I have had my Nexus 7 for about 2 1/2 years now and just started having this problem. I charge my tablet to about 80-90% during the day then go to bed. On average, i watch about 2-3 hours of Netflix. Last night, when i fell asleep, (about and hour into my show) i checked the battery percentage. It was at 60%. I went to bed, and woke up a few hours later. I checked my percent and it was at 23%! I put my tablet in airplane mode, because I find that helps charge my tablet better. I woke up this morning, 5 hours later, to find my tablet saying it was at 23% and charging. It charges fine during the day, but not in the evening/night. I will try using my laptop for Netflix tonight and see if I still have that problem. I would like to find a way to fix this so i can also use my tablet during the day, not just at night.