Second-Life Battery Packs: The Implementation Gap Between Policy Ambition and Operational Reality

In Brief

A new CEPS report identifies the core blockers preventing second-life electric vehicle batteries from scaling in Europe: unclear liability frameworks, inconsistent State of Health standards, weak demand signals, and manual repurposing processes that kill unit economics. The fix requires harmonized technical standards, clearer regulatory ownership rules, and funding for automation. Teams deploying second-life battery systems need to answer three questions before procurement: Who owns liability when the battery fails? What SoH threshold triggers rejection? How does the system handle module-level heterogeneity?

The gap between circular economy ambitions and operational deployment is exactly the kind of problem that keeps implementation teams awake. Europe's AI and energy transition leaders are gathering at Human x AI Europe on May 19 in Vienna to work through these system-level challenges together.

The Promise Sounds Simple. The Execution Isn't.

Electric vehicle batteries don't die at 80% capacity. They just become unsuitable for the high-performance demands of automotive applications. That remaining capacity, often 70-80% of original, could power residential storage, commercial backup systems, or grid-scale energy storage. The logic is compelling: extend battery service life, delay recycling, reduce mining pressure, lower costs for stationary storage.

The CEPS report published yesterday maps the European landscape for second-life battery applications and identifies why the market hasn't scaled despite years of pilot projects. The findings won't surprise anyone who has tried to move from demonstration to deployment: the technical challenges are solvable, but the policy, economic, and supply chain barriers remain formidable.

Four Domains of Failure

The CEPS analysis, produced under the EU's Horizon Europe-funded BATRAW project, organizes the challenges into four domains. Each one represents a different type of implementation risk.

Policy and Liability Uncertainty

Who owns responsibility when a repurposed battery fails? The original vehicle manufacturer? The repurposing company? The end user? The CEPS report recommends that the EU provide more clarity on the liability framework governing batteries entering repurposing pathways. Without this clarity, insurers price risk conservatively, and potential second-life operators hesitate to enter the market.

This isn't a theoretical concern. A battery that catches fire in a commercial building creates liability exposure that cascades through the entire value chain. Until the legal ownership of that risk is clearly assigned, the market will remain fragmented.

Technical Standardization Gaps

State of Health (SoH) and State of Charge (SoC) are the critical metrics for determining whether a battery is suitable for second-life applications. The problem: there's no harmonized approach to measuring or reporting these values across the EU.

Research published in Frontiers in Chemistry notes that the 80% SoH end-of-life criterion was originally established for nickel-cadmium batteries, not lithium-ion. Modern LiBs have far greater energy density (240-300 Wh/kg), power density (200-950 W/kg), and longer lifetimes (6-15 years) than their predecessors. The blanket 80% threshold may be overly conservative for some chemistries and applications while being too aggressive for others.

Battery analytics providers like ACCURE point out that Battery Management System (BMS) data from first-life applications is often unreliable and typically reports only system-level information when module-level data is actually required for proper assessment.

Economic Viability Constraints

The unit economics of second-life batteries depend heavily on repurposing costs. Manual disassembly, testing, and reconfiguration are labor-intensive. The CEPS report calls for EU-funded projects to continue supporting innovation in automation of repurposing processes to enable cost reductions.

ACEEE's 2025 policy brief identifies the core economic challenge: repurposers often purchase used EV batteries with little accompanying data from the automaker or first user. Without historical performance data, repurposers must conduct extensive testing to determine suitability, which drives up costs and reduces margins.

Supply Chain Complexity

The diversity of EV battery designs creates a fragmented supply chain for second-life applications. Different cell chemistries (NMC, LFP, NCA), form factors (cylindrical, pouch, prismatic), module configurations, and BMS architectures mean that repurposing facilities must handle enormous variety.

Research from RWTH Aachen emphasizes that depending on the cell manufacturer and EV model, batteries differ in cell chemistry, cell type, module dimension, power, capacity, refrigeration system, BMS, and functional characteristics. This makes it impossible to develop a unified technical procedure for screening and assessment.

The Battery Passport: Necessary but Not Sufficient

The EU's planned battery passport, a digital information repository tracking battery lifecycle data, addresses some of these challenges. Research from the University of York and Norwegian University of Science and Technology examines the potential applications and challenges of battery passports for second-life systems.

The passport concept would provide transparency on manufacturing data, usage history, and recycling recommendations. For repurposers, access to first-life operational data (voltage, current, temperature profiles) would dramatically improve the accuracy of SoH assessments and reduce testing costs.

But the passport alone doesn't solve the liability question, doesn't create demand for second-life systems, and doesn't automate the physical repurposing process. It's an enabler, not a solution.

What Implementation Teams Need to Know

For organizations considering second-life battery deployments, the CEPS report and supporting research suggest a practical checklist:

Before procurement, answer these questions:

• What is the documented SoH threshold for acceptance, and how was it measured?
• Who holds liability for thermal events or performance failures?
• What module-level data is available from first-life operation?
• How will heterogeneity between modules be managed in the system design?
• What is the rollback plan if the system underperforms?

For policymakers and procurement officers:

The CEPS recommendations point toward three priority areas: clarifying liability frameworks, harmonizing SoH/SoC measurement standards, and funding automation R&D. The U.S. Department of Energy's Bipartisan Infrastructure Law has already allocated $73.9 million to battery recycling and second-life demonstration projects, including Element Energy's MW-scale second-use battery storage system in Texas. Europe needs comparable investment in scaling proven approaches.

The Uncomfortable Truth

Second-life battery applications make environmental and economic sense. The technology works. Pilot projects have demonstrated feasibility. But the market hasn't scaled because the implementation infrastructure, the standards, the liability frameworks, the data sharing protocols, the automated processing systems, doesn't exist at commercial scale.

This is a systems problem, not a technology problem. And systems problems require coordinated action across policy, industry, and technical domains. The CEPS report provides a roadmap. The question is whether European stakeholders will execute on it before the wave of end-of-life EV batteries arrives in force.

By 2030, projections suggest up to 120 GWh/year of untapped capacity stored in end-of-life batteries. That's either a massive resource or a massive waste stream. The difference depends entirely on implementation.