Re: "0.8 per cent of the 2800 mAh battery per hour"
"clearly too dense"
Not at all... I did the calculation in my head, so it's not exact. It's about 20% of battery life over a 24-hour period - or as Seajay has commented, it would be 20% over a 25-hour day.
24 hours times 0.8% per hour = 19.2%. So 20% wasn't a bad estimate... :-)