Turn off the computer, or enter hibernation mode. Then disconnect the ac adapter and all cables from the computer. Notes:
If you are using a PC Card or an SD Card, the computer may not be able to enter hibernation mode. If this happens, turn off the computer.
If you are replacing the hard drive, do not enter hibernation mode. You must turn off the computer.
Close the computer display, and turn the computer over.
Slide the battery latch to the unlock position
Slide and hold the battery release latch to the unlock position (1); then remove the battery (2).
Align the front of the spare battery with the front side of the battery space in the computer; then gently push the battery into the space . Note: Before installing the spare battery, attach the spacer if it is not attached (1), and secure it with two coin screws (2).
Slide the battery latch to the locked position.
Turn the computer over again. Connect the ac adapter and the cables to the computer.
Additional information
Turning the computer off and removing the battery pack are the first steps for all option parts removal and installation instructions.