Generally speaking, after the health of Apple xs battery is lower than 80%, it is necessary to consider replacing the battery, because after it is lower than 80%, the battery life will be short and it will be charged several times a day. However, even if it is lower than 80% in actual use, it doesn't have to be replaced, but it depends on whether you can stand it. If it is less than 80% after the warranty period, if it can be charged and discharged normally, it can be charged several times a day, and it can continue to be used without replacement.