Understanding Battery Management Systems In Electric Vehicles


An electronic regulator that monitors and regulates the charging and discharging of rechargeable batteries is known as a Battery Management System (BMS). Multiple types of battery management systems are used in most applications that use rechargeable batteries. These systems are popular in data centres, where servers are kept online by UPS (uninterruptible power supplies). Electronic devices today are more mobile and environmentally friendly than ever before. This development is being fueled by battery advancements in a wide range of items, from portable power tools to plug-in hybrid electric vehicles to wireless speakers. The most primary functions of this system are that it protects the battery pack by monitoring and calculating the state of charge, health and safety of the pack. 

How Do Battery Management Systems (BMS) Work? 

A battery management system is a combination of multiple hardware and software functional blocks. The different functional blocks used are briefly explained in the following sections. 

  • Cut Off FETs

These are transistors that are used for the connection and isolation of the battery pack between the load and the charger. The behaviour of this block is predicted by measuring the battery-cell voltages, current measurements, and real-time detection circuitry. 

  • Fuel Gauge

This block tracks the charge that comes in and goes out of the battery pack. The charge can be understood as the product of the current passed along and the total time required for the current to pass. When it comes to designing a fuel gauge, there are many options to do so.

  • Cell Balancing 
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It is important to keep track of the cell voltage of each cell in a battery pack to assess its overall health. To ensure proper operation and battery life, all cells have an operating voltage window where charging and discharging can take place. Generally, lithium-ion batteries are used in electric vehicles. The voltage of these cells generally ranges from 2.5V to 4.2V. The lifespan of the cell is greatly reduced when the battery is operated outside of its voltage range.

  • Temperature Monitoring 

Lithium-ion batteries provide a lot of current while maintaining a constant voltage, which can lead to a thermal runaway condition that causes the battery to catch fire making the construction of the battery highly volatile. This temperature measurement is not just for safety but it can also suggest if the battery is suitable for charging or not. 

  • Other Blocks 

Battery authentication, real-time clock (RTC), memory, and daisy chain are examples of other usable BMS blocks. For black-box applications, the real-time clock and memory are used wherein the RTC is used as a timestamp, and memory is used to store the data.

Impact Of Battery Management System On Electric Vehicles 

Since all Electric Vehicles (EVs) use rechargeable batteries, proper battery maintenance is essential for the vehicle’s appropriate operation. We need to look at the characteristics of these batteries, which are normally li-ion, to see how they affect vehicle design and the electrical grid. Multiple cell modules are arranged in series and parallel in EV battery packs. A battery management system in the battery pack keeps track of components close to the battery cells. Each cell inside an EV battery pack must be closely and accurately monitored during charging and discharging, as unbalanced cell voltage conditions can affect battery performance. 

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Battery management systems in electric vehicles track the output of individual battery cells in real-time. That is, each cell must be controlled to ensure that it is functioning properly and that cell load sharing is balanced. A BMS monitors the power voltage and stops the charging phase when the appropriate voltage is reached. BMSs shut down and send out an alert if any abnormal patterns in the power flow are detected. The BMS must also handle other vehicle functions in addition to battery control, such as the vehicle’s desired operating mode as to whether it is accelerating, braking, idling, or stopped which can then trigger necessary power management functions.  

Market Outlook For Battery Management System In The Coming Years 

The global battery management device market was worth USD 3.61 billion in 2018, and it is expected to develop by 19.0% CAGR from 2019 to 2025. The increased acceptance of Electric Vehicles (EVs) and Hybrid Electric Vehicles (HEVs) around the world due to stringent policies will contribute to the growth rate. Lithium-ion technology is used in EVs because it has higher energy densities, less mass, and longer life than conventional batteries. The demand for BMSs is expected to skyrocket in the coming years, owing to the growing use of electric vehicles around the world and the growing demand for clean and renewable energy.

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A variety of functional blocks and design techniques can be used to create battery-management systems. The best design, functional blocks will be determined by careful consideration of battery specifications and battery-life targets in order to build a battery management system and charging scheme that maximizes battery life. The future is all about renewable energy which will promote the reliability and implementation of battery management systems.

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