Information Technology Reference
In-Depth Information
Figure 1.5
Battery indicator
Current battery charge
To show or hide the percentage next to the battery indicator, go to
Settings > General and tap the Battery Percentage switch.
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 demand-
ing on the processor and will eat up power faster than reading a book in
iBooks. 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. 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.
