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hello i get some problem for my 6s phone when i trying big size app like (game) PUBG , Inside and antutu test , its always restart and close that app and when battrey turn to 10% my phone turn slow . please answer . what must i do guys. Update (06/26/2018)

check this out guys Update (06/27/2018) can please someone explain , my battery condition is good when i look in 3utools . but why this problem dosent solved

u just need a new battery. apple made it so the phone slows down/shuts down if the battery cant supply proper power to the cpu