Diagnostic infrastructure for the battery circular economy
Mentha builds edge AI diagnostic systems for second-life lithium-ion batteries. We replace multi-hour cycling tests with electrochemical impedance measurements that run in seconds on edge hardware — purpose-built for battery repurposers preparing for the EU Battery Passport.
The problem
When an electric vehicle battery reaches the end of its first life, it typically retains 70–80% of its original capacity. Repurposing that battery into a stationary storage system can extend its useful life by another decade — but only if the operator can verify its current state of health, internal resistance, and self-discharge behaviour.
Today, that verification follows UL 1974 procedures: manual charge and discharge cycles, direct current resistance measurements, and capacity tests that take five to eight hours of skilled labour per module. Recent peer-reviewed analysis puts testing costs at €57 per kilowatt-hour — a meaningful share of the module’s residual commercial value.
From February 2027, every electric vehicle, light electric vehicle, and industrial battery above 2 kWh placed on the EU market must carry a Battery Passport with current dynamic state-of-health attributes. Every repurposed module needs a new passport. The existing testing infrastructure cannot meet that demand at cost.
What we're building
Our system applies a small-amplitude excitation signal to a battery module and measures its frequency-domain response. The resulting Nyquist spectrum captures internal resistance, charge-transfer dynamics, and diffusion behaviour in seconds — the same physics used in research labs, deployable at intake.
A compressed neural network runs on dedicated edge hardware to translate impedance spectra into state-of-health, internal resistance, and self-discharge estimates. No cloud round-trip. No vendor lock-in. Results in under five milliseconds per inference, on a device that costs less than the labour it replaces.
Output maps directly to the dynamic data attributes required by Regulation (EU) 2023/1542 — remaining capacity, internal resistance increase, self-discharge evolution, and state-of-health. One measurement, passport-ready data, no manual transcription.
Why now
From 18 February 2027, every battery in scope of the EU Battery Regulation must carry a digital passport with dynamic state-of-health data. Repurposers issue a new passport every time a module is placed on the second-life market. Independent, fast, edge-deployed measurement is the only way to feed this regime at industrial scale.
The market is small enough today that the right diagnostic infrastructure can be designed in close partnership with the repurposers who will define it. That window is open for the next eighteen months. We're building during it.
Where we are
We have a working diagnostic pipeline from impedance acquisition through edge inference to passport-ready output. Current validation programme focuses on benchmarking measurement accuracy on second-life automotive battery modules across NMC and LFP chemistries.
How we work
Our diagnostic system sits on your intake bench, not in a remote lab. Modules are tested where they arrive, by your operators, using a workflow built around your existing throughput — no shipping, no batch delays, no cold-chain logistics.
We don't ask you to absorb the cost of test equipment before you've seen the value. The commercial model is built around measurements completed and passports issued. When you don't test, you don't pay.
Inference runs locally on edge hardware. Measurement records, module identifiers, and customer information remain within your network unless you choose to share them. We support whatever data residency posture your supply chain requires.
Every measurement produces the dynamic data fields required by Regulation (EU) 2023/1542 in a structured format. When the Battery Passport becomes mandatory in February 2027, the integration with your passport system is already done.
We are working with a small number of design partners through 2026 to shape how this works in practice. If you operate a second-life facility, we’d like to talk early.
Get in touch
We're talking to second-life battery operators, integrators, and OEM partners across the UK and Europe. If you're preparing for the Battery Passport, working on testing automation, or thinking about how diagnostic data should flow through your supply chain, the conversation is worth having.
info@menthaenergy.com