I bought Lenovo G50-80 and installed window 8.1 on it. the problem was that when I charged it the percentage of power never exceeded 60%. I googled about this issue and found out that I should install energy management for my laptop, however, it turned out that the only energy management available is for my laptop is for windows 10 only and there is no version for windows 8 !!!!!!! what should I do?
You can try installing the Power management driver for Win 8.1.
Hope this helps. Let us know how you get on.