Apple MacBook Pro (17-inch, Mid 2009) - Manual (Page 30)

30 Chapter 2 Life with Your MacBook Pro
Using the MacBook Pro Battery
When the MagSafe power adapter isn’t connected, your MacBook Pro draws power
from its built-in battery. The length of time that you can run your MacBook Pro varies,
depending on the applications you use and the external devices connected to your
MacBook Pro.
Turning off features such as AirPort Extreme or Bluetooth ® wireless technology and
reducing screen brightness can help conserve battery charge, for example, when you’re
traveling by air. Many of your system preferences are automatically set to optimize
battery life.
Your MacBook Pro comes with two graphics processors, one for better battery life and
the other for higher performance. To switch between processors, open System
Preferences, click Energy Saver, select “Better battery life” or “Higher performance,” and
then follow the onscreen instructions.
You can determine the charge remaining in the battery by looking at the eight battery
level indicator lights on the left side of your MacBook Pro. Press the button next to the
lights, and the lights glow briefly to show how much charge remains in the battery.
Important: If only one indicator light is on, very little charge is left. If no lights
illuminate, the battery is completely drained and the MacBook Pro won’t start up
unless the power adapter is connected. Plug in the power adapter to let the battery
recharge. For more information about battery indicator lights, see page 56.