I have a Lenovo Z50-70 Laptop with dual boot between Windows 8.1 and Ubuntu 14.04 LTS. The battery lasts for about 6 hours on Windows but lasts only 2.5 hrs or less on Ubuntu. Since the difference is substantial, it doesn't seem normal to me.
I think it is some driver issue but I don't know how to solve it. I've already read this post but it didn't help. Any suggestions?
lspci -k | grep -EA2 'VGA|3D':
00:02.0 VGA compatible controller: Intel Corporation Haswell-ULT Integrated Graphics Controller (rev 0b) Subsystem: Lenovo Device 380d Kernel driver in use: i915 -- 03:00.0 3D controller: NVIDIA Corporation GM108M [GeForce 840M] (rev a2) Subsystem: Lenovo Device 380d