My iPad says it has been off charge for almost 102 hours which is just over 4 days. In that time there is almost 9 hours use. However, if I look at the times for apps in the last 7 days (a greater period than the time off charge), the times do not add up to even close the stated 9 hours, more like 4 hours. I would expect the times for the apps in the 7 day view to add up to at least the period of usage over the last 4-5 days and possibly be more. Is there battery usage which is not measured here? General OS tasks? I would have hoped to see that listed under something- like home and lock screen perhaps. I would welcome a category for this in future iOS updates. What do you think?