If the battery life on your iOS device could be better, here's a few general tips that may help. The following list was compiled with iOS 7/7.1 in mind, but may prove useful for older (or even future) versions of the operating system.
Turn off WiFi, Bluetooth, GPS, AirDrop, Location, and other services when not in use
Set the display to the minimum acceptable brightness, and consider turning off auto brightness
Use a white background to save a little power on the LCD display
Turn off Background App Refresh
Consider using a fetch schedule instead of push for email accounts
Disable automatic updates for apps
Disable indexing for unneeded apps in Spotlight Search
In the accessibility settings, toggle Reduce Motion to tone down the system animations
If your battery life has taken a dive recently, check out the most recently installed apps & see if uninstalling them helps
Consider a settings refresh, under Settings>General>Reset>Reset all settings. This will erase any stored WiFi passwords, but can help if settings that reduce battery life have been toggled on by mistake
If you have no joy with all of the above, try a restore through iTunes
If this helped, or you have any additional suggestions, please do sing out!
I wanted to contribute my very own list of tips to reduce data usage and optimise battery life, as written by an ex iOS technical advisor. Admittedly, it's an exhaustive list and thus kind of lengthy but I've had good feedback from my customers so I thought it could be helpful.
Check for data hungry apps
Go to Settings>Cellular and scroll down to "Use cellular data for:" this will show a list of the top data users and a MB or GB usage amount below the app name. You can reset this each month to keep an eye on the top data users.
Close programs using multitask
Pressing your home button twice will open the multitasking view, this view shows all programs that are currently running in the background/saved in the cache. To close a program place your finger in the middle of the screen and then drag/swipe the page-view towards the top of the screen – it should slide off the screen which means you have successfully closed it. Clear this out every couple of days.
Powercycle your device every couple of weeks
Just like your PC your iOS device needs to be restarted every now and then to optimise performance and battery life. Powercycling is just a fancy word for "turn it off and back on again." This will clear the iPad's cache and background programs which can often make a huge difference to performance and battery life.
Assess and change your charging habits
It is important to let your iOS device's battery run right down and then charge it back to 100% uninterrupted every now and again. If you have a habit of constantly topping up the battery whenever it drops below a certain percentage this can be bad for your device's battery soit's good to use the battery right up and then charge it back to full completely before using it again.
Turn off Location Services
Go to Settings>Privacy>Location Services and switch off
Location services can be handy if you use Google Maps a lot but ultimately it is unnecessary and uses a lot of data if it is running all the time.
Background App Refresh
Settings>General>Background App Refresh
Turning this off will help reduce data usage and save your battery life. The setting makes sure all apps that are running have up to date location and internet data and like location services it is ultimately unnecessary as whenever you open an app it will be refreshed anyway.
Settings>iTunes and App Store >Automatic Updates
Turning this off means you can decide when to update your apps, rather than the apps updating in the background without your knowledge.
iCloud automatic backup
Settings>General>Storage and Backups>Automatic Backups
Turning off this means you will have to remember to backup manually using iTunes or iCloud if backing up regularly is something that is important to you. To back up manually via iCloud: Settings>General>Storage and Backups>Back Up Now
Delete app caches
Find the app under Settings and then select “Delete Cache” or “Delete History” or “Delete Cookies and Data”
You can delete the temporary files for each app. This doesn’t specifically increase battery life or reduce data usage but it will make your iPhone run more smoothly. For third-party apps, i.e. apps you’ve downloaded yourself, the option to delete the cache may not be present as the developer of the app may have chose not to include it in the app Settings.
Reduce Motion Effects
Open Settings, select General, then Accessibility, then tap Reduce Motion and switch on.
Again this will not reduce data usage but it will increase battery life and performance of your device.
Turn off automatic mail fetch
Open Settings>Mail, Contacts, Calendars>Fetch New Data.
This will take you to a list that shows all email accounts on the iPhone (Gmail, YahooMail etc) Select your email account and select “Fetch”. Set the Fetch interval to 15+ minutes.
If the fetch interval is set to automatic this means your iPhone is contacting your email server every few minutes to check for new mail which uses a lot of CPU and battery life too. If it is important that you get your emails updating constantly set the option to Push, rather than Fetch. This means that your mail server will “push” the new mail to your iPhone, rather than your iPhone having to check the server and “fetch” the new mail.
I hope these tips help! If you continue to have issues you can call 0800 MY APPLE or call through to 777 or 888 for business customers.