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Insights on Automotive BMS Technology

by Aishwarya Saxena
BMS Cover Story

Electric vehicles run on rechargeable battery packs that are made of multiple cell modules arranged in a series and parallel.

Monitored by an embedded system, Battery Management System (BMS) manages the components closer to the battery cell, as each cell needs to be closely monitored so that there are no voltage fluctuations or imbalance in voltage conditions.

Focusing on the same, EV Mechanica has shared some insightful anecdotes from industry veterans namely, Sandeep Terwad, Global COE Head Embedded Solutions, Tata Technologies, Ankush Raina VP of Product Development, Log9 Materials, Manikanta Raju, Co-Founder, Lime.ai, Karthikeyan Adhikesavan, Co-founder & VP of Electronics, Raptee, Nag Mani, Director, RXN Electric Pvt Ltd., Amitabh Saran, CEO & Founder, Altigreen, Srikanth Reddy, Founder & CEO, Hala Mobility, Atul Gupta, Co-founder & Director, e-Sprinto, Raghuveer Chandalavada, CEO, Aurita Bikes and Rohan Shravan, Founder & CEO, Tresa Motors.

Role of BMS in EV Adoption

Battery management systems are critical components of hybrid and electric vehicles.

BMS in EVsSandeep Terwad, Global COE Head Embedded Solutions, Tata Technologies feels, Battery Management System (BMS) is crucial for the electric vehicle adoption. It functions well in executing its intended functions like State of Health (SOH) and State of Charge (SOC) monitoring, balancing cell voltages, range estimation, and keeping the battery and therefore the vehicle and its occupant safe by continuously monitoring parameters such as voltage, temperature, etc. and to control the same to ensure no overheating to minimize unsafe conditions. There are many more functions attributed to a BMS.

This is more of the same in that every BMS is expected to do all of the above. However, any OEM, Tier 1, or ESP that incorporates in addition to the above, the technological innovations, shall play a big role in differentiating from others and also help in accelerating the growth of the electric vehicle market.  Some of these are the usage of Artificial Intelligence (AI) and Machine Learning (ML) to enhance battery performance. ML in a BMS can help to adaptively optimize charging\ discharging based on real-time data and driving efficiency, thus extending the battery life. The BMS can help integrate predictive analytical functions to predict potential issues and suggest appropriate action.

Battery Management System can also help in exploring new revenue streams by having the BMS support bidirectional energy flow to participate in grid services. This integration of the BMS with the grid is known as vehicle-to-grid (V2G). One more important factor or concern from the end-user’s point of view is sustainability. A BMS can be designed with features to enhance the recyclability and reuse of battery components.

With the advances in battery chemistry, a BMS can also be designed to accommodate various battery chemistries. This evolution shall allow OEMs to diversify their product offerings, catering to different market segments and staying competitive in a rapidly evolving landscape.

In short, BMS will and shall play a crucial role both from the technical, safety, business, and environmental points of view to advance the growth of EV adoption.

Ankush Raina, VP of Product Development, Log9 Materials elucidates about how Battery Management System (BMS) plays a pivotal role in advancing the growth of electric vehicle adoption. In principle, the BMS is the brain of the battery pack. The Li – Ion battery pack, being the primary energy source for EVs, needs to be managed efficiently to gain longevity on a daily basis and also extend its life. The battery pack is made of individual cells where each cell is very unique in its inherent property. The BMS ensures that these cells function together in an efficient manner by enabling proper utilization at battery pack level. BMS also helps in optimizing performance and extending the lifespan of the batteries. It does so by monitoring and managing individual cell health, balancing energy distribution, preventing overcharging or discharging, and enhancing overall system reliability. By safeguarding the battery, BMS contributes to the safety and longevity of electric vehicles, addressing key concerns for consumers and supporting the broader acceptance of electric mobility.

According to Manikanta Raju, Co-Founder, Lime.ai, the adoption of electric vehicles is facing resistance due to multiple factors; one major contributor to this is battery safety. Battery management systems (BMS) contribute significantly to building and boasting trust among EV users. Given the volatile nature of lithium-ion batteries, the BMS plays a crucial role in managing their operations. Lithium-ion batteries require careful handling to ensure optimal performance and longevity. BMS ensures batteries are operated within safe operating limits. Beyond that, it incorporates diverse methods, including cell balancing, to decelerate battery degradation. BMS effectively neutralizes the asset-level risk of premature battery failure by implementing these comprehensive measures and ultimately enhancing battery lifespan. It also prevents the occurrence of thermal runaways, a primary contributor to battery fires.

Lime BMS, developed with eight years of expertise and testing involving 50,000 battery packs, stands as a robust example of this technology. It not only exemplifies durability but also fosters safety awareness among EV users. Lime’s real-time notifications, enabled by superior State of Charge (SOC) and State of Health (SOH) algorithms, enable preventative steps to avoid battery deterioration and provide vital insights into the remaining usable life of battery packs. What sets Lime’s BMS apart is its unique focus on both extending battery lifespan and safety, providing a comprehensive approach to asset management.

