Since a couple of days or so my laptop (asus n76vm) does a hard shut-down when the battery indicates 20% life left. It just cuts off the power, no shut-down screen or anything, making the hard drive do that nasty 'scratchy' sound.
What should I do now? It seems the battery is less powerfull than it was before (which makes sense) but the OS didn't keep track. How should I go about re-calibrating the battery?
2 Answers
Have you tried power-calibrate ?
sudo apt install power-calibrate then run
power-calibrate -r You can read the manual or run man power-calibrate for more information.
Update
As per the latest version of power-calibrate, use this command
power-calibrate -R -r 20 -d 5 -s 21 -n 0 -p Where
-d secs specify a delay before starting -h show help -n CPUs specify the number of CPUs to exercise -o file output results into YAML formatted file -p show progress -r secs specify run duration in seconds of each test cycle -R use Intel RAPL per CPU package data to measure Watts -s num number of samples (tests) per CPU for CPU calibration 
