If you’re having trouble getting a full day’s worth of battery life from your smartphone, a few tweaks in the settings menu can give you hours more use.
If you’re using an Android smartphone, open Settings. Under “Display,” you’ll find options for changing your screen’s brightness: the dimmer the better, for battery life. Also, set the “Screen timeout” to 1 or 2 minutes, so that it will dim automatically if you leave it untouched for that long. Under “Wireless & networks” you can turn off Wi-Fi and Bluetooth, and under “Accounts & sync” you can turn off “Background data,” which lets your apps access the Internet to check for new emails and things.
Keep in mind, if you turn off background data, this will disable your widgets like weather and stocks, and will keep you from being told when you’ve got a new email. If you want, though, you can change some of those widgets’ and apps’ settings manually, and tell them to update less often. This also saves precious megabytes on your data plan.
On an iPhone, launch Settings, then tap on “Wi-Fi” or “Brightness” to change the settings for each. Bluetooth can be found under “General,” and you can tell your iPhone to check for email less frequently under “Mail, Contacts, Calendars”. Apple has some other suggestions for you on their website, plus fixes for the iPad and iPod Touch’s battery life.