EV Battery Management Systems: Modular Innovation for a Sustainable Future

High-energy NMC cells necessitate smaller form factors due to safety considerations, making them ideal for modular configurations.

January 14, 2025. By News Bureau

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articles

EV Battery Management Systems

BorgWarner

Electric Vehicles

EV Technology

Battery Management Systems

Sustainable future

Johannes Rossmanith

The rapid evolution of electric vehicle (EV) technology has brought significant advancements in battery management systems (BMS) and battery design. As the core unit of any EV, the battery and specifically its architecture plays a critical role in determining performance, safety, and sustainability. While trends like cell-to-pack (CTP) technology aim to increase energy density by eliminating traditional modules and therefore, components that do not contribute to the energy storage, modular battery systems retain key advantages that ensure their relevance in the dynamic e-mobility landscape.

The Case for Modular Batteries
Modular battery systems offer unparalleled flexibility. By organising smaller cells into modules, manufacturers create adaptable building blocks with high functional integration, facilitating custom configurations to suit varying applications. For instance, BorgWarner’s Gen3 NMC (Nickel Manganese Cobalt) solution utilises 21700 cylindrical cells to create modules that integrate the key functions of energy storage like sensing and balancing, liquid cooling, safety functions and structural strength. This modular approach allows for the development of scalable packs, such as the 9 AKM CYC system with up to 100 kWh, which can be adjusted by adding or removing modules.

Furthermore, modularity supports sustainability. Modules act as intermediate building blocks that encourage reversible installation methods, reducing reliance on adhesives and potting. This design consideration enhances the feasibility of remanufacturing and recycling, which are increasingly vital in a world prioritising environmental responsibility.

Evolving Industry Perspectives
The industry is simultaneously pursuing modularity and larger cell formats through innovative approaches like CTP design. BorgWarner’s new LFP (Lithium Iron Phosphate) battery family demonstrates this balance. Utilising large blade cells, and making use of the intrinsically higher safety of the LFP chemistry, these systems incorporate defined cell stacks to create multiple pack geometries tailored to various vehicle types, from buses to off-road machinery. The result is a modular approach within a CTP framework, enhancing efficiency in development and production, being even able to produce different form factors like flat, high, cubic and compact packs on the same line.

This convergence of modularity and cell innovation reflects the industry’s drive for solutions that balance energy content, cost-efficiency, and application coverage. Commercial vehicles, in particular, benefit from such flexibility, given their diverse operation and space demands and the imperative for cost parity with diesel-powered alternatives especially considering the total cost of ownership (TCO).

Engineering Trade-Offs and Innovations
Designing battery modules involves intricate trade-offs. Modules add structural components and occupy space, which can slightly reduce overall energy density compared to CTP systems. However, this trade-off is offset by the advantages of modularity, such as easier integration of advanced sensing and thermal management technologies.

For instance, BorgWarner’s Gen3 NMC modules combine mechanical stability and cooling within a single extruded profile, serving as the backbone of the module and contributing to the pack’s structural strength. This integration minimises parts while simplifying pack assembly and scalability. Similarly, in the LFP blade cell systems, cooling solutions are streamlined to a single cooling plate as an integral housing component and by placing connections outside the tray, reducing internal complexity and enhancing efficiency.

Safety remains a paramount concern in module design. BorgWarner incorporates multi-level safety mechanisms, from cell-level features like pressure-activated current interrupt devices to module-level thermal propagation barriers. These measures ensure robust performance across a range of applications, from light commercial vehicles to heavy-duty trucks.

Impact of Cell Chemistry on Module Design
Cell chemistry profoundly influences module architecture. High-energy NMC cells necessitate smaller form factors due to safety considerations, making them ideal for modular configurations. In contrast, LFP cells, with their intrinsic safety and cost advantages, enable larger cell sizes and favour CTP designs. However, even in LFP systems, modular concepts persist, particularly where scalability and application versatility are critical.
The blade cell’s innovative design exemplifies this synergy. Its long, narrow shape enhances structural stability and energy density at the pack level, overcoming the traditional disadvantages of LFP chemistry. This positions LFP systems as highly scalable solutions for diverse vehicle architectures, from light commercial vehicles to marine applications.

BMS: The Backbone of Battery Systems
Advances in BMS technology are enabling more precise control over battery performance. Modular systems with fewer cells simplify the electronic design to ensure individual cell monitoring and to improve algorithms for state-of-charge and health predictions. In simple terms, analysing an array of fewer cells with less complex serial or parallel configuration improves single cell analysis and helps to become more accurate in SOx (state of x=health, charge, …) and enables more advanced analysis technologies like electrochemical impedance spectroscopy and other transient methods. The software and hardware solutions are already instrumental and will become even more critical in enhancing the safe and sustainable use of the cells and boosting efficiency in energy utilisation.

BorgWarner’s advanced modular hardware and software platform exemplifies this evolution. The distributed system ensures effective and optimised sensing of single cell (LFP CTP) and cell cluster (NMC modules) with high accuracy and simulation-backed efficiency. Modular software and high computing power allow for advanced and always up-to-date algorithms. By supporting seamless integration and compliance with cybersecurity and regulatory standards, it empowers customers to achieve maximum efficiency in diverse applications.

The Future of Modular Batteries
Looking ahead, modular battery technologies will stay relevant in response to industry demands for sustainability and versatility. While larger cells and CTP designs show clear cost, energy- and power-density benefits, potential shifts in cell chemistry, such as all-solid-state batteries, could drive renewed interest in highly modular systems.

For now, the balance between modularity and innovation is epitomised by solutions like BorgWarner’s Gen3 NMC and LFP systems. These technologies demonstrate that thoughtful engineering can address the complex trade-offs of energy density, safety, and flexibility, ensuring that EVs remain competitive and sustainable across a wide range of applications.

By embracing modular design principles alongside cutting-edge advancements, the industry is not only optimising EV performance but also paving the way for a greener, more adaptable transportation future.

- Johannes Rossmanith, Director - R&D, Battery Systems, BorgWarner