Following a BIOS update from 215 to 219 (latest version) for my Asus UX31A, battery % now reports as being on 84% when it should read 100% (as it does in Windows 8). This value will remain permanently on 84% and will never reach 100% when plugged into the mains. The little light on the power cable lights up as green colour suggesting battery is fully charged, thus confirming there is some kind of miscommunication between my hardware and xubuntu/xfce/kernel. This could be a Asus BIOS fault rather than a bug. Either way, I'd appreciate it someone would please investigate this and hopefully provide a fix. Prior to this BIOS update, my battery reached 100%. I'm using XUBUNTU 13.04 (upgraded from 12.10) Thanks Christopher
This problem appears to have been resolved with kernel v3.8.0-31 on xubuntu 13.04 (amd64) as it now correctly shows battery at 100% when fully charged. This bug report can therefore be closed. Regards Christopher