There are two methods of power management for your laptop; ACPI and APM. APM or Advanced Power Management is the older of the two and works with the BIOS of the computer.
The disadvantage of APM is that the BIOS functions and manages the power without any real understanding of the operating system. The advantage is that it is well supported by Linux distros. The APM daemon consists of three programs:
apmd – controls power management tasks
apm – command line access to print current battery status or suspend power
xapm – battery meter for X Window