Panasonic CF-17 Reference Manual page 17

Battery Power
When the remaining battery charge becomes low
Save your data and power off your computer
Following that:
Plug in the AC adapter, and fully charge your battery.
Use a spare battery if you have one.
If you have neither the AC adapter nor an extra battery, power the computer off.
Red indicator lights
Beep sounds*
(at approx. 9% capacity)
*
When disabling the speakers with the Setup Utility (or pressing
warning beep is also disabled.
Suspend Mode
(at approx. 2% capacity)
17
Fn + F4 ), the