The loss of the battery under normal use, the health of the battery is less than 80%. Generally, after charging the iPhone for more than 500 times, that is, after using the iPhone for about 14- 18 months, the battery life will be reduced and the capacity will reach about 80%. It is recommended to change the battery. Because Apple takes 80% as the threshold, if it is lower than 80%, the system will forcibly turn on the performance management function, and the mobile phone will be stuck. It is recommended to replace the battery.