How to test the battery health?

How to check the battery health of Apple mobile phone: Go to Settings-Battery-Battery Health (Beta) and check the battery health at the maximum capacity. Note: If the battery is less than 80% healthy, it is recommended that you contact your local AppleStore or a third party to authorize the replacement of the battery after sale. Extended information 1. Mobile phone battery consists of three parts: battery core, protection circuit and shell. At present, all mobile phone batteries are lithium-ion batteries (often referred to as lithium batteries in irregular situations), and the cathode material is lithium cobalt oxide. The standard discharge voltage is 3.7V, the charging cut-off voltage is 4.2V, the discharge cut-off voltage is 2.75V, and the unit of electricity is Wh (watt-hour). Because the standard discharge voltage of mobile phone battery is 3.7V, it can also be replaced by mAh (milliampere hour). The conversion relationship between these two types of units on the mobile phone battery is: watt-hours = ampere-hours ×3.7. 2. Overcharge, overdischarge and short circuit will seriously damage the performance of the battery and may lead to use risks. For this reason, there is generally a slender protective circuit board in the battery of mobile phones to prevent these risks.