Karthikeyan Adhikesavan, Co-founder & VP of Electronics, Raptee expresses, the Battery Management System (BMS) in electric vehicles and Hybrid vehicles optimizes battery performance, ensures safety by preventing over-charging and over-discharging, also contributes to increased range and efficiency. Its crucial role in monitoring, balancing, and managing battery health which accelerates the growth and adoption of electric vehicles.

On the other hand, Nag Mani, Director, RXN Electric Pvt Ltd. mentions, the global shift towards sustainable transportation has accelerated the adoption of electric vehicles (EVs) and hybrids. Electric vehicles operate on lithium batteries that are known for their high energy density. However, these batteries come with a heightened sensitivity that, if mishandled, could lead to catastrophic consequences, including fires. This is where the Battery Management System (BMS) steps in as a crucial safeguard. It is particularly indispensable given that these lithium-ion batteries are not only highly sensitive but also costly. Therefore, it becomes imperative to extend their lifespan for economic reasons. Maintaining the health of the battery pack for an extended period is vital, and this task is efficiently executed by a robust BMS. By optimizing charging and discharging cycles, the BMS not only enhances safety but also ensures the longevity of the battery pack.

Amitabh Saran, CEO & Founder, Altigreen explains, Battery Management System (BMS) plays a critical role in the realm of electric vehicles, advancing the growth of electric vehicle adoption. It optimizes battery performance by ensuring efficient charging and discharging, maximizing overall energy output, and extending the driving range. Its active monitoring and management significantly contribute to prolonging the lifespan of the vehicle’s battery, reducing long-term ownership costs, and promoting sustainability. Additionally, the BMS enhances the safety and reliability of electric vehicles by preventing overcharging, over-discharging, and mitigating potential faults through continuous monitoring. Furthermore, the BMS’s role in enabling fast-charging capabilities addresses a common concern associated with electric vehicle adoption—reducing charging time and making electric vehicles more practical and convenient for users.

Srikanth Reddy, Founder & CEO, Hala Mobility talks about how BMS is key in the acceleration of EV adoption. It serves as the central nervous system for the vehicle’s battery, optimizing its performance and extending its lifespan. BMS plays a crucial role in enhancing the overall efficiency of electric and hybrid vehicles by ensuring precise monitoring, balancing, and protection of individual battery cells. This not only maximizes the driving range but also contributes significantly to the safety and reliability of the vehicle. At Hala, we ensure that data pulled from the BMS, coupled with AI and ML, helps you make smarter, better and data driven decisions for your fleet.

Atul Gupta, Co-founder & Director, e-Sprinto views Battery Management System (BMS) is integral to accelerating electric vehicle adoption. It optimizes battery performance, ensuring efficient energy usage and extending battery life. BMS monitors individual cell health, preventing overcharging or discharging, thus enhancing safety. It contributes to increased energy density, driving longer driving ranges. Additionally, BMS aids in thermal management, safeguarding batteries from extreme temperatures.

Raghuveer Chandalavada, CEO, Aurita Bikes comments on how Battery Management System (BMS) is akin to the brain of an electric vehicle battery (EV), orchestrating various functions crucial for widespread adoption. For instance, it optimizes charging and discharging cycles, enhancing the overall efficiency of the EV. Additionally, by ensuring the health and safety of the battery, the BMS addresses key concerns, fostering greater confidence among consumers to embrace electric mobility. Range per charge or mileage is a key factor for any consumer. BMS technology helps in maintaining optimal performance and life in order to achieve the desired TCO and thus holds a key role in driving growth.

Rohan Shravan and his BTS Team from Tresa Motors feels that the adoption of EVs will get a boost if EVs build a supreme reputation of being reliable and safe vehicles. BMS is one such component that plays a significant role in this dimension. BMS ensures the safety and reliability of the battery pack, which is the heart of an EV. It monitors and manages individual cell voltages, temperatures, and overall health to prevent overcharging, over-discharging, and overheating. This not only extends the lifespan of the battery but also enhances safety, assuring consumers of the durability and security of EV technology. Furthermore, BMS facilitates predictive maintenance, enabling early detection of potential issues within the battery system. This proactive approach minimizes unexpected failures and allows for timely repairs or replacements, reducing downtime and associated costs. The adoption of EVs will also be befitted from the high-performance attributes carried by them as compared to ICE vehicles. BMS optimizes the performance of the battery pack and enhances overall vehicle efficiency to improve vehicle performance. By balancing individual cell voltages and managing charging and discharging rates, it maximizes energy storage capacity and maintains consistent power delivery. This efficiency directly translates into increased driving range, addressing one of the primary concerns regarding EVs.

Factors to Consider while Designing a BMS

As mentioned above, a BMS must be engineered to execute functions like monitoring cell voltage, temperature, SOC, and SOH, communicating and exchanging data with the vehicle, preventing overheating, cell balancing, etc. efficiently. These functions are now considered basic and it is expected that all BMS do have it and are efficient in those functions. An OEM will lose out to competition if these functions do not work as expected or with the expected efficiency.

Nowadays with connectivity being the norm, Cybersecurity is coming into increasing focus. BMS designs should have robust security features to ensure the integrity of vehicle systems and gain customer trust. A BMS design should incorporate adaptive control strategies that adjust the parameters based on driving conditions, temperature, and other factors. This adaptability enhances the efficiency and performance of electric vehicles in various situations.

