One Pack's Visible Carrying Roles Narrowed Without a Mirroring Capacity Decline

Executive Summary

• What this dataset can observe. One 36-cell 3P12S laboratory pack was recorded at 2 Hz during WLTP and capacity-check protocols. The observable object is how voltage-response carrying roles are distributed among cells across the pack's own history.
• What held after audit. The visible carrying field contracted toward roughly two reachable bearers under WLTP, while P1S6 became the persistent late dominant bearer. The matched capacity-check view showed the same identity and a still narrower late breadth.
• What did not follow. Capacity checks showed no decline mirroring that organisational contraction. This is a contrast between two measured layers, not a claim that capacity is irrelevant.
• What was rejected. The field looked wider near rest, but the widening disappeared under load. It therefore failed the persistence-under-load gate and is not reported as recovery.
• Boundary. These traces do not establish state of health, remaining life, failure, safety, fault, warranty outcome, or material mechanism.

Dataset & Attribution

Original dataset. Joaquín de la Vega Hernández, Juan Antonio Ortega Redondo and Jordi-Roger Riba Ruiz, Lithium-ion battery pack cycling dataset with CC-CV charging and WLTP/constant discharge profiles, CORA.Repositori de Dades de Recerca, V3, [DOI 10.34810/data2395](https://doi.org/10.34810/data2395). The dataset is public under CC BY 4.0.

Analysed snapshot

LFR analysed a read-only local mirror copied on 2 July 2026. Its 412 source files are consistent with the released V3 record at filename and byte-size level. Dataverse exposes the WLTP reference as an ingested .tab; the original CSV retained in the LFR mirror matches the remote original-format file exactly by size and MD5. This is a snapshot identity statement, not a claim about sensor calibration or physical representativeness.

Associated publication

The original authors describe the test bench, 3P12S pack, WLTP construction, sensing channels and data record in de la Vega Hernández, J., Ortega-Redondo, J.A. & Riba, J.-R., Lithium-Ion Battery Pack Cycling Dataset with CC-CV Charging and WLTP/Constant Discharge Profiles, Scientific Data 12, 1942 (2025), [DOI 10.1038/s41597-025-06229-5](https://doi.org/10.1038/s41597-025-06229-5). The paper is cited here for dataset and measurement context. It does not supply or validate the LFR bearer-contraction, role-lock, null-control or overturn results on this page.

The pack's visible carrying field narrowed

Observed

For each cycle, the analysis asks how many cells were effectively available to occupy the most constrained voltage-response role. That reachable breadth contracted from an early WLTP estimate of 6.73 to 2.19 over 295 cycles. The early absolute estimate is soft because several cells were nearly indistinguishable; the robust statement is the contraction toward two, not that the pack began with exactly 6.73 bearers. The capacity-check face independently moved from 2.65 to 1.03.

Interpretation

A time-shuffle control did not reproduce the ordered contraction (observed Spearman rho -0.650 versus a null centred at 0.000 with SD 0.060; two-sided permutation p = 0 in 1,000 draws). This supports a biography-level change in the recorded role distribution. It does not identify an electrochemical cause.

The late role stayed with one bearer

Observed

P1S6 occupied the top bearer rank in 76.8% of late WLTP cycles and was also the dominant bearer on the matched capacity-check face. Late cross-cycle cell-rank stability was 0.970 in the WLTP recomputation and 0.952 in the capacity-check view. The identity-shuffle controls were centred at zero.

Interpretation

This supports a persistent visible bearer identity under matched protocol views. It does not make P1S6 a failed cell, a dangerous cell, or a material diagnosis. It says only that the recorded carrying role stopped rotating freely and became concentrated on the same named cell.

Capacity did not mirror the organisational contraction

Observed

Across 99 valid capacity checks, the audited result freezes only an absence statement: capacity showed no decline that mirrored the carrying-field contraction. Raw episode ampere-hour magnitudes remain descriptive because protocol depth and model-constructed SOC affect their interpretation.

Interpretation

The comparison establishes that the capacity scalar and the role-distribution lens answered different questions in this pack. It does not show that capacity is unimportant, nor does it convert role concentration into a health or failure claim.

