What your certificate states — method version cert-2.5.0

This page explains certificates of method version cert-2.5.0. The version is stated on every certificate. It is tied to the signed wording: a certificate issued today is to be read against this explanation in five years' time, not against a later edition. The calculation procedure is set out in our methodology, the revision history in the change log.

New compared with cert-2.3.0: the document carries a range on a WLTP basis in kilometres, where a vehicle-specific WLTP figure for the as-new state is available. The earlier range estimate has gone: it divided the measured energy by one consumption value used for every vehicle, which looked like a measurement and was a division. The headline figure, the band and the issuing gate are unchanged.

Each figure is explained in three sections: what is stated, how the value is derived, and which claim it does not make. The third section is the material one.

Energy retention (SoCE-like)

What is stated. The estimated usable energy of the battery at the reference date, relative to a documented as-new reference energy for the same model variant. Alongside it stands an uncertainty band ("± 2.4%"), which forms an equally important part of the figure.

How the value is derived. From the progression of state of charge and energy across several measurement runs, the slope of stored energy over state of charge is determined, rather than a single quotient. The reserve below the displayed discharge limit — around 3 kWh on the test vehicle — therefore cancels out instead of entering the figure as usable capacity.

Which claim it does not make. The figure is an estimate with a stated uncertainty, not a laboratory measurement. The term "SoCE-like" indicates that the quantity is modelled on the State of Certified Energy under UN GTR 22 but is not determined by that procedure: no test cycle was driven and no type approval granted. Certificates from different providers are comparable only insofar as they use the same reference quantity; the one used here is stated immediately alongside.

Relation to the term "SoH". In everyday use, a figure like this is called State of Health. This document does not call it that, because SoH presupposes the as-new state of this particular vehicle, and that vehicle's initial capacity was never measured. The figure answers the same question (how much energy the battery still takes in today compared with new), but it discloses which reference quantity it is measured against.

Usable energy

What is stated. The numerator of the percentage, in kWh: the amount of energy available between a full charge and the discharge limit indicated by the vehicle.

How the value is derived. From the slope described above, extrapolated across the full charging range.

Which claim it does not make. The figure does not denote the gross cell capacity, nor the manufacturer's data sheet value. Between gross and usable capacity lie reserves that the vehicle keeps in hand by design.

As-new reference energy

What is stated. The reference quantity of the quotient: the usable energy of this model variant when new. A quality note may be added:

• Variant resolved — the specific variant is identified; the reference quantity is a documented manufacturer figure.
• Variant band · midpoint of two documented packs — two different battery packs are documented under the same model designation and cannot be distinguished from the available characteristics. The reference quantity is their midpoint; the spread is accounted for in the uncertainty band. No claim is made as to which variant is fitted.
• Line-level figure · greater uncertainty — present only in earlier certificates; since August 2026, no certificate is issued without a resolved variant.

How the value is derived. From a versioned table of reference quantities, not from the vehicle's model designation. The same designation covers technically different vehicles across model years.

Which claim it does not make. The reference quantity is not a measurement of the particular vehicle when new. Manufacturing spread between identical packs is accounted for in the uncertainty band rather than in the figure. Altering the reference quantity changes the percentage without any change in the condition of the vehicle; the table is therefore versioned and held fixed for the duration of the ongoing validation study.

Charging sessions or individual data points

What is stated. The number of observations entering the estimate. The label identifies the unit counted:

• Charging sessions — each entry corresponds to one complete charging session admissible for the analysis, each underpinned by a large number of individual readings.
• Individual data points — each entry corresponds to a single reading within a measurement run.

How the value is derived. Only observations that passed the admissibility check are counted; runs that are too short, too widely scattered, or mixed across data sources are excluded beforehand.

Which claim it does not make. The figure does not state the total number of charging sessions of the vehicle, nor does it indicate a thin evidence base. Nine charging sessions evaluated constitute nine complete measurement situations, not nine individual values. Whether the evidence supports the estimate is read from the uncertainty band, not from this count.

Trend per 10,000 km and measured decline

What is stated. The change in usable energy across the distance and time observed to date, given in kWh per 10,000 km and in kWh per year.

