Power Management software on my VAIO can not limit the battery level at %80 any more. I don't know what is broken, and I have no time/will to find and repair it. As a temporary solution, I wrote a PowerShell script to alert me with a sound when;
- the battery level fell under the specified lower limit and the laptop is discharging
- or the battery level exceeds the specified upper limit and the laptop is still connected to AC.
In other words, this script helps me to keep battery level in the range I specified (or 40-80 by default). How it helps? You need to plug-in or unplug the cable when you hear the sound :)