A LiFePO4 battery management system turns a group of “dumb” batteries into a smart battery pack.

The LiFePO4 battery management system is a necessary technology to ensure the safety and reliability of lithium iron phosphate batteries. Battery management also provides an interface for interaction with external systems, such as charging power, switching devices, loads and data display equipment.

The rapid development of electric vehicles in automobile manufacturing plants and related manufacturers has benefited from the higher performance and more complete functions provided by the battery management system. The management of management can be divided into two sciences, battery monitoring and battery control; the monitoring part includes voltage and temperature measurement and battery balance. These are the basic attributes of a battery management system.

Although the lithium iron phosphate battery is still safe under abuse conditions such as short circuit, overcharge, squeeze, and needle sticks, it will greatly affect the cycle life of the battery. The production process of lithium iron phosphate batteries is more complicated. The consistency difference of single cells will be greater than that of sealed valve-regulated lead-acid batteries, which causes the voltage of individual cells of the battery pack to rise rapidly in the later stage of charging. In addition, the communication room is unmanned for a long time. The on-duty status is not easy to find in time. This will cause the life of the lithium iron phosphate battery pack to be shortened or damaged. In order to avoid the occurrence of the above phenomenon, a power management system is required to ensure the safety and reliability of the battery.

The Battery Management System (BMS) is the core component of battery protection and management, not only to ensure the safe and reliable use of the battery, but also to give full play to the performance of the battery and prolong the service life, as the backup power for communication, management The system acts as a bridge between the high-voltage DC power supply and the battery. The requirements for the battery management system must meet the requirements of the communication power supply system, so the safety management mode of the battery management system is very important to the safety of the battery. The battery management system mainly includes a data acquisition unit, a calculation and control unit, an equalization unit, a control execution unit and a communication unit.

The basic role of the LiFePO4 battery management system

1. Monitor the working conditions of the single cells, such as detecting the voltage, charging and discharging current of each single cell, and the ambient temperature of the battery pack, etc.
2. Protect the battery to avoid shortened battery life and battery damage under extreme conditions.

The main functions of the battery management system

1.  Overvoltage protection
   When the charging voltage of the single battery exceeds the allowable value, immediately stop charging and disconnect the charging device from the battery pack:
2. Over-discharge alarm
   When the discharge voltage of the single battery is lower than the warning value, an alarm will be issued;
3. Over-discharge protection
   When the discharge voltage of the single battery is lower than the protection value, immediately stop the discharge, disconnect the electrical equipment from the battery pack, and give an alarm;
4. Over-current alarm
   When the battery pack input or the output current exceeds the warning value, an alarm will be issued;
5. Short circuit protection
   When a short circuit occurs in the battery pack, immediately stop discharging, disconnect the electrical equipment from the battery pack, and give an alarm;
6. Over-temperature alarm
   When the battery temperature or the ambient temperature exceeds the warning value, an alarm will be issued:
7. Over-temperature protection
   When detecting that the ambient temperature or the internal temperature of the battery pack exceeds the protection value, immediately disconnect the charging or electrical equipment from the battery pack, accompanied by an alarm. When the ambient temperature or the internal temperature of the battery pack returns to the allowable value, the battery management function can be restored manually or automatically, but it does not affect the battery discharge function;
8. Estimating the SOC of the LiFePo4 battery pack
   SOC (State of Charge, the state of charge of the battery), that is, the remaining battery power. Keep the SOC within a reasonable range. Prevent damage to the battery due to overcharge or over-discharge, and predict the remaining capacity of the battery at any time;
9. Balance the cells in the battery pack
   Due to the complex manufacturing process of lithium iron phosphate batteries and the relative activity of lithium ions, there is an inconsistency in the voltage of the single cells in the battery pack. Perform equalizing charging of the single cells in the battery pack to make the single cells in the battery pack reach a balanced and consistent state, which can effectively extend the service life of the battery pack and greatly improve the efficiency of the battery pack (this function can be based on User requirements increase or decrease).
10. Parallel communication
    Provides an interface for communication with the base station monitoring system, transmits and displays battery pack status, alarms, SOC and other information to realize remote monitoring and management intervention.

Nowadays, the lithium battery market is expanding. The improvement of LiFePo4 battery management system is the key to the safety, high efficiency and reasonable cost of lithium iron phosphate batteries.