Android Phone turns off when below 40%

[AC Question]

Last year I bought a Samsung Galaxy Note 2 and everything works fine until 7 months later.When it is below 40%, it turns off and I can't open it back off unless I charged it again. I tried a factory reset but still happened.Please help as it blocks my way of work.

 

[belodion]

It could be that it needs a new battery. Does the battery graph in Settings, Battery, Battery Usage show a sudden vertical drop to zero?

 

[B. Diddy]

Welcome to Android Central! I agree with belodion -- definitely try a new or different battery. Batteries can be defective or fail. The Note 2 is an old phone, so even though you got it last year, it's certainly possible the battery wasn't brand new.