Sony VGN-B1XP Hardware Manual page 21

Removing the battery pack (VGN-S series)
To remove the battery pack, proceed as follows:
1
Turn off the computer and close the cover.
2 Slide the lock lever (1) to the Unlock position.
3
Slide and hold the release lever (2) as indicated and slide the battery away from the computer.
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Using your VAIO computer