Phone dies at 20%
I recently got a used iPhone 5s from my aunt. It is running iOS 9.2.1 and everything works fine exept for the fact that the phone will die with 27%, 25%, or 20%. When I plug it back in to charge the phone turns on again with the same battery percentage as it had when it died. Is this a software or calibration issue or do I need to replace the battery?
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