Mac seems to use alot of CPU power and gets hot when on lock screen/sleeping, and on battery power. I i "forget" to pull the power over night and come back to the mac in the morning, its very hot, which means it just has wasted alot of energy for no good. What's a good way of debugging this and how to fix it? I really don't want the mac to waste power when i'm not using it.
Have you tried an SMC reset? System Management Controller "can resolve certain issues related to power, battery and other features." according to Apple's website.
There are different methods for resetting SMC, depending on your model. Here is a link to Apple's site with instructions for resetting SMC.