Here's an overview of how to improve the battery life of the iPhone 4S and why it doesn't have as good battery life as previous generations of iPhone.
Let's start with why it doesn't have as good of a battery compared to say the iPhone 4.
- Dual-core processor (clocked at 800Mhz)
- Same battery as the iPhone 4, despite the more powerful processor found in the 4S
- Siri, along with more reliance on Location Services based on user usage of services
- Better data speeds, 3G radios were upgraded to include HSPA+ support, possibly causing battery loss
- iOS 5, including iCloud syncing and other various new features that are more taxing to the SoC
There may be other reasons why, but those are the basic reasons why the battery life of the 4S may not be as good compared to the previous iPhone.
Now, lets look at how you can increase your iPhone 4S's battery life.
- Disable Location Services in Settings, this removes functionality in many apps such as Siri, Maps, and Weather
- Decrease brightness, the screen draws a ton of power, decrease the brightness in Settings
- Turn off 3G service when connected to WiFi, go to Settings, and Usage (iirc)
- Turn off WiFi when you are on the road to prevent the iPhone from searching for possible networks
- Turn on Airplane Mode at night to turn off all networking
- Turn off Push email, and set it to Fetch. Fetching manually conserves the most battery life
- Cancel app processes after you're done by double tapping on the Home Button, holding down on one of the apps in the multitasking tray until they have red "-" signs on the top left corner. Close the most recent apps, probably five or so
- Enable Restrictions, and restrict Ping (applies if you listen to music on your phone)
- Try to keep your iPhone on an area where heat can dissipate to increase efficiency.
I do not recommend disabling iCloud, as it enables useful features such as Backup (while plugged in and in sleep mode), and Find My iPhone, a useful feature if you ever lose your iPhone.
HuskieN