2. According to Apple official website's introduction above, 100% discharge is not needed, and Apple lithium-ion battery works in charging cycle mode. If the used (discharged) power reaches 100% of the battery capacity, you have completed a charging cycle, but it is not necessarily completed in one charge, so you only need to charge it in time when there is no power, and don't wait until it is lower than 20%. Every time a charging cycle is completed, the maximum capacity of the battery will be slightly reduced. After several charging cycles, at least 80% of the original battery capacity can be maintained. If it is lowered again, the battery needs to be replaced in time.