I used the laptop for about one year with 12.10, battery detection worked mostly correctly.
Mostly means that I needed to reset the battery a couple of times during that period.
I recently installed 13.10 with kernel 3.11.0-15-generic.
After the upgrade, battery detection did not work neither worked after downgrading the kernel
to 3.11.0-12 nor after upgrading to 3.12.6 (upubuntu).
I went back to kernel 3.11.0-15-generic and reset the battery twice. Battery detection now works!
My inference is that the bug does not have anything to do with the kernel version.
I have a NP900X3C-A02UK with BIOS P04AAC.
I used the laptop for about one year with 12.10, battery detection worked mostly correctly.
Mostly means that I needed to reset the battery a couple of times during that period.
I recently installed 13.10 with kernel 3.11.0-15-generic.
After the upgrade, battery detection did not work neither worked after downgrading the kernel
to 3.11.0-12 nor after upgrading to 3.12.6 (upubuntu).
I went back to kernel 3.11.0-15-generic and reset the battery twice. Battery detection now works!
My inference is that the bug does not have anything to do with the kernel version.