66 design tools further reduce costs by accelerating the design process and minimising manual iteration. The serviceability of modular systems is a major advantage, but introduces its own challenges. Engineers must ensure modules can be removed and replaced easily without compromising the structural integrity of the pack. This often requires additional design elements, such as reinforced housings or accessible interfaces, which add weight and complexity. Balancing these requirements with the demand for lightweight, compact designs is a constant challenge. Safety remains paramount in all battery designs, and modular systems are no exception. Engineers must carefully consider how to isolate and protect cells within a module to prevent cascading failures in the event of a thermal incident. The structural design of the module plays a crucial role in this regard, providing containment while ensuring heat and gases can be vented safely. While modular systems excel in scalability, achieving optimal performance often requires customisation. Applications with specific power or energy requirements may demand tailored configurations, which can increase development time and cost. Engineers must weigh the benefits of a standardised, modular approach against the potential gains of bespoke designs. The evolution of modular battery technology for EVs is marked by diverse innovations in packaging, thermal management and electronics integration. As energy density approaches the theoretical limits for current chemistries, efforts are increasingly being focused on refining the way battery cells are organised into modules, offering flexibility, safety and cost-effectiveness. Engineers in the EV industry are navigating a rapidly maturing landscape where technology and economic pressures are shaping module design. Designs on flexibility The integration of modularity within battery systems plays a crucial role in balancing the demands of diverse vehicle applications, from buses and trucks to offroad vehicles. Modular designs enable manufacturers to use a combination of different cell chemistries and form factors within the same platform, although this has not yet become common practice. For instance, prismatic lithiumion phosphate (LFP) cells, known for their safety and stability, can be integrated alongside cylindrical cells, which may use higher energy-density nickel manganese cobalt oxide (NMC) chemistries, potentially offering a range of options tailored to energy content, lifespan and total cost of ownership. The adoption of modular hardware and software architectures allows seamless integration across applications, supporting compliance with regulations and cybersecurity standards. This adaptability helps manufacturers address cost constraints while maintaining high quality and performance. They can achieve economies of scale, even in lowervolume applications, enabling the EV sector to compete with the cost structures of diesel vehicles. Thermal management Thermal management remains a cornerstone of modular battery design and multiple factors affect it. One is cell form factor, with smaller, cylindrical cells potentially offering better cooling efficiency, while larger, prismatic and pouch cells sometimes complicate cooling and need structural allowances for swelling. However, the impact of cell form factor on thermal management must be considered alongside cell specifications, other specific applications and battery pack design. Innovative materials and structural designs are being developed to address these challenges. Lightweight polymer composites are increasingly replacing metal casings to reduce weight while maintaining robustness. Simplified internal wiring and fewer welds also enhance thermal stability by minimising heat generation at electrical connections. Also, C-t-P and cell-to-chassis architectures free up space for thermal management hardware. Cell-to-pack limitations The push towards C-t-P architectures brings a number of advantages over modular designs in some applications. By eliminating intermediate module structures, this approach Product focus | Modular batteries January/February 2025 | E-Mobility Engineering Exploded view of Ricardo’s flexible battery module, designed to meet the challenges facing OEMs in low-volume manufacturing (Image courtesy of Ricardo)
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