Apple MacBook Pro (15-inch) - Manual (Page 79)

Chapter 3 Using Your MacBook Pro 79
Charging a Battery
When the power adapter that came with your computer is connected, the battery
recharges whether the computer is off, on, or in sleep. However, the battery recharges
more quickly if the computer is off or in sleep. When the MacBook Pro is on, you can
monitor the battery charge level using the Battery status menu in the menu bar.
The battery charge level displayed is based on the amount of power left in the battery
with the applications, peripheral devices, and system settings (display brightness,
Energy Saver settings, and so on) you are currently using. To conserve battery power,
close applications and disconnect peripheral devices not in use, and adjust your Energy
Saver settings (see the next section).
Understanding Battery Conservation Tips
The amount of work time your MacBook Pro battery can provide before you need to
recharge depends on the applications and peripheral devices you’re currently using
and the steps you take to conserve power while you work.
For the best conservation of battery power, do the following:
 Disconnect bus-powered USB or FireWire devices when they are not in use.