Panasonic Toughbook CF-27 Series Reference Manual page 15

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.
If the suspend or hibernation function is set
Red indicator lights
Beep sounds*
(at approx. 9% capacity)
If the suspend or hibernation function is not set
Red indicator lights
(at approx. 9% capacity)
*
When disabling the speakers with the Setup Utility (or pressing
warning beep is also disabled.
Suspend Mode or Hibernation Mode
(at approx. 4% capacity)
Beep sounds*
(at approx. 4% capacity)
15
Computer
goes off
(at approx. 0% capacity)
Fn + F4 ), the