why does my Samsung Galaxy turn off/die randomly at 15 % occasionally?

[BellaBear1996]

got a new battery two months ago and was fine, and now its turning itself off/dying (?) at 15 percent, sometimes it will last all the way to zero percent before it does this, but thats rare. Not sure whats happening. Very frustrating. Has to be charging to turn back on. Anybody else have this happen?

 

[jasonandrews25788]

damaged battery

 

[Rukbat]

There's a setting for when to warn you of a low charge and another one for when to turn the phone off due to a low charge. If you have the turnoff set to 15% and the warning set to 10%, you'll never get the warning, the phone will turn off at 15%

Another possibility is a dendrite forming in the battery when it gets down to 15%. That shouldn't matter, because you should NEVER allow a lithium battery to drop below 40% (unless you like getting a new battery every few months). See The Care and Feeding of Lithium Polymer Batteries.