How the values are derived. From a regression across the measurement runs, kept separate from measurement scatter. An axis is stated only where it could actually be estimated: below a span of 5,000 km or 90 days, no slope is determined. Where the certificate instead notes an insufficient span, that is the accurate statement — and is not to be equated with a trend of zero.

Which claims they do not make. The values are not a forecast. Battery ageing is not linear; the first percentage points decline more rapidly, after which the curve flattens. Extrapolating the observed decline linearly systematically understates remaining service life.

Range on a WLTP basis

What is stated. A range equivalent, strictly speaking: the WLTP range of this vehicle when new, scaled by the measured ratio of today's usable energy to the as-new figure — in kilometres, with the headline figure's band in kilometres beside it. Below it stands the as-new figure itself and where it comes from. The certificate shows the figure only where a vehicle-specific as-new value exists; otherwise it is absent altogether.

How the value is derived. From two numbers: the official WLTP figure for this vehicle when new, and the retention ratio stated above. Two sources for the as-new figure are admissible. Either this vehicle's certificate of conformity; or the official value for this exact specification from open EU vehicle registers, resolved through battery pack, model year, version class and factory wheel. WLTP consumption does not enter the calculation: it sits inside the as-new figure and cancels against itself.

Why not a value for the variant. Under one and the same variant code, the registers carry up to four different official ranges, as much as 19% apart — more than the signal the measurement itself provides. What decides is the vehicle's road-load set, which no vehicle interface supplies. Where the specification cannot be determined unambiguously, the figure is omitted; an average would describe no vehicle at all.

Which claim it does not make. The number is calculated and not a WLTP measurement: no test cycle was driven. Neither is it a forecast for everyday driving — WLTP is optimistic against real-world use, markedly so in the cold, at speed or when towing. Its purpose is comparison with the figure stated on every new car. It is no more precise than the percentage: it is the same measurement in a different unit. It assumes that consumption per kilometre does not change with age, and that assumption cannot be tested with our field data.

Data provenance and quality tier (Q1–Q4)

What is stated. The source of the measured energy and the robustness of that channel. Without this information a percentage cannot be interpreted.

How the value is derived. From the channel that supplied the stated figure. Where the underlying history contains several sources, all are named.

Which claim it does not make. The tier ranks data quality, not the independence of the measurement; a higher tier therefore does not denote the more independent figure. Q1 offers the highest data quality — high sampling rate, energy directly in kWh, no conversion constant — yet remains a quantity the vehicle estimates itself. Q2 is the only tier that captures a quantity the vehicle does not estimate: the energy actually delivered. Both characteristics are therefore stated separately, and a Q2 certificate carries the note "measured independently of the vehicle's own estimate".

Q4 is the weakest tier: deriving the figure from the range display via a constant can yield values above 100%. It serves solely as a plausibility check and not as the primary estimator.

What limits the accuracy

What is stated. The influence currently dominating the uncertainty band. It is the only figure on the document from which the owner can derive a concrete measure — such as making fuller use of the charging range, awaiting further measurement runs, or restoring an interrupted data feed.

How the value is derived. The terms of the uncertainty budget add up in quadrature; the largest is named. Where the second largest lies within 10%, no dominant term is stated and the certificate notes instead that several influences contribute to a comparable extent.

Which claim it does not make. The note does not denote a fault in the vehicle. A wide band quantifies the remaining measurement uncertainty, not a poor battery condition.

Battery status date, issue date and odometer

What is stated. The time of the last measurement together with the corresponding odometer reading — not the time at which the page is opened. Where that date lies several months back, the certificate flags this actively.

Which claims they do not make. A certificate remains bound to its reference date. The stated odometer reading should be compared with the vehicle's own: if several thousand kilometres lie between them, the document describes an earlier condition.

VIN checksum and signature

What is stated. The binding of the document to one particular vehicle and to an unaltered wording.

How the entries are derived. The full vehicle identification number is not contained in the certificate; only its SHA-256 digest is. Anyone who knows the full number can check on the certificate page whether it matches that digest. The wording itself is signed with Ed25519; verification is performed automatically in the browser when the page opens, using an embedded public key and transmitting no data.

Which claims they do not make. A valid signature establishes that the document originates from us unaltered — not that the battery is in good condition. The percentage remains an estimate even where the signature is valid.