Battery pack removal and installation - 3000 V100, V200
Turn off the computer, or enter hibernation mode. Then disconnect the AC adapter and all cables from the computer. Note: If you are using an ExpressCard, the computer may not be able to enter hibernation mode. In such a case, turn off the computer.
Close the computer display, and turn the computer over.
Unlock the battery latch  to the unlocked position.
Unlock the battery latch  by sliding it to the unlocked position. Holding the latch in the unlocked position, remove the battery .
Install a fully charged battery .
Slide the battery latch to the locked position .
Turn the computer over again. Connect the AC adapter and the cables to the computer.