Why is iPhone battery percentage fluctuating at lower levels? My iPhone 4 (going on 19 months of love) has recently started having a bit of an issue knowing the percentage of its battery it has remaining.  I will be using it and it will jump from 31% to 19% and pop up that annoying "Low Battery" notification.  A few moments after I dismiss it, the percentage jumps back up to 27%. This happens at least ten times, reliably, before it starts hitting 11% and then I know it was "real" and it needs charging soon. This feels like a NiCad issue… I know we've advanced past those days.

So my question is: how can I force a calibration of the percentage counter on iPhone 4?  Alternatively, and I don't know that I would like this even if it is possible (I doubt it is), can I disable the "Low Battery" notification?  It is excessively annoying when it pops up ten times over the course of thirty minutes.
To recalibrate your iPhones battery, you should:


Use the iPhone until it shuts off due to low battery.
Charge it, without interruptions, to full charge (100%).
Reset the iPhone by Holding Home and the Power buttons at the same time. Ignore the Slide to Power off,  and let the iPhone restart itself.


And for the notifications, as far as I know, no such thing can be achieved without jailbreaking. Cydia's app LowPowerBanner, for instance, should do the trick, though.