattage to increase range. If people started running around drawing signals out of the air this will become a huge problem because it will severally decrease the intended range of the signal and hamper its target listeners.

This has never been used as a power source because it is horribly inefficient. An antenna can only direct it's signal so much before it spreads to unintended areas (like outer space) and the antenna can't detect where more power is needed, its just always on. With wired power, you lose some in the transmission but most of what you're sending goes directly to its intended target and it can determine based on the amps drawn where more wattage needs to be added.

 

[Someguyperson]

Did anyone else think someone shot the charger right in the middle when they first looked at the picture?

 

[tommychan]

If this technology works properly and charge batteries live while picking up wi-fi signals, the first thing I can think of is that a wifi-emitting device that powered with battery (eg mobile phones and portable computers) will immediately get the benefit.

 

[figgus]

I will not go into it here because it could fill an entire lecture course, but it is obvious you have nothing more then a pedestrian understanding of electricity

....

generators would not work because there is not enough free electrons in the air to be coaxed into the copper cables by the magnetic fields created by the generators. As in, generators do not generate anything but a spinning magnetic field that coaxes electrons out of the air, it does not actually create electricity)

What? Electrons from the air? The magnetic field shoves electrons already in the wire through the wire, it doesn't grab them out of the air.

The amusing part is that you have the gall to bash someone else's understanding of the subject...

 

[figgus]

Yes it will. Every wireless signal has a limited number of listeners and a range based on where those listener are and how much power they're drawing from the signal. For example, you have an antenna, and 2 listeners in a straight line. The antenna is a 1W antenna and person a has a 500mW draw on that signal. The second person is only going to be able to draw the other 500mW and no more. If the first person increases his draw to 1W, that second person wouldn't even know a signal was being generated. TV, Radio, WiFi, etc don't have this problem (yet) because they are pumping out extra wattage to increase range. If people started running around drawing signals out of the air this will become a huge problem because it will severally decrease the intended range of the signal and hamper its target listeners.

Uhh, no. The signal emits to a point in space at a constant rate, decreasing exponentially at the square of the distance. The way to get a larger signal is a bigger antenna, thus covering more radiated "points" in space. The number of antennas is irrelevant, since it is the physical space itself that determines the recieved signal. Note that this does not account for blockage by a closer antenna, it assumes clear line of sight for everyone.

 

[Guest]

It is certainly "snake oil". Many years ago, when TV stationstarted transmitting on UHF, 1 electronic market outlet started selling the simple " Loop Antenna ".

The Demo at the Electronics Centre produced SUPER reception of the TV Signal - the shop owners even REMOVER the back cover ot the TV sets - to show the didnt modify the TV sets.

In reality - they had a UHF antenna on the roof top and put 2 boaster TV Antenna amplifiers Coaxial cable and connected it to another UHF antenna INSIDE the shop.

No one knew about it because the shop also sell UHF TV antenna that were on display in the shop.

The " Loop Antenna " cost only 50 cents to produce but was sold at $15.00. HUGH Profit.

I was skeptical and knew that in reality, it CANT work. There must be some hiden thing in it.

ALL the shops were in the BASEMENT of a shopping complex !

Another " Snake oil " was the Cellular antenna re-transmitter - 1 cell antenna stuck on the glass outside your car, another cell antenna stuck INSIDE you car next to the outside antenna.

It claimed to "Improve" your cell signal by re-transmitting the Cell signal from outside.

Total failure after some iDiots bought them from manufacturers and failed to sell them.

 

[WheelsOfConfusion]

[citation][nom]dawolf74[/nom]@ Eric and Wheels
I will refer you to basic texts on electronics and electricity.There are ways to take a charge and use it to create bigger charges.[/quote]
You cannot just take a certain wattage in and put out a bigger wattage without using up a store of power from another source, that would violate the conservation of energy. You may be able to store and build up a charge over time, but you are still confined to the amount of power going into the system.

With EM coming off an antenna (which, in 802.11, is capped at 1 Watt MAX), the energy is dispersed in several directions at once, and as it moves out to cover a larger volume of space the power at any given point in space drops off sharply.

By your logic, generators would not work because there is not enough free electrons in the air to be coaxed into the copper cables by the magnetic fields created by the generators.

What the Hell are you talking about? Electrons stay (hopefully) within the wiring while FIELDS OF ELECTROMAGNETIC FORCE go through the air. Generators do not take electrons "from the air," it's the electrons present IN THE WIRING that get moved through the circuit! This happens to work because the electrons in a metal (like coppery wire) are particularly free to move from atom to atom, hence the property of metals being generally good conductors. If electrons were actually being stripped from the air itself the oxygen would be ionized, O2 would become unstable and subsequently turn into toxic Ozone (O3) and nobody would be able to work at power plants ever.

As in, generators do not generate anything but a spinning magnetic field that coaxes electrons out of the air, it does not actually create electricity)

If you define "electricity" as a flow of electric charge like most SANE people do, then yes it does create electricity. The electrons are moved in the form of charge as the magnetic field pulls them around and pushes them through a conducting medium (air can conduct electricity, but does this so poorly that it's generally an insulator unless you overcome the resistance with very high voltages). Magnetic fields, not electrons, are what move "through the air," or at least in relation to the conductor. In a generator, the wires move relative to the magnetic field and so induce a current. In a radio antenna, the electromagnetic field of the radio waves induces a current in the antenna.

I find that one of the most misunderstood physics by anyone is electricity and magnetic fields.

"No no no, the Earth actually stands still while the Sun goes about it in a big circle! I find that this is one of the most misunderstood aspects of physic!"

 

[doc70]

has anyone seen the charger in the process of re-charging itself from Wi-Fi? Didn't think so...

 

[taltamir]

The coolest part about it, is that this energy recycling.
The wifi transmitter sends a radio signal (which uses energy) in all directions. you harvest the little bit that hits you..

I wonder if having too many of those will lower the RANGE of wireless devices and/or increase their power consumption. (ex, if there are people with this in their battery between me and the transmitter)

 

[Memoscorp]

I gotta have this.

 

[Guest]

I can't believe you'd be able to get enough energy from wi-fi signals to recharge a battery. The energy density just isn't there. You'd do better trying to get power via induction from the AC current in the walls. I call BS.