Battery Second Life and the Passport

A battery leaving its first application with meaningful capacity remaining is either an asset or a disposal cost, and which one it is depends almost entirely on how cheaply its condition can be established.

Second life is the practice of repurposing such a battery into a less demanding application, typically stationary storage. Regulation (EU) 2023/1542 addresses it directly, and the legal consequence surprises most people encountering it for the first time.

Repurposing creates a new obligation

Preparing a battery for repurposing and placing it on the market for a different application is treated as placing a new product on the market. The party doing so becomes an economic operator with the obligations that carries.

That means conformity assessment for the new application, a new passport reflecting the repurposed product, and responsibility for the safety and performance claims made about it. The original manufacturer’s obligations do not transfer to cover the second life.

The first row is why the original passport has to remain reachable. A repurposer cannot restate chemistry and construction facts they did not observe, so they depend on the record the manufacturer published years earlier.

Grading is the whole economic question

The value difference between a battery worth repurposing and one worth shredding is substantial, and establishing which is which costs money.

Physical testing of a used pack — cycling it to measure capacity, checking cell balance, assessing internal resistance — takes hours of equipment time per unit. For packs with modest residual value that assessment can exceed the value it establishes.

What has to carry across

The repurposer needs a specific subset of the original record, and it is not the same subset a recycler needs.

• Chemistry and cell configuration — determines what the pack can safely be used for and how it must be managed.
• Rated capacity and original performance — the baseline against which remaining capacity is expressed.
• State of health history — a trend rather than a single reading, because the degradation curve predicts remaining life.
• Fault and service history — a pack with a thermal event in its history is a different proposition from one without.
• Dismantling and safe handling — because repurposing usually involves opening the pack.

The third item is the one most often unavailable. A single current state of health reading tells a repurposer the present condition; a history tells them how fast it is degrading, which is what determines whether the second application is viable for its intended duration.

The applications that work

Second life succeeds where the new application is genuinely less demanding across the dimensions that degraded, which is a narrower condition than it first appears.

Stationary storage tolerates reduced energy density and reduced power, because neither weight nor acceleration matters. It tolerates reduced capacity because more modules can be added. It does not tolerate unpredictable failure, which is why cell imbalance rather than capacity fade is usually what rules a pack out.

Why manufacturers should care

A manufacturer might reasonably ask why they should publish data that helps somebody else build a business on their used product.

Two reasons hold. The first is that residual value at end of first life feeds back into total cost of ownership, which is increasingly how fleet and industrial buyers evaluate purchases. A battery with an established second-life route is worth more new.

The second is that the alternative is not that nothing happens. It is that packs are graded conservatively and shredded, which loses the residual value entirely and increases pressure on the recovered material supply the manufacturer itself needs to meet recycled content targets.