Sony PCG-F680 Manual

When you use a battery as the source of power for your computer, you can take 
advantage of power management settings to conserve battery life. In addition to 
the normal operating mode, which allows you to turn off specific devices, your 
computer has three distinct power saving modes: System Idle, System Suspend, 
and System Hibernation. When using battery power, be aware that the computer 
automatically enters System Hibernation mode when the remaining battery 
charge drops below 5 percent, regardless of the power management setting you 
select.

Normal mode is the normal state of your computer when it is in use. The power 
indicator light displays green when your computer is in this mode. To save power, 
you can turn off a specific device such as the LCD or the hard disk.

Use the System Idle mode when your computer is not in use for a brief period. 
Selecting this option places your hard disk and video display in a low power 
state, and the CPU clock and processor stop. The power indicator light is umber 
in this mode.

To activate System Idle mode, press the key combination Fn+S, or use the 
PowerPanel utility to activate the System Idle mode. 

Press any key to return to normal Mode.

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If the battery level falls below 10 percent, you should either attach the AC adapter to 
recharge the battery or shut down your computer and insert a fully charged battery.