Sony VAIO PCG-F400 User Manual page 53

Using Your Notebook Computer
Using a Second Battery Pack
.
To charge the second battery pack
Keep the battery pack in the computer while it is connected to AC power. The battery
indicator flashes while the battery is charging. See also "To charge the battery pack"
on page 21 for more information.
.
Battery pack
(supplied)
Battery pack
Weight Saver
Battery indicators
Secondary battery pack
(not supplied)
n N 53