Evidence trace record: following one passport claim back to its supporting evidence

An evidence trace follows one claim in a battery passport back to the evidence that supports it. A claim in this sense is a stated value, a stated fact or a stated status, together with its scope, date and source. The trace answers a narrow question: what document, test result, measurement record or supplier statement stands behind this particular entry. A passport that cannot answer that question for a material claim asks a reader to trust the display rather than the record.

Trust in a record comes from traceability, not from presentation. The method below works claim by claim, because a whole record traced at once hides weak links behind strong ones.

What is a claim in a passport record?

A claim is any entry that asserts something about the battery. Rated capacity is a claim. A chemistry description is a claim. A carbon footprint figure is a claim. A state of health value is a claim. A status such as repurposed is a claim. Even an identity entry is a claim, because it asserts that the identifier belongs to this battery and that the model identifier matches the technical documentation. Claims differ in strength. A claim backed by a dated test report with stated conditions is stronger than a claim backed by a supplier summary with no conditions. A claim with no source at all is an assertion, not evidence. The first step in a trace is to list the claims in the entry being checked, in the order they appear, and to mark each one as sourced, partly sourced or unsourced before any judgement about accuracy is made.

How is a trace built for one claim?

A trace is built in four steps. First, the claim is quoted exactly, with its value, unit, scope and date. Second, the evidence cited in or linked from the record is identified by title, date and holder. Third, the evidence is inspected for match: same battery model, same manufacturing plant where relevant, same test conditions, same date range. Fourth, the result is recorded as matched, partly matched or unmatched, with the reason stated. A carbon figure traced to a declaration for a different manufacturing plant is partly matched at best. A capacity figure traced to a test report for a different model is unmatched. A state of health figure traced to a measurement log with no date is partly matched, because the value may be correct and the currency is unknown. The trace record is itself a record, and it should be retained with the date of the trace and the identity of the evidence inspected.

Which evidence types appear most often?

Technical documentation under Annex VIII supports identity, design and conformity claims. Test reports support performance, durability and safety claims, and sit in the authority tier under Annex XIII point 3. Supplier statements and chain of custody records support composition, origin and recycled content claims. Due diligence reports support responsible sourcing claims. Measurement logs from a battery management system support state of health claims. Each evidence type has a different weakness. Technical documentation can be out of date after a model revision. Test reports can cover a sample rather than the unit. Supplier statements can describe a material family rather than the batch used. Measurement logs can lack calibration or reference conditions. A trace notes the weakness alongside the match, so that a later reader does not mistake a matched citation for proof that the underlying evidence was sufficient.

What does a worked trace look like?

How are gaps in a trace recorded?

A gap is recorded as a gap, with the claim, the evidence sought and the outcome of the search. A gap is not filled by an assumption, a neighbouring value or a statement that evidence is held elsewhere without a reference that allows retrieval. Where evidence is held by another actor, the trace records the holder, the reference and the route by which the evidence can be requested, without asserting that the evidence exists. Where evidence was inspected but did not match, the trace records the mismatch in neutral terms: different model, different plant, different date range, or conditions not stated. Neutral recording matters because a trace is often read by a party with an interest in the outcome, and loaded language undermines the trace itself. The trace should also record claims that were not traced, so that a partial trace is not mistaken for a complete one.

What limits apply to a trace?

A trace checks that a claim is supported by the evidence cited. It does not prove that the evidence itself is correct, that a test was performed properly, or that a supplier statement was truthful. Those questions require inspection of the evidence, testing, audit or verification by a notified body where the Regulation provides for it. A trace also does not convert a model level claim into a unit level fact, or a public tier summary into authorised detail. The trace stays inside the tier and layer of the claim being traced. This guide gives general educational information only and does not give legal advice for a particular battery, claim or transaction.