- What this document states
- A best estimate of usable capacity remaining, expressed as a percentage of nameplate, together with a 95% credible interval and a projection of when the pack reaches 80% of nameplate under the duty cycle observed to date.
- What it does not state
- Fitness for a particular application, safety, warranty status, or a monetary value. A certificate is an input to those judgements and not a substitute for them.
- Evidence used
- 61 charging sessions recorded over 14 months, covering 540 equivalent full cycles of pack history. No discharge capacity test was performed and the pack was not removed from the vehicle.
- Estimation
- A physics-informed degradation model: lithium inventory loss, active-material loss and resistance growth are represented explicitly, and machine learning fits the free parameters to the observed charge segments. The model cannot produce a fade trajectory the chemistry does not permit.
- Interval calibration
- Intervals are validated by coverage on held-out cells from public degradation datasets: the stated 95% interval must contain the true value on 95% of cells it has never seen. Coverage is reported with every model release.
- Reading the curve
- Solid line and solid band: the window the model has measured. Dashed line and hatched band: extrapolation. The band widens with the square root of the forecast horizon, which is why a projection ten years out is quoted as a range and not a date.
- Re-issue
- A certificate is a statement about a pack at a moment. Fresh telemetry produces a fresh certificate with a tighter interval; the previous one is superseded rather than corrected.