Acer Aspire One Nav50 battery not fully charging... Stuck at 59%

Recently noticed a problem with my Acer Aspire One netbook.

When charging, the power management icon only charges until 59%. The netbook is still showing that it is plugged in and charging but only until 59%.

I tried to check the forums and the net for help before I go to a service center.

The troubleshooting steps that I already did are the following:

1. Update the BIOS version to latest one - did not work

2. Removed the battery and disconnected ac adapter then completely drained netbook of it's the residual power. According to the step, I needed to hold down on the power button for 2 mins to drain and connect back the battery and the ac adapter. - this did not work as well.

I'm not sure if this is a battery problem. In my opinion and experience with laptops and batteries, charging will still reach 100% it's only the battery life that deteriorates.