Charger gets power from WiFi [please be true] [updated: man says it's not]

by Ben Smith on 23rd February 2010

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I was amazed when I saw this… it’s almost certainly too good to be true, but see the video after the break… US consumer-electronics giant RCA have created a box of tricks that sucks power out of the air driven by WiFi signals.

The cigarette-packet-sized gizmo plugs in to devices to provide a ‘free’ trickle charge, with the technology due soon built into batteries that will replace manufacturers’ originals (at about the same cost as the original).

According to OhGizmo:

on the CES floor, they were able to charge a BlackBerry from 30% to full in about 90 minutes, using nothing but ambient WiFi signals as a power source.

Now, I appreciate the power isn’t actually free… someone’s paying to power those WiFi hotspots… but given many of us spend most of our time blanketed in WiFi coverage this could be a great way to passively top-up your mobile devices as you move around. The external plug-in unit will be available this summer for around $40.

I really hope this works as promised… it certainly has a ring of ‘too good to be true and there’s a few doubters in the original post comments.

Source & Image Credit: OhGizmo!

Update: Similar to the original post a number of people are pointing out the physics doesn’t stack-up… This post from EEVblog’s David Jones says it all quite eloquently:

So… could it be true? And if not why has someone with the right to use the RCA name done this?

  • http://www.facebook.com/profile.php?id=707801289 facebook-707801289

    It is a little early for things like this – 1st of April is not for over a month….

    Just consider the variables in the equation here:

    – The maximum transmitted power from a standard WiFi AP is 100mW (many operate at less than this)
    – Even when in close proximity to the AP (1-2 metres) the energy transferred from the AP to the 'charger' is going to be tiny (we are talking microwatts)

    As Scotty used to say in Star Trek; “Cap'n, yae cannae beat the Laws of Physics”

  • http://www.jonathanmacdonald.com jMac

    Link here – http://www.youtube.com/watch?v=BV0AVe3-ROY hopefully it will be deemed as valid as the EEV opinion.

  • http://www.jonathanmacdonald.com jMac

    Link here – http://www.youtube.com/watch?v=BV0AVe3-ROY hopefully it will be deemed as valid as the EEV opinion.

  • http://shkspr.mobi/ TerenceEden

    There are two possibilities.1) RCA are going to win a Nobel Prize for fundamentally changing the way we understand physics. They will be seen as saviours of the energy crisis and will become billionaires. They have chosen to announce this paradigm shift which will revolutionise the world as a $40 device at a trade show.2) It's a con. Pure snake oil. Utter rubbish.Which do you think is more likely?For those who don't want to read the comments on the linked post, let me explain with as little mathematics as possible.A WiFi access point can transmit a maximum of 0.1W.A WiFi access point radiates energy in a sphere – it does not direct the signal.A WiFi access point does not transmit all the time.A typical USB charger supplies about 4.4 volts at 100 milli Amps. That's about 0.44 Watts.So, this magical devices would need to absorb ALL of the power produced by a WiFi access point with 100% efficiency with the WiFi transmitting ALL the time in order to get a quarter of the needed power.And that's the best case scenario. And it's impossible.Ever noticed how the futher away you get from WiFi, the lower the signal is? That's because the power decreases the further away you are.Don't forget, the WiFi isn't transmitting towards you, it's transmitting in a great big sphere. So the total amount of power you receive from a WiFi AP is minuscule. This is why it doesn't fry your head.If you want to go into the physics, I'd be happy to. This is a nice idea – pick up lost power – but as Scotty says “You canna change the laws of physics!”

  • http://shkspr.mobi/ TerenceEden

    There are two possibilities.
    1) RCA are going to win a Nobel Prize for fundamentally changing the way we understand physics. They will be seen as saviours of the energy crisis and will become billionaires. They have chosen to announce this paradigm shift which will revolutionise the world as a $40 device at a trade show.

    2) It's a con. Pure snake oil. Utter rubbish.

    Which do you think is more likely?

    For those who don't want to read the comments on the linked post, let me explain with as little mathematics as possible.

    A WiFi access point can transmit a maximum of 0.1W.
    A WiFi access point radiates energy in a sphere – it does not direct the signal.
    A WiFi access point does not transmit all the time.

    A typical USB charger supplies about 4.4 volts at 100 milli Amps. That's about 0.44 Watts.

    So, this magical devices would need to absorb ALL of the power produced by a WiFi access point with 100% efficiency with the WiFi transmitting ALL the time in order to get a quarter of the needed power.

    And that's the best case scenario. And it's impossible.

    Ever noticed how the futher away you get from WiFi, the lower the signal is? That's because the power decreases the further away you are.

    Don't forget, the WiFi isn't transmitting towards you, it's transmitting in a great big sphere. So the total amount of power you receive from a WiFi AP is minuscule. This is why it doesn't fry your head.

    If you want to go into the physics, I'd be happy to. This is a nice idea – pick up lost power – but as Scotty says “You canna change the laws of physics!”

  • http://shkspr.mobi/ TerenceEden

    YouTube replies are too short, so I'll comment here.

    I can turn lead into gold.
    I can transmit information faster than the speed of light.
    I can cram more information into a signal than Shannon's law will allow for.

    I don't doubt that someone, somewhen, will be able to do these things. But it requires such a jump in our fundamental understanding to the laws of the universe that it's not even worth considering now.

