There is a quick and easy battery life test built into your device, if you do a little bit of math — the Usage and Standby times. Head on over to Settings > General > Usage and check out your times.
Your Usage time is how long you have actually used your device, and the Standby time is how long your device has been dormant in-between the times you’ve used it plus your Usage time. A better name for Standby time would be “Total Time since unplugged.” The key to look for is that your Usage time should be significantly lower than your Standby time, unless you have been using your device every single second you’ve had it unplugged. If this is not the case and your Usage time is exactly equal to your Standby time, you have a severe problem. The bottom line is that your Usage time should be accurate to how much you’ve used it since you took it off the charger.
So here’s the test: write down your usage and standby time, press the sleep/wake button (or lock button, as some call it) to put the device to sleep, and set the device down for five minutes. When you come back, take note of the change in time. If your device is sleeping properly, then the Standby time should have increased by five minutes and your Usage time by <1 minute . If your Usage time rises by more than one minute, you have a drain problem. Something is keeping your device from sleeping properly, significantly shortening the time it will last.