Scenario 2: iPhone with a fixable battery problem.
Some iPhone users have complained that battery life is poor on either new iPhone 4S phones or older phones upgraded to the iOS 5 release. It seems that sometimes this is fixable, and sometimes not. Symptoms include battery use faster than described above and sometimes a phone feeling warmer to the touch than normal when it's being used (phones normally get a tad warm when charging).
A tool such as System Status is useful as well. It can provide hints--if not outright proof--of a problem. For example, on the overview screen it shows CPU Usage:
A high CPU load indicates that applications are taxing the CPU, which might mean that one or more applications has a problem. The Processes tab doesn't show how much CPU is currently being used by a process, but does show the overall CPU time that each process has used. If an important or unknown (and non-system) application is using lots of CPU time, you might try killing the process to see if it solves your problems. To kill a running application, double-tap the home button to bring up a list of running applications, then tap-and-hold on an app to start it wiggling. Press the red "-" to kill the process.
Other theories abound as to the cause of short battery life and ways to solve the problem, ranging from turning off automatic time zone detection (Settings-> General -> Date & Time -> Set Automatically) to switching from a white iPhone to a black one (seriously). Any of those might work, but several people (including me) have solved their battery problems by following this procedure:
- Settings-> General-> Reset-> Reset Network Settings
- Perform a hard reboot. The steps depend on the iPhone version but on the iPhone 4S hold down the power button for more than 10 seconds.
It's not clear why this works, but it does seem to, at least some of the time. If it doesn't work then it's possible that a "clean restore" via iTunes might. To do this, first install the phone as new. Add apps, music, and other data just as you would a new phone. This is highly disruptive so think of it as a last resort and make sure you have backups of everything you need.