Sony PCG-F640 - Manual (Page 55)

Using a Second Battery Pack
55
1 There is a Release lever on the bottom of the weight saver. To remove the
battery pack, slide this lever in the direction of arrow 1, then slide the
RELEASE lever on the bottom of the computer in the direction of arrow 2.
2 Remove the weight saver, and then pull out the battery pack.
3 Reinsert the weight saver. See “Using the Weight Saver” on page 56.
Multipurpose bay release levers
Arrow 1: Weight saver Release lever
Arrow 2: RELEASE lever