The current crop of BMS does have Functional Safety at the appropriate level already built-in, but Functional Safety (FUSA) is one of the key factors that must be taken into consideration right from the drawing board.

From the point of view of the safety of the driver, BMS design can actively control cell temperatures with dynamic adjustments based on real-time conditions. It can also have smart isolation systems, enhancing safety through advanced materials and technologies. BMS could evolve to offer more sophisticated emergency response systems, potentially integrating with autonomous driving systems for enhanced safety. The future designs must factor safety as a key factor right from the start as this shall help in reducing insurance costs for the end-user, explains Sandeep Terwad, Tata Technologies.

Log9However according to Ankush Raina, Log9 Materials, designing an effective BMS involves considering several key factors. First, the BMS must be tailored to the specific chemistry and characteristics of the battery pack it manages. It should incorporate precise voltage and temperature monitoring, state-of-charge estimation, and real-time data analysis. Safety measures are crucial, encompassing features such as overvoltage & undervoltage protection, and current limiting to ensure the safety of the driver and the overall vehicle. Additionally, the BMS should support communication protocols for seamless integration with other vehicle systems and external charging infrastructure. Advance BMS’ will also have the ability to provide balancing current to keep cells at optimum values with respect to each other.

Holding a similar viewpoint, Manikanta Raju from Lime.ai notes that designing a battery management system (BMS) encompasses various aspects, like efficiency, cost, compatibility with diverse cell chemistries, and understanding about the end-user application.

The primary function of BMS is monitoring and ensuring the safety of the battery. The BMS design should handle current and voltage demands effectively. Component selection should consider the heat generated by high current and voltage demands.

Selecting a balancing strategy for a BMS is essential for achieving optimal cell capacity. The choice depends on factors like battery chemistry, cell count, desired battery pack voltage, and specific application requirements.

During the component selection process for the BMS, the choice of processor is critical. It should have sufficient memory and good execution speed to deploy advanced state-of-charge (SOC) and state-of-health (SOH) algorithms.

Another crucial factor in BMS design is the ability to interact with other components of the vehicle. The BMS’s operation is controlled using various communication protocols like RS485, CAN, or Bluetooth, depending on user preferences. The selection of a suitable communication protocol for a BMS is contingent on the target application, ranging from inverters to 2-wheelers, 3-wheelers, and heavy-duty vehicles.

Therefore, the primary consideration during BMS design should be its intended use case, which will guide the development of advanced features for the specific application.

Battery Management System (BMS) designed for electric vehicles must evenly distribute energy among cells, monitor temperature to prevent overheating, and include safety features like emergency cut off to protect the driver from hazards. These measures ensure optimal performance and longevity of the battery while prioritizing the safety of the vehicle and the rider, justifies Karthikeyan Adhikesavan from Raptee.

Addressing the intricacies of BMS design, accuracy is a key consideration. The precision of any equipment can drift over time, influenced by factors such as temperature and environmental conditions. Ensuring the accuracy and reliability of a BMS over an extended period is essential for the seamless operation of electric vehicles. Additionally, the vibrational environment within a vehicle poses a unique challenge for electronic Printed Circuit Boards (PCBs). Prolonged exposure to vibrations can compromise the integrity of components on a PCB, potentially leading to a faulty BMS. Recognizing this vulnerability, BMS designs must incorporate measures to mitigate the impact of vibrations, ensuring the longevity and reliability of the system throughout the vehicle’s lifespan. Furthermore, preventing short circuits is a critical aspect of BMS safety. Short circuits pose a significant threat to both passengers and the vehicle. A well-designed BMS should incorporate stringent measures to prevent short circuits, clarifies Nag Mani from RXN Electric.

Altigreen Amitabh Saran from Altigreen describes that designing a Battery Management System (BMS) requires careful consideration of several key factors. First and foremost is the implementation of effective cell balancing algorithms, ensuring a uniform charge and discharge among individual cells within the battery pack. This approach prevents issues such as overcharging or over-discharging, ultimately optimizing overall battery performance and extending its lifespan. Temperature management is equally critical, requiring constant monitoring and control to prevent overheating and ensure the safety and longevity of the battery. Accurate State of Charge (SOC) estimation is another essential factor, providing users with reliable information about the remaining battery capacity and enhancing the overall user experience by preventing unexpected depletions.

Moreover, ensuring active thermal management functions and controlling battery temperature to avoid overheating are essentials. Automatic shutdown procedures provide a controlled response to critical faults, prioritizing safety to drivers or users. Moreover, adhering to safety standards and regulations are important factors that instil confidence in the safety of electric vehicles for both manufacturers and drivers.

On a different note, Srikanth Reddy from Hala Mobility views that designing a BMS, key factors must be carefully considered, including battery chemistry, temperature control, and charging protocols. Safety is paramount, and our BMS incorporates robust features such as thermal management, overcharge protection, and fault detection. By implementing these measures, we prioritize the safety of the rider and the longevity of the entire electric vehicle system.

