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My new Samsung SGS3 is equipped with Near Field Communication, which allows the phone to read a unique RFID code wirelessly from a nearby physical tag. The tag doesn't have any power source. Does constantly listening for an RFID tag drain my battery significantly?

I am trying to make a cost benefit decision about employing NFC. The cost is the battery consumption and benefit is the added NFC capability. I am also interested to learn more about how NFC and RFID work.

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I see my question was closed, probably because some editors don't consider a smart phone to be a computer. I disagree, a smart phone is a computer. – steampowered Jul 26 '12 at 2:49

closed as off topic by Diogo, Mike Fitzpatrick, 8088, Sathya♦ Jul 24 '12 at 4:15

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2 Answers

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There are two different modes. In passive mode, there is no energy consumed by the device that being read. In active mode, there is a small amount of current (less than 15 mA) that will be used.

Up to you if that amount is too much.

The way that it works is similar to the way that RFID works. In essence, there is a modulator/demodulator that turns the power from the reader into current that can power an integrated circuit, which controls a transmitter.

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Interesting. So the active mode would be the mode which drains the battery. It seems creating a field which powers another device's transmitter would consume lots of battery, but maybe my intuition is wrong. – steampowered Jul 23 '12 at 23:19
Not lots, just 15 mA (or less) – soandos Jul 23 '12 at 23:19
@steampowered: Only if you were generating such a field continuously, but there is no need to do that. You can just create the field for a fraction of a second. – David Schwartz Jul 24 '12 at 0:07
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No, it shouldn't drain battery much.

Although the tag gets it's power from the signal emitted by the samsung. because it's not over a great distance, and takes a very small amount of time, you should not see huge battery drain. Also typically nfc is not in use while the device is in standby mode.

Of course, your mileage may vary.

google for 'nfc battery drain'

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