I often put my laptop to sleep at the end of the day with 20%+ battery remaining. When I open it the next morning, it complains that it's at dangerously low battery; it seems to have used up 10% or more just sleeping for eight hours.
The laptop is less than a year old. What's going on here? Is it waking in the middle of the night and ordering itself goodies off Aamzon? Does it have COPD?
My old Windows machine would wake/sleep repeatedly through the night, attempting and failing to hibernate...but I've never heard of a Mac doing that.