Aspire Cygnet User Manual page 60

Safety & Protective Functions
58
Overcharging Protection
If the battery voltage reaches 4.25 volts or when the battery is fully charged,
the device will stop the charging process and the display will turn off.
Total Discharge Protection
The device will stop discharging when the battery voltage falls below 3.0
volts. Please recharge the device.
Battery Protection
If the battery is inserted the wrong way, the device cannot be switched on.
Insert the battery in the right orientation.