65 Modular batteries | Product focus E-Mobility Engineering | January/February 2025 optimising the structural integration of cells and modules. Advanced manufacturing techniques simplify assembly, reduce the parts count and enhance structural efficiency. The industry is also exploring hybrid approaches that combine modular principles with C-t-P elements. For instance, large-format cells can be grouped into stackable units that function like modules but offer the packing efficiency of C-t-P designs. This hybrid approach delivers the flexibility of modular systems while maximising energy density and minimising material costs. Applications beyond the automotive sector are increasingly driving innovation. Off-highway, heavy-duty and marine vehicles often require highly adaptable battery systems that are capable of enduring long operational lifetimes. In these sectors, repairability, scalability and future-proof design take precedence, making modular solutions an attractive choice. Smaller manufacturers or those without extensive in-house battery expertise are also benefitting from modular solutions in the form of ready-made systems that enable rapid electrification of existing platforms, bypassing the investment and time required to develop bespoke battery designs. As the market diversifies, modular systems continue to play a critical role in accelerating the adoption of e-mobility across various industries. Complex trade-offs Designing modular batteries involves navigating a complex matrix of engineering trade-offs. The key challenges revolve around balancing energy density, thermal management, cost and system complexity while maintaining safety and performance. The inclusion of modules inherently reduces the overall energy density of the battery pack. Modules add inactive material – such as enclosures, connectors and cooling infrastructure – that does not contribute to energy storage. This is a significant trade-off compared with C-t-P systems, where cells are packed more densely, maximising volumetric and gravimetric efficiency. Effective thermal management is critical for both safety and performance. Modular systems allow for the segregation of cells, which can help to contain thermal runaway events, but this segregation can increase weight and complexity, so cooling systems must be designed to dissipate heat efficiently without compromising energy density or structural integrity. Some systems are exploring immersion cooling or integrating liquid cooling channels within modules to improve thermal performance. Cost is a pervasive consideration in all battery designs. Modular systems typically involve more components and assembly steps than C-t-P designs, which can increase manufacturing costs. However, these costs can be offset by the economies of scale achievable with a standardised design system that allows for rapid adjustment of the module’s final design and cell configuration before committing to manufacture. Advanced automated Modules can be removed, refurbished or repurposed with relative ease, supporting re-manufacturing and recycling efforts. This reversibility reduces waste and enhances the environmental benefits of EV adoption. Modular systems also provide a serviceability advantage. In the event of a failure, specific modules can be replaced without discarding the entire battery pack. This reduces downtime for fleet operators and individual users alike, particularly in commercial applications where reliability is paramount. Furthermore, modular designs allow for the integration of diverse cell chemistries to suit different performance and cost priorities. Evolving role Design philosophy is evolving in response to industry demands for higher energy densities, reduced costs and improved manufacturability. Innovations in modularity aim to narrow the gap between the performance of modular systems and C-t-P designs. For instance, smarter module designs now achieve energy densities comparable to C-t-P systems by Customisable and scalable, Ricardo battery modules use Innobat pouch cells, with high specific energy and C rating. They are BMS-agnostic, but come with Ricardo’s BMS as standard (Image courtesy of Ricardo)
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