I own since 2015 an Acer C720 which works like a dream and fulfills all my needs. After some years the battery seemed to go to EOL. It went down from 100% to 50% in 2 hours relatively linear, and then from 50% to zero within a few minutes. So, what? I just bought a new battery (the dealer claimed "Acer original"). This showed on first boot 100% and lasts for around 4,5 hours, After this, it charged only to 78% and the amber light turns blue, but the battery level shows 78% only. During the next few days this maximum went up day by day by 1%. And while working it lasted yesterday from 88% to 12% four hours and the rest was consumed within 2 minutes. What does this mean, that the maximum does not reach 100% ?