Li-ion batteries are widely used in various devices due to many advantages such as high working voltage, small size, light weight, high energy density, no memory effect, no pollution, low self-discharge, and long cycle life.

　　However, li-ion batteries also have certain shortcomings. In summary, there are the following aspects:

　　The safety of lithium iron phosphate (LiFePO4) batteries is relatively high, but it will be relatively poor if using LiCoO₂ as the positive electrode material of li-ion batteries.

　　Li-ion batteries are sensitive to ambient temperature: if they are used at too high a temperature, they may cause the electrolyte to decompose, burn or even explode; If the temperature is too low, the performance of the li-ion battery will deteriorate and affect the normal use of the device.

　　There will be differences in the internal resistance and capacity of each li-ion battery cell. When multiple li-ion battery cells are used in series, the charging and discharging rate of each battery cell will be inconsistent, which leads to a low utilization rate of the whole battery pack capacity.

　　Therefore, the li-ion battery must be equipped with a BMS, so as to realize effectively monitor, protect, balance and fault alarm.

　　BMS - Battery Management System, it usually has the functions of measuring battery voltage, current, temperature, etc., to prevent or avoid abnormal conditions such as over-discharge, over-charge, and over-temperature of lithium ion batteries.

　　Some advanced li-ion battery BMS have functions of accurate charge state estimation, RS485/CAN communication, Bluetooth or remote online monitoring.

　　In order to solve the defects of lithium ion batteries, the escort of the BMS is necessary. The reasonable configuration of li-ion battery BMS is of great significance to the use of li-ion batteries.