According to the current official description of Apple, the battery must be replaced after the battery health is lower than 80%. If the battery efficiency of the IOS system shows less than 80%, the running speed of the mobile phone will become stuck, which is called frequency reduction, which will slow down the running speed of the mobile phone processor. Usually, the battery of iphone can last for two years.
If the battery capacity of the Apple mobile phone you use is only 80% or less within the one-year warranty period or the warranty scope of the AppleCare plan, you can go to AppleStore or an Apple authorized service provider to replace the Apple mobile phone battery for free.