User's Manual

4. Slide the second battery pack all the way into the slot. Make sure to
observe the correct orientation (the ribbon strip must face outward for
future battery pack removal).
5. Close the media bay cover to secure the second battery pack.
 
On the exterior side of the second battery pack is a gas gauge for displaying
the estimated battery charge. When the battery pack is not installed in the
computer and you want to know the battery charge, you can press the
switch with a pointed device to see the corresponding value of indicator
segment that light green. The value of the corresponding green segment
indicates the relative percentage of the battery charge. The battery pack is
fully discharged when you see no segment glowing green.