battery problem on Thinkpad G40

After a first installation in my IBM Thinkpad G40 of a SUSE Linux 9.0 Professional it show a warning message that inform me the battery is low, but the notebook is connected to 220Volts and the battery is full charged. Why this? I don't find in the control panel more information about how to setup the complete power control via Linux, but only a checkbox how to show and play some alarm when the charge is low and extremely low... -- Calogero Bonasia