Prentke Romich Company
http://www.prentrom.com/support/article/332
The average life span of the Liberator battery pack is around 2 years. With monthly calibrations,
the battery may last as long as 3 years.
To calibrate the batteries, the pack must be fully charged and the charger plugged in.
1. Turn the unit ON.
2. Lift up the keyguard, (opening the Toolbox).
3. Select System Function Menu, located at [L2].
4. Hit number #7 next screen until you find the Maintenance Menu and select it.
5. Select #3, Calibrate Battery Pack.
6. Follow the instructions on the display. If you want to continue hit Y for Yes located at [H5].
The calibration test will drain the batteries to 0 volts and then charge them to 8 volts. Initially all the lights on the unit will light up, with a message "Discharging to find end of battery". This is how the Liberator drains the battery. The battery LED will flash amber during the calibration. Once the Led is solid green, the unit has finished the calibration and is ready to use.