How to Charge Your iPhone Battery
Like all battery-powered gadgets, your iPhone is useless with an uncharged battery. The good news is that iPhone recharges in less than an hour, and you can charge the battery in several ways.
The battery icon in the status bar indicates roughly how much battery power you have. If you want to see a specific percentage, tap Settings→General→Usage and turn on the Battery Percentage switch toward the bottom of the screen.
How to plug your iPhone into the USB charger
Your iPhone comes with a USB connection cable and a USB power adapter. To charge the battery, plug the dock connector into the dock port at the base of your iPhone. Plug the USB end into the USB power adapter and plug the power adapter into an electrical outlet. iPhone beeps, which lets you know it's actively charging.
How to charge with your iPhone with your Mac or PC’s USB port
When you connect your iPhone to a USB port on your computer to sync or transfer photos, the battery automatically begins taking a charge. If your computer is turned off or is sleeping, your iPhone battery may drain instead of charge, so make sure your computer is on whenever you connect your iPhone to it.
Although plugging your iPhone into any recent or new Mac can charge your iPhone, the same isn't necessarily true for recent or new Windows desktop and notebook computers or older Macs. Apple explains that's because the USB ports on certain of those models don't pass through enough wattage to charge your iPhone.
If connecting your iPhone to your USB port doesn't yield a charge — you know it's charging because it beeps and there's a lightning bolt next to the battery in the status bar — try plugging into a port dock on a powered USB hub. If that doesn't work, you'll have to plug into a charger to charge your iPhone.
If iPhone's battery charge drops very low or runs down completely, your iPhone automatically shuts itself off. To bring your iPhone back to life, you must attach the USB cable to a power source (your computer or an electrical outlet).
When your iPhone shuts itself off because the battery charge is too low or nearly empty, you won't be able to use your iPhone until the battery reaches a minimal charge level. Usually you only have to wait a few minutes before your iPhone turns itself on again.
To preserve the overall life, you should cycle the battery on a monthly basis. Cycling is letting the battery completely discharge and then charging it fully.
How to change the iPhone battery
If you keep your iPhone for many years, sooner or later, you'll need to replace the battery. Despite our DIY (do-it-yourself) world, you can't replace the battery yourself. You have to send it in to the Battery Replacement Program.
For $85 (at the time of publication), you send your iPhone to Apple or take it to an Apple store, the battery is replaced, and Apple takes care of disposing of the old one. This service is covered if your iPhone is still under the one year warranty or you extended the warranty to two years with the AppleCare protection plan.
Technically, you should get about eight hours of talk time on an iPhone 5 on the 3G network. Realistically, if you play games and go on the Internet, you probably get less. Here are some tips for keeping the battery charged longer and for maintaining long battery life.
Turn Off Location Services: Go to Settings→Privacy→Location Services. (Remember though that the apps that use it do so only when you’re using them.)
Turn Off Wi-Fi: If you have Wi-Fi turned on and there’s no Wi-Fi network, your iPhone keeps searching and searching and consuming battery power. To turn off Wi-Fi, tap Settings→Wi-Fi→Off or swipe up from the bottom of the screen to open the Control Center and tap the white Wi-Fi button so it’s dimmed.
Turn Off 4G: If 4G isn’t available where you are or you don’t need to access the 4G network, turn it off. Tap Settings→ Cellular→Enable 4G Off.
Turn Off Siri: If you don’t need Siri’s assistance, may as well send her out to lunch since she’s a power hog. Tap Settings→General→Siri Off.
Turn On Airplane Mode: If you happen to be out of your network range, your iPhone consumes a lot of battery power as it continually searches for the cellular network. Eventually the words No Service appear instead of the carrier name and your iPhone settles down and stops searching.
Consider putting your iPhone in Airplane mode: Tap Settings→Airplane Mode On or swipe up from the bottom of the screen to open the Control Center and tap the Airplane Mode button.
Use Fetch Instead of Push: Rather than having your iPhone constantly check for new information with Push, you can set your iPhone to sync with whichever cloud service you use at set time intervals, or sync manually. Tap Settings→Mail, Contacts, Calendars→Fetch New Data→Push Off.
Use Auto-Brightness: Dimming your screen also improves the length of a charge. The ambient light sensor dims or brightens your screen based on the light it senses. You can turn the automatic adjustment on by going to Settings→Wallpapers & Brightness→Auto-Brightness On.
Bluetooth: Tap Settings→Bluetooth→Off if you don’t have any Bluetooth devices connected and don’t plan to use any for a while or swipe up from the bottom of the screen to open the Control Center and tap the Bluetooth button so it’s dimmed.
Cellular Data: Tap Settings→Cellular→Cellular Data Off. You can still use the phone and Wi-Fi connection.