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Why is the NFC in the Galaxy Nexus embedded in the battery?

Wouldn't it make more sense to separate the two things? Is there any hardware advantage of being this way?

Disadvantages I can see several, like replacing the battery with another, without NFC...

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2 Answers 2

up vote 21 down vote accepted

The NFC feature does not sit in the battery, only the antenna does.

NFC consists of:

  • an integrated chip (soldered onto the logic board)
  • an NFC Antenna that needs free view to the phone's back side
    (antenna signals from the sticker on the back of the battery only need to pass the back cover)

If you look at the antenna you'll notice how big it is. It's basically just a coil with 4 windings, see ifixit's teardown. NFC allows for passive devices (Credit cards and such) which need to be fed energy from an active device through the antenna. Some engineer decided its best fit would be as a sticker on the battery.

There's only 2 positions where you can place it:

  • Back of the battery
  • Inner side of the battery cover (like with the Nexus S)

My guess is this: By placing it on the battery, the expensive and big 2-point connector (as with the Nexus S) could be merged together with the battery contacts to make it cheaper (and/or maybe more robust).

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No way to use a NFCless battery and still have NFC features? (without hardware hacking) –  NeTeInStEiN Jul 9 '12 at 13:10
2  
Is this your sole problem (you have a replacement without a battery I guess)? Sadly, you have to do some hardware hacking, I guess. At least peeling off the antenna sticker off the dead battery and subsequently resoldering it onto the new (cheap) one. –  ce4 Jul 9 '12 at 13:21

The NFC circuitry itself is in the phone, but the antenna is in the battery. This is due to the layout of the phone. Since the range of NFC is very small, the antenna is placed on the outer side of the battery to increase the range as much as possible.

Yes, the downside of this is that replacement batteries need to be NFC-enabled, but it's a small price to pay for a significant improvement in the functionality of NFC.

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But does that imply that without an NFC battery it would also be possible to use it? –  NeTeInStEiN Jul 9 '12 at 11:07
    
No, the antenna is necessary because of the limited range. Theoretically it's possible, but the range is less than millimeters. –  onik Jul 9 '12 at 11:13

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