Ecodesigned modular electric vehicle battery set for second-life use

The European MARBEL project, coordinated by the Eurecat Technology Center, has developed a new battery concept for electric vehicles, focusing on large-scale modular and eco-design principles. The implementation of this approach reduces environmental impact and promotes the circular economy within the automotive industry.

The prototypes’ eco-design centered on making battery components easy to assemble and disassemble, directly improving repair efficiency, reuse in other applications, and recyclability. To achieve this, the developed battery packs incorporate up to 60 percent of post-consumer recycled aluminum—equating to a savings of up to 777 kg of CO₂ emissions per pack—and prioritized the modularity to increase the battery and its components' lifespan, reducing waste and environmental impact.

Additionally, the prototypes introduce innovations for ultra-fast charging by implementing a cooling system design that ensures uniform heat removal from the cells and busbars, combined with optimization algorithms for the charging process. A switchable Junction Box has also been added to support flexible battery architecture, allowing seamless transitions between 400 and 800 volts and vice versa depending on requirements supporting modularity for both smaller and larger battery packs.

The eVIL platform introduces an advanced hardware-in-the-loop (HiL) testing environment to validate the integration and performance of EV powertrain components — including the battery pack, e-motor, inverter, and auxiliary systems — under highly realistic, controllable conditions. Developed around Applus+ IDIADA's state-of-the-art battery and e-motor test benches, the platform simulates complete driving and environmental scenarios (e.g., WLTP cycle, ambient temperatures from –40°C to +75°C), enabling real-time evaluation of system behavior without needing a full vehicle prototype. The platform is built to test real-world interactions between battery dynamics, thermal behavior, and vehicle control strategies, making it an ideal validation tool for both early-stage R&D and pre-production system integration. The advanced testing equipment and the innovative eVIL concept represent a significant technological achievement and a valuable outcome of the project.

“The focus on circularity creates a pathway to more sustainable electric vehicle technology. At the same time, by optimizing battery performance, we address the main hurdles that hinder electric vehicles’ acceptance and adoption, such as limited range and lengthy charging times, enabling longer trips,” says MARBEL Project Coordinator Eduard Piqueras, European Program Manager at Eurecat.

Second life for batteries and end of life

A key element tackled by the MARBEL project has been to extend battery life through second-life applications, enabling their reuse, recyclability, and refurbishment for energy solutions beyond automotive purposes.

“By integrating eco-design principles such as modularity, second-life applications, and materials with a high percentage of recycled content, MARBEL has extended battery usage while maintaining material value, effectively reducing waste and advancing both sustainability and economic viability,” explains Violeta Vargas, researcher in Eurecat’s Waste, Energy, and Environmental Impact Unit.

MARBEL has also integrated advanced materials’ recovery strategies to reclaim high-purity graphite, lithium, nickel, manganese, and cobalt of the end-of-life cells, complying with the European Regulation on “Sustainability Rules for Batteries and Waste Batteries”.

Smart architecture

The prototypes developed feature an intelligent architecture that use busbars for power connections. These busbars can be easily assembled and disassembled with standard screwed fasteners, and their flexible formats have been refined to simplify assembly operations and withstand potential vibrations in the vehicle’s battery pack.

Moreover, the Battery Management System (BMS) includes wireless communications and real-time smart energy monitoring, significantly reducing weight, cost, and design complexity. Specifically, an intelligent electronic device (iSCM – intelligent Smart Cell Manager) has been developed for each battery cell, allowing local cell monitoring and direct communication with the BMS through Bluetooth technology.

For instance, in a 16-cell battery pack, wiring can be reduced from more than 20 meters to just 80 centimeters, lowering material costs, weight, and assembly complexity, while enhancing overall efficiency.

Data collected by the BMS, together with information generated by the iSCM, is fed into a digital twin driven by artificial intelligence and machine learning algorithms, enabling predictive analytics by combining multiple data sources in a single web-based application. The system can predict remaining battery life, state of charge and health, and estimate when the battery will reach the end of its lifespan, among other key parameters. This allows for the availability of reliable information to plan a second useful life based on the health status of the components.

The project has received funding from the European Union’s Horizon 2020 program. The MARBEL consortium includes 16 partners across eight countries: six universities and research centers (Eurecat, project coordinator; the Catalonia Institute for Energy Research (IREC); SINTEF; ICCS at the National Technical University of Athens; Technische Hochschule Ingolstadt; and Fraunhofer IWU), one automotive engineering company (Applus IDIADA), two SMEs (Powertech Systems and OTC Engineering), one OEM (Stellantis – CRF), and five component manufacturers (FICOSA, AVL Thermal HVAC, AVL Italia, ASAS, Agrati, and SK Tes).

The MARBEL project has received funding from the European Union's H2020 research and innovation program under grant agreement No. 963540.