Factory Calibration & Pack NVM

Use a schema first layout with six blocks: identity, model, lifetime, signatures, traceability, and logs, stored across versioned pages P0 to P3. Keep immutable traceability and key identifiers in OTP, and put updateable models, counters, and logs in EEPROM or Flash. Cross brand swaps require mapping.csv plus downgrade rules and a migration snapshot with rollback safety.

Place part number, serial, manufacturer, date code, key identifier, key injection time, initial schema version, and trace lot or station in OTP for immutable traceability. Store updateable items in EEPROM or Flash: OCV LUT and model parameters, lifetime counters, trigger logs, calibration version, and the migration flag. This clean split keeps audit trails while allowing safe in field updates.

Persist burn in impedance and reference capacity in fixed point formats with documented ranges and units. Guard writes with page version headers and CRC, and validate ranges before commit. Older firmware reads previous versions; newer firmware migrates by downgrade policy or cloud infer when precision changes. Avoid schema free blobs so compatibility and auditing remain predictable across vendors.

Count Cycle_Total when cumulative depth of discharge meets or exceeds eighty percent, possibly across sessions. Track Cycle_EQ_1C as the sum of absolute charge throughput divided by Capacity_Ah_ref. Increment FastCharge_Count only when current is at least zero point eight C for longer than five minutes with a ten minute debounce. Aggregate environmental hours by temperature zones for comparable analytics.

Sign a digest produced by HMAC SHA256 over serial number, Coulomb_Signed_Base, Energy_Wh_Acc, Last_Cal_TS, and a monotonic counter. Keep KEY_ID and injection time in OTP, and run signing in a line HSM or trusted execution environment. At runtime the charger or gateway verifies the signature and reports status; no key material is readable in the field.

Require mapping.csv that fully covers A to B fields and declares default, locked, or cloud infer behavior. Set MIGRATION_FLAG and store a read only schema snapshot. Update the cloud telemetry mapper before allowing line writes. Keep a mirror of original pages for rollback on CRC or signature failure. Acceptance reports must summarize mapping coverage and any downgraded fields.

Append Trigger entries with type, timestamp, battery voltage, temperature, and reason into a fixed size ring buffer with batched flush. After each commit update Last_Trigger and the appropriate Trigger_Counts index. Protect pages with CRC and roll back on interrupted writes. Enumerations should include Wake, Ship, over temperature, under voltage, and over current for consistent fleet level analysis.

Yes, you can gate calibration using the main battery NTC as a temperature window, but record the source and expected accuracy in the model. Keep JEITA zoning separate from calibration windows to avoid policy confusion. If the NTC accuracy or placement is uncertain, prefer conservative limits and mark fields for cloud infer rather than overwriting trusted baselines.

Run first charge learning only after assembly checks pass and required model fields exist. On completion write Last_Cal_TS and lock CAL_VER. If mandatory data are missing, reject the unit or keep models read only until acceptance succeeds. Attach a short trigger exercise and verify summaries so the pack leaves the line with auditable, reproducible calibration signals.

Treat smaller target grids as backward compatible and read directly. For larger or different grids, refuse writes or migrate by sampling and regression into the standard seventeen by three layout with range and monotonic checks. Record OCV_LUT version, clamp units in millivolts, and track precision loss so analytics can distinguish true aging effects from representation changes.

Add four hard gates to the BOM: NVM schema version required; cross brand substitutions must submit field mapping and a downgrade policy; signed safety metering is mandatory and devices without telemetry are not accepted; update the cloud telemetry mapper before any vendor switch; and do not substitute parts lacking NTC or JEITA compliant temperature zoning for charging policy decisions.

Execute a repeatable flow: connect the device, perform full readback, validate page CRC, optionally compute a global hash, verify signatures if enabled, and check model dimensions and ranges. Write and read three triggers to exercise the ring buffer. Export acceptance-report.json with page states and summaries, archive by serial number, and quarantine any failing units.