Coffeehouse Thread

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dose NFC drains battery?

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  • magicalclick

    Just wondering, thanks.

    Leaving WM on 5/2018 if no apps, no dedicated billboards where I drive, no Store name.
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  • DeathBy​VisualStudio

    Doesn't NFC stand for "No F'ing Current"? If so then I think not. Wink

    If we all believed in unicorns and fairies the world would be a better place.
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  • spivonious

    I believe NFC is only powered up when transferring, like the door badges we use at work. So I'd guess it's not going to drain the battery unless you're constantly transferring stuff, and then no more than bluetooth or wifi.

  • magicalclick

    But, what about signal polling? Like wouldn't they periodically polling for requests? Or is this different than Bluetooth and Wifi? Like they use some kind of magnet to physically move something in the sensor and mechanically trigger it? Thus, it operate at absolute zero battery?

     

    Leaving WM on 5/2018 if no apps, no dedicated billboards where I drive, no Store name.
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  • Blue Ink

    , magicalclick wrote

    But, what about signal polling? Like wouldn't they periodically polling for requests? Or is this different than Bluetooth and Wifi? Like they use some kind of magnet to physically move something in the sensor and mechanically trigger it? Thus, it operate at absolute zero battery?

    Yes. The device initiating the communication emits an electromagnetic field that powers up some circuitry in the receiving device (like a wireless charger does, for instance). That's enough to signal the other party that it should turn on its radio.

  • JohnAskew

    Near field communication (NFC) is a set of standards for smartphones and similar devices to establish radio communication with each other by touching them together or bringing them into close proximity, usually no more than a few centimetres. Present and anticipated applications include contactless transactions, data exchange, and simplified setup of more complex communications such as Wi-Fi. Communication is also possible between an NFC device and an unpowered NFC chip, called a "tag".

    http://en.wikipedia.org/wiki/Near_Field_Communication

     

    Aren't you supposed to put one of those clear plastic covers over the phone before touching?

  • magicalclick

    @Blue Ink:

    That's cool, that's what I want. Because no matter how little battery Bluetooth and WiFi polls the battery, it still count over a long day.

    Leaving WM on 5/2018 if no apps, no dedicated billboards where I drive, no Store name.
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  • CoachDavid

    The NFC in phones is powered.  NFC has a non powered mode, but in order for a device like a phone to read it, the magnetic field from the phone powers the passive NFC devices.

     

  • JoshRoss

    I can has cheezburger?

  • JoshRoss

    But seriously, yes. Just turn it off. It's just one more thing that you will never use.

  • Ion Todirel

    , JoshRoss wrote

    But seriously, yes. Just turn it off. It's just one more thing that you will never use.

    NFC is the future, turn it off you cannot Smiley

  • blowdart

    , Ion Todirel wrote

    *snip*NFC is the future, turn it off you cannot Smiley

    I did Tongue Out

  • davewill

    @Ion Todirel: Hopefully all will be able to turn off.  What other means would there be to keep someone from giving me something dirty with a little pocket bump in a crowd?

  • joebagodoe

    A typical NFC transceiver draws ~50mA of current when powered up. For reference, this equates to around 25% of the total consumption of a typical smartphone with the screen powered on. 

    Left unchecked, this could have noticeable, adverse effect on battery life. 

    However, there are optimization techniques that can significantly reduce the effects of NFC on battery life. For instance, the Android NFC subsystem could carry out the following:

    • Intelligent polling - Android doesn't leave the NFC transceiver running at all times, instead it polls for tags at a rate around ~10Hz to conserve battery life. Maybe a feature in future ROMs would be the ability to change the polling frequency down to 1Hz.
    • Polling disabled on screen lock - when the screen is locked Android ceases to poll for tags, however card emulation continues (this is how Google Wallet functions even when the screen is locked) .
    • Screen off = NFC off - the NFC radio is powered down when the screen is locked.
  • joebagodoe
  • DeathBy​VisualStudio

    I use NFC all of the time to bump my kids to-dos in Any.Do. I also share web sites and sometimes pictures. It's been pretty useful to me but then again I'm on Android.

    WiFi direct is pretty cool too. I use it to create a local LAN so the boy & I can play some LAN based team games while sitting in the car waiting for my daughter.

    I have the Galaxy Note II and they both have Galaxy Nexuses. We leave all of the wireless stuff on all day long and never come up short on battery at the end of the day. Bluetooth, WiFi, NFC, etc.

    If we all believed in unicorns and fairies the world would be a better place.
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