How to view iphone 3GS Usage Stats

“Battery life” means the time your iPhone will run before it must be recharged. “Battery lifespan” means the total amount of time your battery will last before it must be replaced.

Usage
Show battery percentage:

Tap Usage and turn Battery Percentage on to display the percentage of battery charge next to the battery icon in the upper-right corner of iPhone (iPhone 3GS only).
See your usage statistics:

Choose Usage. There, you can see:

* Usage—Amount of time iPhone has been awake and in use since the last full charge. iPhone is awake whenever you’re using it—including making or receiving phone calls, using email, sending or receiving text messages, listening to music, browsing the web, or using any other iPhone features. iPhone is also awake while performing background tasks such as automatically checking for and retrieving email messages.
* Standby—Amount of time iPhone has been powered on since its last full charge, including the time iPhone has been asleep.
* Current period call time and lifetime call time.
* Amount of data sent and received over the cellular data network.

Reset your usage statistics:

Tap Usage and tap Reset Statistics to clear the data and cumulative time statistics. The statistics for the amount of time iPhone has been unlocked and in standby mode aren’t reset.