Designing a BMS requires considering factors like accurate cell monitoring, thermal management, and communication protocols. Ensuring precise voltage and temperature monitoring across cells is crucial. BMS should incorporate overcharge and over-discharge protection, balancing cells to prevent uneven wear. Temperature sensors and cooling systems are essential for thermal management. Communication protocols must enable real-time data exchange with the vehicle’s control systems. To ensure driver safety, the BMS should have robust fail-safes, emergency shutdown capabilities, and clear fault indication systems. These measures collectively guarantee optimal performance and safety in electric vehicles, comments Atul Gupta from e-Sprinto.

Aurita BikesAccording to Raghuveer Chandalavada from Aurita Bikes, designing a robust BMS involves a nuanced understanding of multiple factors. Take, for instance, temperature control. In our design, we integrate advanced thermal management systems that actively regulate the temperature of the battery cells. This not only enhances performance but, more importantly, ensures the safety of the driver by preventing overheating-related issues. If we prioritise the issues surrounding battery performance, thermal management comes on top of everything else.

Rohit Sharavan from Tresa Motors clarifies that designing a Battery Management System (BMS) for electric vehicles requires careful consideration of several key factors to ensure optimal performance and driver safety.

  • Cell Monitoring and Balancing: The BMS must monitor individual cell voltages, temperatures, and state of charge to ensure each cell operates within safe limits. Implementing cell balancing techniques helps maintain uniformity in cell voltages, thus extending battery life.
  • State of Charge (SoC) Estimation: Accurately determining the SoC is crucial for providing drivers with accurate information about the remaining battery capacity. Utilizing sophisticated algorithms and models based on voltage, current, temperature, and coulomb counting techniques, the BMS estimates the SoC, ensuring drivers have reliable information about the available driving range and battery status.
  • Fault Diagnosis and Prognosis: Implementing diagnostic capabilities enables the BMS to identify faults or anomalies in the battery system. Prognostic algorithms can predict potential failures, allowing for preemptive actions to maintain safety and reliability.
  • Communication and Redundancy: Effective communication interfaces within the BMS enable real-time data exchange with other vehicle systems and external networks. Redundancy in critical functions ensures fail-safe operations, enhancing overall safety.

Regarding safety measures for the driver:

  • Temperature Regulation: Managing battery temperature is critical. Effective thermal management systems within the BMS prevent overheating and maintain an optimal operating temperature range for the battery cells.
  • Critical Measures: BMS should include safety features like overcharge and over-discharge protection to prevent battery damage or failure. Additionally, short-circuit protection, isolation monitoring, and insulation resistance checks are vital to ensure safety.
  • Emergency Shutdown: The BMS should include a mechanism for emergency shutdown in case of critical failures or hazardous conditions.
  • Clear Indicators and Alarms: Visual and audible alerts for drivers to indicate potential battery issues, ensuring prompt attention and action when required.
  • Regenerative Braking Control: Managing regenerative braking to prevent overcharging the battery and ensuring the driver’s safety during braking maneuvers.

Challenges Faced by BMS Designers in Development Stages

Tata Technologies has helped OEMs and Tier-1s in the design and validation of BMS. What we have observed is that BMS design needs a multi-disciplinary approach and cannot be categorized simply as a Hardware design or a Software design. BMS design teams must have people with very good skills in electrical engineering, people who have a deep understanding of battery chemistry and technology, thermal management, packaging and enclosure design, people with very good skills in hardware design, high voltage systems, design, application, and base software design. As mentioned previously AI and ML will also play a crucial part in the design, so having these skill sets as part of the design team shall also help.

The BMS design team should embed themselves with the powertrain and the vehicle engineering team right from the vehicle’s conceptual stage to understand the attributes of the vehicle so the BMS can be designed as per those vehicle attributes to make it efficient from the start. This is more of a process discipline.

Technically, the challenges involve handling cell variability, the fact that individual cells exhibit variations in voltage, capacity, and temperature characteristics, ensuring the safety of the battery pack, and preventing hazardous conditions, such as thermal runaway or overcharging, incorporating fault detection, diagnostics to predict faults. All these have to be designed with a certain product cost in mind without taking eyes off the efficiency, certification, and other product development costs.

A BMS is expected to last at least ten years. There will be advances in battery chemistry and batteries will evolve to be more efficient and more energy dense. BMS designers must peep into the future to make their designs as future-proof as possible, factoring in costs and current technology. The software can be upgraded through over-the-air (OTA) or other mechanisms but engineering the system with the future in mind is slightly challenging, justifies Sandeep.

Ankush notes that BMS is a mix of hardware and software solutions. BMS as a sub system interacts with the electrical wire harnesses and the mechanical components around it. The BMS designers face various challenges to build proper balance between various contradicting requirements from adjoining sub systems. One significant challenge is achieving a balance between maximizing battery performance and ensuring safety. Addressing thermal management, mitigating cell-to-cell variations, and implementing fail-safe mechanisms are other typical challenges. The rapid evolution of battery technologies poses a challenge in keeping BMS designs adaptable to new chemistries. Furthermore, the integration of advanced features, like predictive diagnostics and prognostics, demands continuous innovation. One also needs to keep an eye on the hardware cost and complexity of software code. Striking this balance between cost-effectiveness and performance is another challenge in the development of BMS for electric vehicles.

