High varying discharge rate

I got an Asus N76VB notebook. On Windows I can easily stay on battery for 3-4 hours in powersave mode, but on Linux (first Ubuntu 14.04, currently Fedora 20) the battery's discharge rate varies from 10 watt to 40 watt (~25 watt mean) on powersave mode with backlight on the lowest possible value, resulting in 1-2 hours of battery life. I've tried: - Installing Bumblebee (with nVidia drivers) - Installing TLP (with most powersaving configuration) - Enable all tunables in powertop (already done by TLP) Powertop shows the following: [](https://i.sstatic.net/JvERD.png) I've no idea of any other causes of the high discharge rate. What's an average discharge rate? Currently I've only opened a terminal and Google Chrome window with this page and a YouTube video, on a almost clean Fedora installation, but it also happens with Firefox or without YouTube video. Any help would be appreciated!