Recently, i noticed that on my laptop, it didn't last as long as it used to be. I think this happened after i upgraded to Linux Kernel 3.6.x. Previously, i was using Linux Kernel 3.5.4 and it was fine and it could last for 8-9 hours, but now, it only last for at maximum of 5 hours.
Perhaps there was a regression on the Linux Kernel or perhaps i didn't reconfigure my laptop-mode package after i upgraded to the latest version? Well, i need to sort this problem out when i have time. Now is not the time unfortunately :(