Substantial battery drain on the iPhone 4S, reported earlier, might be because of a bug in the way iOS 5 handles location services. Switching on “Setting Time Zone,” an option buried deep in the Settings app, might result in location services being called too frequently resulting in the excessive battery drainage.
Location services, as we all know, if not used efficiently can result in huge battery consumption reducing device standby time. Background location calls are even riskier, since they can keep happening even when your phone is in sleep mode.
“Setting Time Zone”, it seems polls location services even when the user hasn’t moved a lot. The way background location services API works is, if the user moves a set distance, say 10 km, then iOS sends a notification to the app after which the app can take required action. Since “Setting Time Zone” is an internal service, its implementation isn’t known, but switching off the option seems to do the trick for a lot of users.
So you can switch off the “Setting Time Zone” preference (Settings>Location Services>System Services) to see if it improves your iPhone 4S’ battery life. You anyway don’t need this option turned on unless you travel between different time zones.
If this doesn’t work, try going through tips to improve the battery life of iOS 5 devices and see if that helps.
Apple is reportedly contacting iPhone 4S users who are reporting extremely poor battery life to investigate the problem. However, Apple hasn’t yet made any formal statement on the issue.
Most likely Apple will deliver a minor update very soon (iOS 5.0.1), which would resolve the bug. And with OTA (over-the-air) delta software updates, upgrading iOS no longer means that you would have to download a file weighing in at 600MB just to solve a minor bug, albeit with huge consequences.
Since this an issue with software rather than hardware, it is possible that other iOS 5 devices may also be vulnerable to the same problem. We suggest the other iOS device users also take the same measures if they observe abnormal battery consumption.