Table of Contents
What is the Battery Management System?
Battery Management System (BMS) is actually the brains behind the monitoring of battery charging and discharging.
These electronic systems manage a rechargeable cell or battery pack. It ensures that it operates within the safety limits, enhancing the performance of the battery. As a result, BMS increases battery longevity. Moreover, it also prevents possible damage or accidents resulting from the misuse of the battery pack.
A BMS comes as a whole unit that includes the battery pack, the battery management system, a data bus for external communication, and a smart charger. The BMS may communicate the status of the battery through status displays, alarms, and lights.
A video about the Battery Management System (BMS):
The function of the BMS
1. Monitoring the status of the battery pack
The BMS monitors several aspects of the battery concerning the specified operating conditions. These aspects include the following:
Current: The current that the battery takes in and which goes out to power the equipment
Voltage: The BMS may monitor the voltage of individual cells, total voltage, and the minimum and maximum voltage when the battery is discharging or charging.
State of Health: This measurement checks the overall condition of the battery pack at any given moment.
State of Charge: The BMS indicates the charge level for the battery at any given moment. The measurement encompasses the level of charging and the depth of discharge.
For the fluid and air-cooled batteries, the BMS monitors the flow of the coolant.
Temperature: This measure may include the average temperature of the battery pack and the coolant’s temperature at the intake and the output. If the BMS is monitoring a battery pack with different cells, it may track the temperature of the battery’s individual cells.
2. Computing different energy values
In addition to the above parameters, the BMS may also compute data based on each of the above areas as follows:
- The total time that the battery has been in operation since its first use.
- The total energy delivered and the total number of cycles.
- Amount of energy in kWh since the battery was last charged.
- The charge delivered by the smart charger or stored by the battery. The system calculates charge in Coulombs.
- The maximum charge and discharge current as per their respective limits.
3. Energy Recovery control
In some cases, such as electric vehicles, the BMS redirects the recovered energy back to the battery pack. You may recover energy from such actions as regenerative braking. The function enables the battery to run the car engine longer without plugging into the power socket.
4. Protecting the battery pack
The primary function of the BMS is to ensure that the battery operates in a safe environment. It prevents the battery from operating outside this environment by controlling such parameters as over-current, high temperature, over-voltage, and very low temperature. Moreover, it may check the ground fault, detect current leakage, and guard over high pressure.
Should any of the above parameters be exceeded, the BMS may shut off the battery or ring an alarm. It may also request devices using the batteries to reduce their consumption or enhance the environment, such as starting the fans, air conditioner, or heater.
There are two types of communications handled by the BMS:
The first is internal communication, the communication between different system components to control such aspects as the charge, temperature, and discharge of the system. The BMS has a software system that acts in line with the set minimum and maximum. The actions ensure that the battery is always operating within a safe operating environment.
The second type is external communication, the interface between the Battery Management System and the user, such as the vehicle owner or the equipment operator. The values calculated above and the operating parameters are displayed for the user to see. The user uses the same interface to change the battery operating parameters and the values the BMS displays.
Some of the technologies used in external communications include the CAN-bus common in automobiles and the DC-BUS used over a power line. Other systems use wireless communications such as Wi-Fi or sim cards to communicate the status of the battery.
The Bottom Line
A Battery Management System eliminates the need to keep checking the status of the battery while using it.
It ensures that the battery runs as required and warns you of imminent failures or damage. Moreover, it optimizes the functionality of the battery for the smooth running of your machine.