LimeAccording to Manikanta Raju, the primary function of BMS is monitoring and managing the health of the lithium-ion battery. Therefore, every aspect of the BMS should be designed diligently to meet all safety and performance standards.

Developing a battery management system (BMS) presents several challenges, one of which is choosing the appropriate architecture for the BMS board. The analog front end (AFE) is a critical component of the BMS, responsible for interfacing with analog signals from various current and voltage sensors. It provides crucial data about the amount of current, voltage, and other parameters generated by the battery cells. The BMS architecture is selected to meet the specific battery requirements, which again depend on the end-user applications.

Managing current is indeed a major challenge, and therefore the choice of contactors and MOSFETs is a critical decision. The choice between contactors and MOSFETs in the BMS depends on the specific use case of the user. The MOSFETs are economical but dissipate a lot of heat that needs to be managed. On the other side, contactors dissipate less heat but consume more power and are expensive in comparison to MOSFETs. Therefore, after understanding the user application, the designer proceeds to design the appropriate thermal management systems for the BMS.

A BMS should be developed in such a way that it can serve as an independent unit, protecting the battery and ensuring its proper operation. As a result, the design should take into account all of the protection from various noises from motors and controllers that can damage information necessary for the proper functioning of the BMS.

A significant challenge faced by BMS designers is the lack of comprehensive knowledge regarding various external systems. In addition to understanding external systems, designers should have a basic grasp of lithium-ion cells and battery operation.

Karthikeyan explains that BMS designers face challenges in keeping a close eye on battery cells, managing heat, and ensuring compatibility with various batteries. Balancing cells, overcharging, can promote longevity and efficiency in electric vehicle batteries. It’s a crucial aspect while designing Battery Management System.

Nag Mani clarifies Development of a Battery Management System (BMS) is a complex journey fraught with challenges, each requiring careful consideration and innovative solutions. One significant challenge arises from the absence of standardized protocols mandated by regulatory bodies. Unlike other automotive components, government regulations do not prescribe a standard set of protocols for BMS development. This lack of uniformity has led each manufacturer to tailor BMS designs to their specific needs. Consequently, the market is flooded with a variety of incompatible protocols, leaving consumers bewildered.

Furthermore, the influx of Chinese BMS, despite its longstanding presence in the market, has presented its own set of challenges. Despite reliability concerns, these systems are favored for their affordability and widespread availability. This has put pressure on other manufacturers to match these prices. Indian manufacturers have faced a tough time competing on cost. But the landscape is evolving, with advancements that may bridge the gap in pricing without compromising on quality.

There are several challenges involved in the development of Battery Management System (BMS). For instance, the rapid evolution of battery technologies requires constant adaptation and staying at the forefront of advancements. Ensuring seamless integration with new battery chemistries, energy storage systems, and emerging technologies is crucial. Another challenge in BMS development involves striking a delicate balance between optimal performance and cost-effectiveness. Designers consistently face pressure to create solutions meeting stringent cost constraints while maintaining high standards of reliability and safety. Moreover, meeting or exceeding regulatory requirements in different markets necessitates a keen awareness of evolving standards, adding a layer of diligence to the development process. As electric vehicles gain popularity, the user interface becomes pivotal in BMS development. Ensuring a user-friendly interface for monitoring and interaction is crucial for enhancing the overall user experience in the growing electric vehicle market, annotates Amitabh.

Hala MobilitySrikanth perceives the development of a BMS is not without its challenges. One of the primary challenges is achieving a delicate balance between optimizing performance and ensuring the safety of the battery pack. Additionally, addressing the diverse range of battery chemistries and configurations in the market poses a significant challenge. Hala Mobility’s approach involves continuous research and development to overcome these hurdles, staying at the forefront of BMS innovation.

Atul comments on how BMS designers face challenges such as precise cell balancing to ensure uniform performance, addressing thermal management for temperature control, and establishing reliable communication protocols. Achieving accurate state-of-charge estimation proves challenging due to cell variations and aging effects. Developing fail-safe mechanisms and ensuring compatibility with various battery chemistries add complexity. Moreover, striking a balance between high accuracy and cost-effectiveness presents a continual challenge. Addressing these issues requires a multidisciplinary approach, integrating electronics, software, and thermal engineering to create a BMS that meets the stringent safety and performance requirements of electric vehicles.

Raghuveer explains that developing an effective BMS is a journey marked by challenges. One such challenge is achieving a delicate balance between maximizing energy density and ensuring battery longevity. In our development stages, we encountered scenarios where intricate calibration was required to cater to diverse environmental conditions. Overcoming these challenges demands innovative solutions, rigorous testing, and a commitment to pushing the boundaries of what’s achievable. One practical and consumer-oriented issue is matching the end user riding experience and still maintaining optimal battery health. Hence it requires a hell amount of real-life testing, which requires a patience approach towards development.

