15 minuten - 1 uur
My iPhone was shutting down when it still showed anywhere from 20 - 50% battery charge left. When I would put a charger on it, the dead battery icon appeared for a few seconds, then the Apple logo as it rebooted, and when it came back to life it would show the same amount of battery charge or more. Very frustrating. I tried all the usual "repairs" that I found on the internet; resetting, restoring, calibrating the battery...none of that nonsense worked. If your phone is shutting down prematurely, chances are it needs the battery replaced.
The repair went well. The hardest part for me was removing the battery. Pulling on the tab as some have suggested didn't work...it eventually broke. I was able to get a plastic pry tool under one corner of the battery and I pulled straight up using steady pressure. I was careful not to pry against something else in the phone for fear of breaking it.
Removing the top glass requires firm steady pressure also. I put the tip of my finger in the Lightning port opening to help hold the phone down while I pulled up on the suction cup. The battery lasts all day now, and it doesn't shut down prematurely anymore.