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EV Evidence

Used EV evidence · UK

Battery capacity and resistance are different metrics

Capacity and resistance are separate battery-health metrics and must not be treated as interchangeable. The E2 Lam study tracks relative capacity and relative resistance as distinct measurements during diagnostic cycles. For a used EV, require the report to name the method, reference and conditions for each result.

Joule: A decade of insights: Delving into calendar aging trends and implications

Reviewed

Key facts and evidence

For a UK used-EV assessment, as of 13 August 2026, capacity and resistance must be read as separate measurements. The E2 Lam study reports each relative to its own initial value, and official OZEV evidence guidance distinguishes capacity and impedance approaches. Neither metric can be silently converted into the other or into a complete battery verdict.

Joule: A decade of insights: Delving into calendar aging trends and implications

Capacity and resistance results answer different battery questions and should remain separate in a vehicle-specific health report.

Capacity evidence

Capacity in the Lam evidence is Q(t) relative to Q(0), measured during periodic diagnostic cycles. The definition is tied to that laboratory protocol and is not a dashboard-range measure.

Resistance evidence

Resistance in the same study is R(t) relative to R(0). It remains a separate trajectory, so a resistance change is not a substitute capacity result and a capacity result does not disclose resistance behaviour.

Sources and review dates

Lam and colleagues published the licensed study online on 18 December 2024; E2 checked it on 13 August 2026. OZEV's official evidence guidance was accessed and verified by E3 on 12 August 2026.

Limit and next step

The Lam study covers laboratory calendar ageing and excludes vehicle range, field replacement, cycling duty and pack controls. For an individual purchase, follow E3 row e3-s11-008 and obtain a vehicle-specific report whose issuer explains both metrics.

What to do next

Neither a capacity result nor a resistance result on this page determines whether a vehicle should be driven.

Immediate action: Separate every capacity result from every resistance or impedance result.

  • Do not combine results when their references, methods, temperatures or test conditions differ or are missing.

Checks that stay with this vehicle

  1. Check that the written report labels capacity and resistance or impedance separately and states the reference, method and conditions for each.

    Each reported value has a traceable meaning without being converted into the other metric.

    Treat the evidence as incomplete if one percentage is presented as a combined battery-health answer without definitions.

Professional hand-off

  • Ask the report issuer or an independent EV-competent battery specialist to explain any undefined or blended metric.

Questions this record can answer

What does the sourced evidence say about capacity evidence?

Capacity in the Lam evidence is Q(t) relative to Q(0), measured during periodic diagnostic cycles. The definition is tied to that laboratory protocol and is not a dashboard-range measure.

What does the sourced evidence say about resistance evidence?

Resistance in the same study is R(t) relative to R(0). It remains a separate trajectory, so a resistance change is not a substitute capacity result and a capacity result does not disclose resistance behaviour.

What does the sourced evidence say about sources and review dates?

Lam and colleagues published the licensed study online on 18 December 2024; E2 checked it on 13 August 2026. OZEV's official evidence guidance was accessed and verified by E3 on 12 August 2026.

Sources