so 24 hours if you empty task manager, put it on brightness level 0.5 and don't touch it?
i like how vague they are about what it was doing and how much it will vary depending on what you are doing, 24 hours is clearly best case scenario if you never use it lifetime... otherwise they would quote an 'upto' number sorta thing. my macbookpro can 'sleep' for 3 days without actually dying from lack of battery