Rest made the field look wider, but did not reopen it under load

Observed

Late in the record, effective breadth increased from 1.03 under load to 2.10 at rest. Read alone, the rest value could look like recovery. The forcing ladder is the critical check: the apparent reopening grows only as current approaches zero.

Interpretation

Because the wider field did not persist when load returned, the audit classified it as a relaxation impostor and froze it as a null. The allowed sentence is not 'the pack recovered at rest'; it is 'rest-only apparent reopening failed the persistence-under-load gate.'

What made us doubt the reading

• Protocol boundary: a fitted onset near cycle 127 lies within two cycles of a protocol-depth change at cycle 125. The structural divergence survived fixed-SOC and within-branch checks, but its sharp timing is not claimed as physics.
• Early near-degeneracy: the early WLTP breadth of 6.73 is not treated as an exact starting population.
• Weak control: a baseline-swap correlation looked strong but was judged low-power and does not carry the identity claim.
• Missing channels: dead sensors P3S11 and P1S5 were excluded. No teardown, reference electrode, imaging, or synchronous mechanism channel is available.

What the result resisted

The contraction survived time shuffling. The named bearer survived cell-identity shuffling and reappeared on the matched capacity-check face. In a separate counterfactual-removal test, removing P1S6 restored reachable breadth by 1.1834, while the random-cell pool averaged -0.0075 and no non-bearer exceeded 0.0420. These controls make the late concentration harder to explain as arbitrary ordering, one protocol face, or interchangeable cell labels.

What remains unknown

The trace does not reveal why the role concentrated, whether an internal material mechanism caused it, whether the same pattern would recur in another pack, or whether it changes safety, life, warranty, or residual value. A former thermal-coupling reading was overturned: bearer temperature and voltage stress co-drifted over life, but detrending removed the apparent coupling. No bearer-specific thermal-coupling number is citable.

Recommended next step

Use this page as the reporting contract for the next mature substrate: begin with the observable object, show only audited relations, place the carrying null beside each headline, and give overturned or unsupported interpretations equal visual status. For QTZL itself, any successor page should reconcile the later windowed contract before adding fresh candidate language.

Further Questions

• Does the same role concentration recur in another independently observed pack under a comparable protocol?
• Which additional physical channel would distinguish competing mechanism explanations without borrowing meaning from voltage alone?
• Under what forcing changes does the named bearer remain fixed, and where does the role genuinely migrate?

Caveats and Assumptions

This is one laboratory pack, not a population estimate. Cells are treated as organs of that individual; results are not pooled into a universal battery rule. Native zero and units are preserved, smoothing is not used upstream of cadence or lag metrics, and dead sensors are excluded. This pilot compiles the stable audited QTZL sentence sheet; it does not promote later windowed candidates that still require successor reconciliation.

Sources & Reproducibility

Original evidence. The public [CORA.RDR dataset](https://doi.org/10.34810/data2395) is the source of the recorded pack traces. The associated [Scientific Data paper](https://doi.org/10.1038/s41597-025-06229-5) documents the authors' experimental and data-collection context.

LFR derivation. The response-organisation metrics, matched-face comparisons, destructive nulls, verdicts and wording boundaries are LFR analyses. Their machine-readable source chain is: frozen normalisation and channel roles → reproduction manifest → headline and continuation null verdicts → thermal re-adjudication → audited sentence sheet → the canonical artifact identified by this substrate publication package and its source receipt.

Authorship boundary. The dataset authors did not produce or endorse the LFR response-organisation readings. Citing their paper identifies the measured object and acquisition context; it does not transfer authority from the paper to our derived claims.

Claim Boundary

Raw values preserved; zero-preserving within-branch residuals in native units; no smoothing upstream of cadence/lag metrics; dead sensors excluded; observation layer only. — Observation/measurement layer only. Not SOH, not RUL, not safety, not fault, not remaining-life, not warranty/underwriting/investment advice. It shows response-organisation continuity patterns visible in the named channels. Material-mechanism interpretation requires independent physical evidence (EIS / teardown / reference electrode / imaging).