Hi andi,
As Mark says, the operating life of your battery depends upon what you use
your laptop for. However, the display format of charge remaining is dependant
on the laptop manufacturer and the driver that it uses to report battery
status. Some give a percentage, some give a time remaining and some give
both. In all cases, the status is an estimated value of battery life
remaining. Unless the laptop manufacturer supplies another driver enabling
you to monitor the battery life in another format, then I'm afraid that you
are stuck with it being reported as a percentage.
Dwarf