Even in a scenario like that seems like there's something off there. Either with it being on 100% for 10 hours and/or with a drop of 20% in mere minutes. Sure, drops are faster once you are out of the initial 5-10% of usage, but things shouldn't be dropping 20% in just mere minutes.That does not mean a thing really since it may have been on the previous reading for a long time. ie on 100% for 10 hours and then drops 20% does not mean there is a problem.