Interview with Kobe Fleerackers, Senior System Development Enginer at Watt4Ever

In this interview, Kobe Fleerackers, Senior System Development Engineer at Watt4Ever, an industrial partner within the HiHELIOS and part of the Sortbat Group, shares insights into the company’s role in advancing hybrid energy storage systems and its impact within HiHELIOS. Watt4Ever brings strong hands-on expertise in the reuse and repurposing of second-life EV battery modules, along with extensive experience in the design, build and testing of custom battery energy storage systems. Within HiHELIOS, the company focuses on integrating repurposed EV batteries into hybrid storage architectures, contributing to modular, application-specific solutions that combine different technologies and chemistries in a smart and efficient way. Through this work, Watt4Ever helps bridge sustainability, performance and industrial feasibility, supporting the project’s ambition to develop scalable and future-ready energy storage solutions for Europe’s energy transition.

Watt4Ever is a key industrial partner in HiHELIOS. Could you briefly introduce your company and explain your specific role within the project?

Watt4Ever, part of the Sortbat Group, specializes in giving electric vehicle batteries a valuable second life. We commercialize battery modules and cells recovered from EV batteries for second-life applications and use them to develop and build custom battery systems, primarily for energy storage applications. In doing so, we contribute to a more efficient and sustainable lifecycle for used EV batteries while delivering practical solutions that support the energy transition.

As Senior System Development Engineer at Watt4Ever, I am responsible for the development, production, and testing of new battery energy storage systems, as well as custom battery solutions tailored to client needs. Within HiHELIOS, I coordinate Watt4Ever’s contribution to the project, lead our engineering team, and support the key technical decisions behind the design of the various hybrid energy storage systems. Our role is to translate the project’s ambitions into robust, application-specific storage solutions that can ultimately be manufactured to high industrial standards.

HiHELIOS aims to develop advanced hybrid energy storage systems. How does Watt4Ever’s expertise in second-life EV batteries contribute to achieving this ambition?

Watt4Ever brings strong hands-on expertise in the reuse and repurposing of second-life EV battery modules, combined with practical experience in the design, development, and testing of custom battery energy storage systems. This combination is highly relevant to HiHELIOS, because hybrid energy storage is not simply about combining new and second-life batteries, but also about intelligently integrating different technologies and chemistries within a single system.

This is where second-life batteries can make a meaningful contribution. Their high-energy characteristics are particularly well suited for longer-duration storage, while complementary high-power technologies within the hybrid energy storage system (HESS) can provide rapid power bursts when fast response times are required. In this way, hybridization allows each technology to operate where it performs best. For Watt4Ever, this represents a compelling model that creates strong synergy between sustainability, technical performance, and cost-efficient system design.

More broadly, our expertise is strengthened by the wider Sortbat Group, which covers the full second-life battery value chain — from safe collection and transport to repair, refurbishment, and repurposing. Within this ecosystem, Watt4Ever focuses specifically on testing, diagnostics, system integration, safety, and quality assurance, all of which are essential for extending battery lifetime and transforming second-life batteries into reliable industrial-grade products.

HiHELIOS brings together a diverse consortium of industrial and research partners. How has this collaboration influenced your work, and what added value does it create compared to working independently?

For us, one of the great strengths of HiHELIOS is exactly this diversity of the consortium. Bringing together industrial players, universities and research institutions from different countries and with different backgrounds creates a very strong learning environment. It allows us to challenge assumptions, compare perspectives and develop solutions that are more complete than what any one partner could achieve alone.

In practical terms, this collaboration has helped us refine the design of the HESS for each use case. At Watt4Ever, we started from different battery system proposals, based on several chemistries and both second-life and new batteries. Other partners then helped assess and select the most suitable combinations for each use case. That process creates real added value, because it ensures the final system architecture is not only technically sound, but also better aligned with the operational, economic and application-specific requirements of the project.

Compared with working independently, this kind of collaboration accelerates development and makes the result more relevant for the market. It helps us build not just a battery system, but a more integrated and future-proof energy solution.

What has been the most surprising or insightful lesson for Watt4Ever since joining the HiHELIOS project?

One of the most insightful lessons for Watt4Ever has been how much value can be unlocked by combining not only new and second-life batteries, but also different storage technologies or chemistries within one hybrid system.

Before a project like HiHELIOS, it is easy to think mainly in terms of a single battery technology optimized for one duty profile. What the project has really highlighted is that a hybrid approach can be much more powerful. By combining a high-energy component with a high-power component, you can create a system that stores energy efficiently over longer periods while also being able to deliver fast, short-duration power when needed. That flexibility is extremely important for real-life energy systems, where the demands are rarely one-dimensional.

For Watt4Ever, this has reinforced the idea that the future of storage is not about one technology replacing all others. It is about intelligently combining the strengths of different technologies, including second-life batteries, to build systems that are more efficient, more sustainable and better adapted to real operational needs.

How can the solutions developed in HiHELIOS be replicated or scaled across different regions and energy systems in Europe?

A key factor for replication and scaling is modularity. From Watt4Ever’s perspective, modular system design and adaptable control are essential, because they make it much easier to tailor a solution developed in HiHELIOS to new use cases, new customer needs and different energy system contexts across Europe.

That is especially important because scalability is not just about increasing size; it is about adapting intelligently. Different regions have different technical needs, market conditions and operational priorities. A modular HESS architecture makes it possible to reuse the same core design philosophy while adjusting the storage mix, control strategy or system configuration to local requirements.

At the same time, European competitiveness will also depend on more than cost alone. Competing only on price is extremely difficult, especially against suppliers from outside Europe. This is why we believe Europe must differentiate through quality, operational efficiency, strong technical support, safety and regulatory compliance. That is also where Watt4Ever sees its role: providing trusted second-life battery expertise and custom-designed battery systems that are not only innovative, but also reliable and ready for real deployment.