I have an Asus Zenbook UX31A, the Asus 13" unit from first generation ultrabooks. I run Ubuntu 12.10 up to date on it.
Before a week or two I used to enjoy more that 5 hours of battery life, especially when watching movies with VLC and hardware accelerated playback. I can't link my issue to some update I did but for several days now and after about 2 to 3 hours, my laptop shutdown abruptly without warning for critical nor low battery level.
I suspect this is battery related since the battery charge curve show that the battery charge plummets from 50-40% to 0% before the shutdowns. Upon reboot, I have to run a "killall Xorg" since the greeter won't load and drop me to something like a black console with lines about battery I can't remember on top of my head right now and an arrow cursor.
After a while, usually 1 to 3 minutes, the laptop shutdown again.
I can't pinpoint the component that cause this. I know it's a software problem since after such an event I can't run it for at least 1h30 in Windows without issues. I lost patience after that but it reported still 1h of autonomy when I powered it off.
Any hint on how to solve or at least identify the culprit ? Any log I can check maybe ?