Perhaps the calibratin is *NOW* off. Perhaps your battery is *NOW* dying. Could be either of these also.
Best way to help ascertain what's really going on is to leave it charging for a long time (until either 100% is reached, or else the time on the charger is at *LEAST* more than double the normal time it takes to charge your battery fully or overnight, whichever is easier to do). - It might even never go above 80%, seen that reported where battery will charge up to a certain point and go no further, indicating a bad battery.