Illustrating some of the key challenges faced while developing a BMS, Rohit from Tresa Motors annotates the following,

  • Accuracy in SoC Estimation: Achieving precise State of Charge (SoC) estimation remains a persistent challenge. Factors such as battery aging, varying operating conditions, and non-linear characteristics make accurate SoC determination complex as they introduce non linearity and coupled physics. Designers must create algorithms that account for these variables to provide reliable information to the driver.
  • Cell Balancing and Uniformity: Maintaining uniformity among individual battery cells is crucial for maximizing energy capacity and extending battery life. However, ensuring consistent charging and discharging across all cells, especially in large battery packs, presents a challenge. Designers need to employ algorithms that dynamically adjust charging and discharging currents to equalize cell voltages and use cell characterization to incorporate cell grouping strategies based on similar characteristics to minimize variability.
  • Safety and Fault Tolerance: Implement redundant monitoring systems and develop robust fault detection algorithms. Designers need to include hardware-based safety mechanisms like fuses, relays, or contactors for rapid disconnection in emergencies. Besides, the BMS designer shall also integrate fault-tolerant designs and algorithms that enable safe operation even under faulty conditions.
  • Integration and Compatibility: Integrating the BMS with various vehicle systems while maintaining compatibility with different battery chemistries and configurations presents a challenge. Ensuring seamless communication between the BMS and other vehicle components, as well as standardization across different EV models, requires careful design considerations.
  • Cost and Weight Optimization: Balancing the BMS’s cost and weight without compromising performance is critical. Designers face the challenge of implementing advanced functionalities while keeping manufacturing costs reasonable and minimizing the system’s weight to maximize vehicle efficiency and range.

BMS Topologies Ensuring Longevity & Efficiency

According to Tata Technologies, BMS designers need to give weightage to factors such as cell characteristics, efficiency, balancing accuracy desired, vehicle attribute, cost-effectiveness, and complexity of the battery and strike a balance between them to arrive at a topology for the system that meets the application.

Some of the key topologies that we consider during the conceptual phase of the BMS design range from Passive Topology for applications that demand simple and cost-effective designs to topology that uses smart adaptive balancing algorithms for target applications that call for high efficiency, better battery performance, and extended battery life.

There are several topologies that Tata Technologies carefully considers and reviews along with the customer starting with the vehicle’s attributes, the architecture, the expected drive cycle, the expected lifetime, costs, etc to mutually arrive at a design that balances all the above.

Log9 Materials holds the same viewpoint that Balancing battery cells is indeed crucial for the overall performance and lifespan of a battery management system (BMS). The major balancing topologies are around Active balancing, passive balancing, capacitive balancing, hybrid balancing etc. We have tried our hands on both Active balancing and passive balancing.

While choosing a particular balancing method, we consider efficiency, cost, complexity, and compatibility with the specific battery chemistry.

From the perspective of Lime.ai, Battery cell balancing plays a pivotal role in extending battery life. Due to manufacturing variations, individual cells within a battery pack exhibit different capacities, leading to imbalances. To maximize the overall capacity of the battery pack, it is crucial to balance these cells. There are two balancing methods: active and passive balancing. Most of the BMS works on passive balancing strategies since they are more effective and economical to implement.

Each balancing method can be achieved using two strategies: voltage-based balancing and SOC-based balancing. While most BMS systems employ voltage-based balancing, Lime has adopted SOC-based balancing to ensure accurate SOC equalization across all cells. We are able to implement SOC-based balancing due to our in-house lab, which specializes in cell testing and modelling.

LFP cells, which dominate the battery market, exhibit a flat voltage curve between 30% and 70% SOC. In such cases, voltage-based balancing strategies prove ineffective and may even lead to inaccurate cell balancing. To address this challenge, Lime has developed a model-based BMS balancing approach that effectively extracts the full capacity of each cell, ensuring optimal battery performance and longevity.

RapteeRaptee elucidates, BMS employs efficient battery cell balancing through techniques like passive, active, or hybrid balancing. Some systems use individual cell balancing (distributed), leveraging precision control, while others utilize a singular circuit for the entire pack (centralized), which is a balance between complexity and effectiveness. These approaches, integrating various topologies, contribute to optimal battery performance, longevity, and energy efficiency in electric vehicles.

RXN Electric feels that Battery Cell Charge Balancing is a pivotal function of any Battery Management System (BMS), crucial for the efficiency and longevity of electric vehicle systems. While conventional Chinese BMS typically balance cells only during charging, leaving imbalances during discharging, RXN BMS employs the innovative Curve Traced Passive Balancing algorithm. This pioneering approach ensures continuous cell balancing even during discharging, mitigating the accumulation of imbalances throughout the entire discharge cycle. This breakthrough in BMS design represents a significant stride towards sustained efficiency and prolonged lifespan in electric vehicle battery packs, emphasizing the importance of adopting innovative topologies in advancing the industry towards a more sustainable future.

Altigreen validates that in making sure batteries work well, it’s important to balance how much charge each part gets active balancing, cell connected in series to form a battery pack maintained to be equal to achieve the maximum efficiency of the battery pack.

Efficient charge balancing is fundamental to the longevity and performance of electric vehicle batteries. Our BMS employs advanced topologies to ensure that each battery cell operates optimally. This includes active and passive balancing techniques, ensuring that cells are uniformly charged and discharged. By adopting these topologies, we enhance the overall efficiency and extend the life of the entire battery system, explains Hala Mobility.