    “The phone will replace TV” would have been an idiotic statement twenty years ago – but today it's (almost) a reality.

    The key difference is there is nothing in our understanding of the universe stopping phones being TV. Nothing to stop wristwatches replacing phones. Nothing to stop wristwatches transmitting holographic video.

    But there is something stopping perpetual motion. There is something stopping minuscule amounts of waste energy being collected with 100% efficiency and being able to counter the self-discharge rate of current batteries.

    So, do you think that this company has come up with a brand new battery with no self-discharge, an energy collector as efficient as a Dyson sphere and a way to collect more energy than is being produced? If so, why are they releasing a $40 gizmo at MWC rather than collecting their Nobel Prizes?

    Don't get me wrong – there are small companies revolutionising *business* every day. But there aren't any revolutionising physics.

  • http://shkspr.mobi/ TerenceEden

    YouTube replies are too short, so I'll comment here.I can turn lead into gold.I can transmit information faster than the speed of light.I can cram more information into a signal than Shannon's law will allow for.I don't doubt that someone, somewhen, will be able to do these things. But it requires such a jump in our fundamental understanding to the laws of the universe that it's not even worth considering now.”The phone will replace TV” would have been an idiotic statement twenty years ago – but today it's (almost) a reality. The key difference is there is nothing in our understanding of the universe stopping phones being TV. Nothing to stop wristwatches replacing phones. Nothing to stop wristwatches transmitting holographic video.But there is something stopping perpetual motion. There is something stopping minuscule amounts of waste energy being collected with 100% efficiency and being able to counter the self-discharge rate of current batteries.So, do you think that this company has come up with a brand new battery with no self-discharge, an energy collector as efficient as a Dyson sphere and a way to collect more energy than is being produced? If so, why are they releasing a $40 gizmo at MWC rather than collecting their Nobel Prizes?Don't get me wrong – there are small companies revolutionising *business* every day. But there aren't any revolutionising physics.

  • http://www.twitter.com/martyndavies martyndavies

    Radiation also follows an inverse square law, so the available power falls with the square of the distance between you and the transmitter. In other words, if you thought 8 years was a long time to charge your phone when you were 1m away, just wait until you get 2m away.

  • http://www.twitter.com/martyndavies martyndavies

    Radiation also follows an inverse square law, so the available power falls with the square of the distance between you and the transmitter. In other words, if you thought 8 years was a long time to charge your phone when you were 1m away, just wait until you get 2m away.

  • illusionado

    I'm sure this will cost a lot compare to the years of being patient on plugging/unplugging the charged devices.

  • illusionado

    I'm sure this will cost a lot compare to the years of being patient on plugging/unplugging the charged devices.

  • http://www.facebook.com/profile.php?id=707801289 Anonymous

    “Wizzbang fractal antenna manufactured by nude virgins…”

    What a star David Jones is!

  • http://www.facebook.com/profile.php?id=707801289 facebook-707801289

    “Wizzbang fractal antenna manufactured by nude virgins…”What a star David Jones is!

  • http://www.facebook.com/profile.php?id=707801289 facebook-707801289

    “Wizzbang fractal antenna manufactured by nude virgins…”

    What a star David Jones is!

  • Mike42

    The EEVBlog reply is classic. The mobile industry needs guys like David Jones in every boardroom. With free licence to shout “BULLSHIT” at every half-arsed idea that gets thrown up.

    I was going to record a video reply to Jonathan citing microwave power density stuff, Isotropic radiation patterns, power densities, etc, but then watched David sum it all up much better than I ever could (plus he has a snazzy whiteboard and loads of geek kit to lend him cred. Best I could do these days is a table lamp and a few old Nokias ;-)

    And who’s behind this? From RCA’s own website: “The RCA brand is licensed to third parties for televisions, car stereo equipment, microwaves and accessories”. In other words, I could be. Or the dodgy bloke down the high street flogging anti-mobile radiation stickers for your phone.

  • Mike42

    The EEVBlog reply is classic. The mobile industry needs guys like David Jones in every boardroom. With free licence to shout “BULLSHIT” at every half-arsed idea that gets thrown up.I was going to record a video reply to Jonathan citing microwave power density stuff, Isotropic radiation patterns, power densities, etc, but then watched David sum it all up much better than I ever could (plus he has a snazzy whiteboard and loads of geek kit to lend him cred. Best I could do these days is a table lamp and a few old Nokias ;-) And who's behind this? From RCA's own website: “The RCA brand is licensed to third parties for televisions, car stereo equipment, microwaves and accessories”. In other words, I could be. Or the dodgy bloke down the high street flogging anti-mobile radiation stickers for your phone.

  • Mike42

    The EEVBlog reply is classic. The mobile industry needs guys like David Jones in every boardroom. With free licence to shout “BULLSHIT” at every half-arsed idea that gets thrown up.

    I was going to record a video reply to Jonathan citing microwave power density stuff, Isotropic radiation patterns, power densities, etc, but then watched David sum it all up much better than I ever could (plus he has a snazzy whiteboard and loads of geek kit to lend him cred. Best I could do these days is a table lamp and a few old Nokias ;-)

    And who's behind this? From RCA's own website: “The RCA brand is licensed to third parties for televisions, car stereo equipment, microwaves and accessories”. In other words, I could be. Or the dodgy bloke down the high street flogging anti-mobile radiation stickers for your phone.

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