Experiments on lithium batteries have proven that shallow charging and discharging maximizes the cycle life of the battery, if the loss of charge from 0% to 100% is recorded as 1 cycle, then * Charge to 90%, only 0.52 cycle * Charge to 80%, only 0.27 cycle Battery Guard can set high and low thresholds and then alerting the user when the power reaches the threshold, so that the battery maintains a shallow cycle working state. App features are as follows: * Light and compact App, less than 200k. * Support text, vibration and voice alarm when the power reaches the threshold. * Voice alarm uses TTS engine and supports custom voice. * Backend records daily battery cycle loss and generates daily, weekly and monthly statistical charts. * Record battery temperature and generate daily, weekly and monthly statistical charts. * Record daily bright screen time and generate daily, weekly, and monthly statistical charts. * Support charging and discharging details, including charts of power, temperature, current, etc. In addition to the basic battery-related statistics, the following functions are supported. * Support daily, weekly, and monthly screen time statistics. * Support daily, weekly, and monthly temperature range statistics. * Customizable notification bar icons and functions Battery monitoring requires background operation, please refer to the help to reserve the background correctly.