At e-Sprinto, our Battery Management System (BMS) employs advanced topologies to ensure efficient Battery Cell Charge Balancing, contributing to system longevity. We implement a Passive Balancing approach, utilizing resistors to equalize cell voltages during charging. This method enhances efficiency and extends battery life. Additionally, our BMS incorporates Active Balancing, employing switches and energy transfer to redistribute charge among cells, addressing any voltage discrepancies.

Charge balancing is paramount for the efficiency and longevity of the battery system. Our BMS incorporates sophisticated topologies, such as active balancing, which intelligently redistributes charge among individual cells. By doing so, it not only ensures optimal performance but also extends the lifespan of the battery, providing users with a reliable and enduring energy solution, justifies Aurita Bikes.

Tresa MotorsThe topology for Tresa Motors BMS is based on Master-Slave configuration with slaves arranged in a daisy chain configuration. Inside the battery pack, the smallest repeating unit of a group of parallel cells is called a brick. A finite number of these bricks connected in series, say a string now, are allotted to one slave. Allotment includes connecting voltage monitoring harnesses and temperature monitoring harnesses between the slave and its corresponding string of cell bricks. Similarly, the whole battery pack is interpreted into strings and different strings are assigned different slaves. All these slaves then communicate with one another and their common master through a defined communication protocol.

In case of multiple battery packs, multiple masters get involved. In that case, all these masters communicate with each other when supervised by a superior software algorithm. This software can be a standalone component or integrated with other embedded hardware as well. The decisions at the powertrain level are taken by this superior algorithm and further sent to the masters of the different battery packs.

Differentiation in BMS Solutions & Expansion Plans

Tata Technologies as an ESP has worked with OEMs globally, right from start-ups to established ones, right from the conceptual phase, systems engineering of the BMS, to writing application software in Matlab, Simulink, Embedded C/C++ to configuring the base layers to validating the BMS on a test bench, in the HIL environment, testing at the vehicle level and integrating the final BMS with the rest of the vehicle.

Tata Technologies has conceptualized a tool called EVSIM to simulate the charge balance needed based on the loads during different drive conditions. The tool predicts the charge balance based on the loads for various drive cycles. The tool helps in reducing the test costs and also speeds up the design. The tool helps in suggesting the optimal battery size too.

Tata Technologies is now planning to enhance the tool by building an ML model to capture and analyze real-time data in order to examine and improve the BMS design for the future. The ML model also has the prognostic capability to send alerts for preventive maintenance.

Log9 BMS is cell chemistry agnostic, compact & specifically developed for power applications, with added safety that is required for managing high C-rate charge & discharge cell chemistries. Another important feature for the log9 BMS is the algorithms like SoC, SoP, SoH, DTE, TTC estimations etc. that we have developed for all major Lithium-ion cell chemistries.

The advantage of log 9 BMS is that we have full control of the hardware, software & algorithms which was designed considering Indian climatic conditions for extreme fast charging & peak load applications to accommodate variable charge & discharge currents.

Few other features of the BMS are as follows: –

  • Robust logic for circuit protection
  • Higher Active balancing current
  • High power BMS designed for safe handling of higher currents & low thermal impacts.
  • Low Power BMS specifically designed to controls the outgoing & incoming power of the battery system.
  • Onboard advance protection features for failure detection.
  • Onboard battery protection for mitigating self-discharge of the battery pack in Ideal conditions.
  • Inbuilt over the cloud download and update capabilities.

The next version will have digital twin model to make impactful data-driven decisions based on state estimation regression model & fault diagnosis.

Lime‘s Battery Management System (BMS) stands out from its competitors in several key aspects. Backed by over eight years of experience and extensive data from monitoring over 50,000 battery packs, Lime’s BMS is meticulously tested and validated. Our team has dedicated countless hours to cell modelling and gaining a deep understanding of battery pack behaviour in our labs. This expertise has enabled us to develop advanced state-of-charge (SOC) and state-of-health (SOH) algorithms with a prediction error of less than 2%, ensuring exceptional battery performance and longevity.

Lime’s BMS transcends the realm of mere hardware, extending its capabilities into the cloud. Our cloud-based BMS seamlessly integrates with Lime’s IoT monitors, harnessing real-time data to proactively predict potential battery pack issues. This predictive maintenance approach enables us to optimize battery pack performance, slow down degradation, and extend residual useful life (RUL).

Currently, our focus lies in the EV 2-3-Wheeler markets. However, we have ambitious plans to expand our portfolio in the near future, encompassing energy storage systems and high-current and voltage-demanding BMS applications. Our vision is to create a comprehensive, one-stop solution for all battery management requirements, encompassing a vast array of battery types and applications.

Raptee’s Battery Management System is made for high-voltage system in electric 2-wheeler motorcycles, with smart safety features to preserve cell health over time. Through clever algorithms, temperature mapping, dynamic cell monitoring, precise control over charging and discharging processes, we ensure reliable performance, longevity, and efficiency for electric vehicle power system.

