Battery \ software bug?

When I power my laptop to 100%, it tells me I have 2.x hrs left of battery. Two hours later, it tells me I have 6.x hours left. When I hibernate and wake the laptop it tells me again I have 2.x hours and an hour later I have 4.x hours left.

This is confusing, and I do not know what I have really left.

Same problem, on windows 10