If the battery cell is compared to the human heart, and the modules and battery packs are compared to a strong physique, then the entire power battery system needs a smart brain that governs the body, which is BMS.

　　The Battery Management System (BMS) is an important link between the battery and the electric vehicle. Precise control and management are its main functions.

　　Even if two single cells produced in the same batch are affected by factors such as production process errors and use environment differences, their performance may not be completely consistent. In the course of use, this inconsistency will gradually expand, and there may be dangers of overcharging, over-discharging and local overheating, which may affect the service life and safety of the battery pack in serious cases.

　　At this time, BMS is needed to show its talents. So, what does BMS mainly do?

　　1. Accurately estimate the state of charge of the power battery pack

　　Accurately estimate the state of charge (State of Charge, or SOC) of the power battery pack, that is, the remaining battery capacity, to ensure that the SOC is maintained within a reasonable range, to prevent damage to the battery due to overcharge or over-discharge, and to predict the charge of the energy storage battery at any time Electric state.

　　Regarding the estimation of the battery state, a series of complex calculations are required. The estimation method based on battery parameters can effectively eliminate the influence of accumulated errors and make the estimation more accurate. Generally speaking, the accuracy of NCM estimation is 5%, and the accuracy of LFP is around 7%.

　　2. Dynamically monitor the working status of the power battery pack

　　In the process of battery charging and discharging, the voltage, temperature, current, and total system voltage of each battery are collected in real time to prevent the battery from being overcharged or over-discharged.

　　At the same time, the battery status can be given in time, the problematic battery can be selected, and the reliability and efficiency of the entire battery pack can be maintained.

　　In addition, it is necessary to establish a history file of each battery to provide information for further optimization and development of new types of electricity, chargers, motors, etc., and to provide a basis for offline analysis of system failures.

　　3. Balance between single cells

　　Equalize the single battery, so that each electric cell in the battery pack reaches a balanced state. Equalization technology is the key technology of a battery energy management system that is currently being researched and developed in the world.

　　4. SOH report

　　SOH (State of Health), SOP (State of Power), users can display and see these data through various software interfaces to confirm the working and functional status of the battery. In this way, on the basis of protecting the battery, the friendly function can be maximized, and the user's intuitive experience can be greatly improved.

　　The industry believes that installing an excellent BMS can effectively improve the utilization of the battery, prevent the battery from overcharging and over-discharging, and prolong the service life of the battery, monitor the battery pack and the operating status of each battery in time, and effectively prevent the battery pack from spontaneous combustion, such as Early warning is given in case of emergencies to gain time for safety.

　　Lithium-ion battery (LIB) has become the main energy storage solution in modern social life. Among them, lithium iron phosphate batteries are a perfect replacement for lead-acid batteries, and they are the first choice for grid-connected peak shaving, off-grid energy storage, photovoltaic energy storage, UPS, data center and other industries.