RXN Electric RXN BMS sets itself apart in the competitive landscape of Battery Management Systems (BMS) with a reputation for reliability and innovation. Distinguished by features such as a positive terminal switch, high transient immunity, and remarkable accuracy up to 1mV, RXN BMS ensures excellent performance in challenging conditions. Moreover, its competitive pricing, comparable to Chinese counterparts, underscores a commitment to providing cost-effective solutions without compromising on quality.

Committed to customer satisfaction, RXN BMS currently serves clients in key metropolitan areas across India and retails its products on major e-commerce platforms like Amazon and Flipkart. With strategic plans for expansion in the near future, the company aims to reach new markets and broaden its customer base, solidifying its position as a leader in the dynamic and evolving field of BMS technology.

Altigreen’s battery packs are regarded as advanced superior to the competition for several reasons:

  • Energy Density: Altigreen’s battery packs typically have high energy density, meaning they can store more energy in a given volume or weight. This allows the vehicle to achieve longer electric range without significantly increasing the size or weight of the battery pack as well as contributes to improved vehicle performance and efficiency.
  • Battery Management System (BMS): Altigreen has developed advanced battery management systems (BMS) that monitor and optimize the performance of our battery packs. The BMS ensures that the cells within the battery pack are balanced, protected from overcharging or overheating, and operating within their optimal range. This helps prolong the battery’s lifespan and ensures its safety and reliability.
  • Scalability and Modular Design: Altigreen’s battery packs are designed to be scalable and modular, allowing for different configurations to suit various vehicle models and customer needs. This flexibility enables Altigreen to offer different battery pack options with varying capacities and performance levels.

The Altigreen BMS is a Lithium-ion Phosphate battery management system that is specifically designed to meet the tough requirements of protecting and managing battery packs in our electric vehicles. It includes advanced features such as current & voltage protection that protects the battery pack from over-voltage and over-discharged thereby extending the cycle life of the battery. Thermal protection for over- and under-temperature protection, intelligent cell balancing for efficient passive balancing to maximize the usable capacity of the battery packs. It also monitors the health of the battery by monitoring internal resistance of the individual cells and the capacity of the battery pack.

The battery pack is operated with a BMS that is designed specifically to provide battery safety and protection to prevent any thermal run away and catching on fire. In addition, Altigreen’s battery pack includes built-in pressure relief valve or pressure vents so that any gaseous leak from the cells and subsequent pressure built up inside the battery pack can be released, thus protecting the battery pack from exploding and catching on fire.

Hala Mobility’s BMS solutions stand out in the market due to our unwavering commitment to innovation, safety, and performance. It is designed with a focus on adaptability, supporting a wide range of battery chemistries and configurations.

We differentiate ourselves by offering comprehensive, customizable solutions that cater to the unique needs of our clients. As we look to the future, we are actively exploring opportunities for further R&D, expansion, with plans to introduce advanced BMS technologies that will further revolutionize the electric mobility landscape, across India.

e-Sprintoe-Sprinto’s BMS solutions stands out from competitors through its innovative dual approach to Battery Cell Charge Balancing, combining Passive and Active Balancing for optimal efficiency. Our BMS prioritizes precision in cell monitoring, robust fail-safe mechanisms, and seamless communication protocols. Looking ahead, e-Sprinto plans to expand its BMS capabilities by exploring advanced algorithms for state-of-charge estimation and incorporating emerging technologies to further enhance the safety, performance, and overall user experience of our electric two-wheelers. Continuous innovation remains at the forefront of our strategy for the future.

What sets Aurita Bikes’ BMS solutions apart is a fusion of innovation and adaptability. For example, we are actively exploring the integration of machine learning algorithms into our BMS, which would dynamically adjust parameters based on real-time usage patterns. This forward-looking approach, coupled with our commitment to continuous improvement, positions us uniquely in the market. As for expansion, we are in talks with potential partners and considering strategic collaborations to amplify our impact and contribute to the global shift toward sustainable mobility.

As rider experience varies with respect to the type of vehicle, and location (terrains), we are working with multiple partners in optimising battery performance and in turn the cost per km for the end user. We envision launching more sophisticated IoT enabled battery packs in the coming months that can adapt to rider behaviors.

Tresa Motors’ BMS possesses the capability to simultaneously measure each cell reading using 2 dedicated ADCs for every series link, ensuring increased redundancy and swifter readings. With different dedicated ADCs and a hardware-accelerated Overcurrent Protection System, critical operation timelines are significantly improved. External sensors specifically monitoring cell temperatures augment reliability and significantly improve the chances of early detection in scenarios involving thermal runaway. Our objective is to engineer one of the most resilient BMS systems, placing utmost emphasis on safety, particularly for high-capacity packs.

In our upcoming strategies, the concept of parallelizing packs for modularity represents an advanced design approach. This pioneering concept enables seamless operation and cooperation among individual packs. Additionally, gathering comprehensive cell voltage, temperature, and assorted pack data, and transferring it to the cloud, coupled with feedback loops empowered by machine learning algorithms, guarantees a comprehensive understanding of battery behaviors across varying environmental conditions, applications, and terrains. This method significantly enhances battery status estimation, extends battery longevity, and minimizes the likelihood of fire accidents.

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