Samsung NV20 Manual page 63

To extend the battery's life span
When the battery is in continuous use without being completely charged or discharged,
there may be a difference between the displayed battery charge and the actual battery
charge, owing to the inherent characteristics of the battery.
Battery calibration process, which is completely discharging the battery and fully
recharging it, can correct this problem.
1. Turn off the computer and disconnect the AC adapter.
2. Turn on the computer and press <F2> to enter System Setup.
3. Select Smart Battery Calibration in the Boot menu, and press <Enter> to start.
The calibration process usually takes 3 to 4 hours depending on the remaining
battery charge.
4. When the calibration process is complete and the battery is completely discharged,
connect the AC adapter to fully recharge the battery.
Using the Battery 55