the problem happens because your battery degrades over time.. but android still thinks it is the same battery as it was before degradation. this calibration issue arises.
your phone will automatically recalibrate its battery when you charge it from 0 to 100 percent few times. night is the best option. when your battery drains below 5 percent put your phone to charge till morning. do it 4 or 5 times each night. it will...