Battery Management System – tracking EV battery pack health

An electric vehicle’s functions are significantly reliant on its batteries, making them a critical component that requires constant monitoring and control. An EV Battery Management System (BMS) is required to accomplish this.

Because of their environmental friendliness, energy efficiency, and lower operating costs, electric cars (EVs) are gaining popularity. However, EVs present distinct issues, one of which is battery management. Electric vehicles are powered by various types of batteries, and which battery is ideal relies on its energy storage efficiency, production costs, structural qualities, safety, and lifespan.

“It is true that EVs have been gaining popularity in recent years as charging infrastructure improves and battery technology becomes more efficient. According to IEA, the figure of electric cars on the road could reach 145 million by 2030. Furthermore, main automakers have been investing a lot in EV machinery and introducing the latest electric models to their lineups. Overall, the transition to EV is well in progress, and it seems likely to continue as more with the environmental and economic benefits of electric vehicles, shares Dr. Abhishek Choubey, Head- Industry Institute Partnership Cell (IIPC) & Associate Professor, Department of Mechanical Engineering, Sagar Institute of Science Technology & Research (SISTec), Bhopal.

In electric vehicles, lithium-ion batteries are the most commonly used technology. EVs are powered by high-voltage lithium-ion battery packs. When compared to other battery chemistries, lithium-ion batteries offer a higher energy density (100-265wh/kg). They can catch fire in unexpected circumstances. To ensure the safety of both the user and the vehicle, electric vehicles must be operated within pre-defined safety parameters.

“BMS is a critical component of every EV today as it is needed to manage battery performance, adjust power output on the go, and facilitate safe charging. At Lohum, we link BMS to our smartphone app and rapidly determine accurate battery residual value to unlock new 2nd life applications for used EV batteries, such as off-grid EV charging stations, ESS and UPS systems, and more,” explains Rajat Verma, CEO & Founder, Lohum Cleantech.

Lithium-ion batteries can have minor changes in capacity and resistance, which can cause pack imbalances over time. Overcharging and overheating might occur if the cells become too unbalanced. As a result, it has become an important aspect of EV consumption that must be constantly checked and controlled. As a result, an EV Battery Management System is required. (BMS).

A BMS, which manages the electronics of a rechargeable battery, whether a cell or a battery pack, is thus an important aspect in guaranteeing the safety of electric vehicles. It protects both the user and the battery by keeping the cell within its safe operating parameters. It functions as the battery’s brain, ensuring that it runs within safe limits and maximizes its lifespan. Its primary purpose is to protect the battery and prevent any acts that might surpass its safety level. BMS can monitor battery temperature, state of charge (SoC), state of health (SoH), and cell voltage balance, among other things.

Overheating is a major worry with EV batteries, which can lead to thermal runaway, a dangerous situation in which the battery rapidly heats up and releases gas, potentially resulting in a fire or explosion. Lithium-ion batteries are temperature-sensitive, and high temperatures can result in decreased performance and rapid breakdown. As a result, the BMS must ensure that the battery maintains a safe temperature range even when subjected to heavy loads or adverse climatic conditions. These systems can be passive or active, with the cooling medium being a non-corrosive liquid, air, or phase transition. The most basic method of controlling battery temperatures is to use air as a coolant.

Cycling (charging and discharging), high temperatures, and aging all contribute to the degradation of lithium-ion batteries over time. The BMS not only manages the battery’s performance and safety, but it also helps to extend its lifespan. The BMS monitors the battery’s SoC and SoH. SoC denotes how much charge the battery has, whereas SoH denotes how much capacity the battery has lost over time. BMS guarantees that the battery is not overcharged or discharged beyond safe limits, preventing battery damage and extending battery life.

BMS is also responsible for balancing cell voltage. The voltages of the cells in an EV battery pack might vary, resulting in an imbalance that can degrade the battery’s performance and lifespan. BMS maintains cell balance by spreading charge between them. The BMS also communicates with other systems in the EV, like as the motor controller and charging system, to ensure that they run within safe limits and are battery compatible.

So, what are the design factors for a BMS? Dr. Choubey explains in simple terms:

Security: The safety of the battery and the surrounding equipment must be prioritized. The BMS should detect irregularities in the battery characteristics and take appropriate action to prevent overcharging and overheating.
Accuracy: The BMS should offer precise information about the battery’s status, including voltage, current, and temperature. The accuracy of the readings is critical for the battery’s correct operation and performance optimization
Scalability: The BMS should be built to accommodate various battery chemistries, sizes, and configurations.
Reliability: The BMS should be built to be long-lasting and require little maintenance.
Communication: To manage the charging and discharging of the battery, the BMS should be able to communicate with other systems in the car.
Power consumption: The BMS should consume as little power as possible in order to maximize the battery’s energy efficiency. When the battery is not in use, the BMS should be configured to operate in low-power modes.
Cost: The BMS should be cost-effective, and its cost should not add significantly to the overall system cost.

As a result, the battery management system is a vital component of electric vehicles, assuring safe and efficient operation while maximizing battery lifespan. The BMS optimizes performance and reduces the danger of damage or degradation by carefully monitoring and controlling the battery’s state of charge, temperature, and other characteristics. As EV technology advances, the function of the BMS in providing reliable and sustainable transportation will become ever more vital.

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