Hello,
First, happy new year 2016 to everybody !
Globally, the desktop computers with Linux
don't save the battery so long than those with Windows,
(and maybe than those with Mac Apple) :
about 3 hours with Linux and more than 6 hours on Windows.
(no test with Apple).
This is a (rare) serious inconvenience for Linux.
The kernel doesn't manage correctly the energy usage
of the battery, compared to Windows.
Hope it will better in a few months, this is important
for the travellers.
André