The iPad includes a non-removable lithium-polymer battery that provides up to 10 hours of use on a single charge. In fact, Apple claims that 10 hours of video playback, surfing the Web using Wi-Fi, or listening to music are possible. You can check the state of the battery by looking at the indicator in the upper-right corner of the screen.
Note: To show or hide the percentage next to the battery indicator, go to Settings > General and tap the Battery Percentage switch.
As the battery nears depletion, warning messages appear when 20 percent and 10 percent of the power remains. After that, the iPad becomes unresponsive and needs to be charged to function again.
To replenish the battery’s charge, plug the iPad’s sync cable into the included power adapter (charging takes about four hours if the battery is nearly spent).
You can also plug the sync cable into your computer to sync and recharge, but there’s a catch: Your computer’s USB port may not have the oomph to do it. If that’s the case, you’ll see “Not Charging” in the power indicator at the upper-right corner of the screen.
The specifications for running power over USB call for at least 5V (volts), but the iPad requires more than that. Some computers, such as recent Apple laptops and desktops, can optionally provide as much as 12V when a device that requires it is connected. In that case, the iPad will charge, but more slowly than when connected to the power adapter.
Advantage of charging your iPad Using USB Port:
The upside is that when connected to a low-power USB port, the battery does not deplete; in fact, it will trickle-charge slowly when the iPad is asleep, and keep a steady level when it’s awake.
Steps To Conserve battery life on iPad
You can take steps to make the most of the battery’s charge. No need to be slavish about these, but you’ll definitely want to implement them when you get a low battery notice:
- Turn down the screen brightness.
- Turn off Wi-Fi if you’re not within range of a wireless network.
- Turn off Bluetooth if you’re not using it.
- Disable Push notifications.
- Disable 3G networking (provided you own the 3G model) if you’re not accessing data online.
Actual battery life depends on how you use the iPad, of course—playing a video game that makes extensive use of 3D graphics is more demanding on the processor and will eat up power faster than reading a book in iBooks.