How we calculate your Tesla battery health

When you click Generate Passport, we call the official Tesla Fleet API endpoint /api/1/vehicles/{id}/vehicle_data with three endpoint groups:

• charge_state — usable_battery_level (%, decimal — excludes cold-locked capacity; falls back to battery_level), ideal_battery_range (km), charge_limit_soc
• vehicle_state — odometer (km)
• vehicle_config — car_type, trim_badging, exterior_color

Tesla reports the ideal_battery_range at your current state of charge. We linearly project that to a 100% charge:

range_at_100% = (ideal_battery_range / battery_level) × 100

Example: a Model 3 LR showing 354 km at 65% projects to (354 / 65) × 100 = 545 km at full charge.

We divide the projected full-charge range by the original WLTP-rated range for your exact model, year, and trim:

SoH (%) = (range_at_100% / WLTP_rated_range) × 100

On your dashboard, we display the SOC-weighted median of up to 180 days of snapshots — not a single live reading. 180 days spans Thailand's two main seasons (hot and rainy), so the median isn't skewed by temperature in any single period — while remaining short enough that the Passport reflects the car's current condition. Snapshots taken at SOC ≥ 80% are weighted 2×, SOC 50–79% at 1×, SOC 40–49% at 0.5×. The median resists outlier days caused by temperature or unusual driving. Snapshots taken within 3 days of a Tesla OTA software update are excluded to avoid artificially shifting the trend. Snapshots captured while the car is actively charging are also excluded — SOC and range are unreliable mid-charge. Snapshots taken at SOC ≥ 80% are weighted 2× because they require less extrapolation to estimate full-charge range, making them more accurate than low-SOC readings.

WLTP-rated values from Tesla Thailand: Model 3 Standard RWD 2024+ = 534 km, Model 3 Long Range RWD 2024+ = 750 km, Model 3 Performance 2024+ = 571 km, Model 3 Long Range AWD 2021–2023 = 614 km, Model 3 Standard RWD 2021–2023 = 491 km, Model Y Standard RWD = 488 km, Model Y Long Range RWD = 661 km, Model Y Long Range AWD = 629 km, Model Y L Long Range AWD = 681 km. We switched from EPA to WLTP because Tesla sells in Thailand with WLTP specifications, and Asian driving conditions are closer to the WLTP standard than EPA, which is tested in U.S. climate conditions. Values below 75% are flagged as LOW rather than discarded — high-mileage cars can legitimately reach this range. Values outside 70–104% are flagged as sensor anomalies and excluded from the median — never clamped or adjusted. The upper bound is 104% (not 100%) because near-new cars can legitimately project slightly above WLTP due to manufacturing tolerance.

Cycle count is derived from the actual energy you've put through the pack. We sum every kWh logged in your daily telemetry (home + Supercharger) and divide by usable pack capacity. If you have no telemetry yet, we show an estimated value from odometer ÷ WLTP range for this model, adjusted for Bangkok's average temperature (LFP −8%, NMC −5% vs the 23°C WLTP test condition), displayed with a ~ prefix to indicate it's an estimate.

cycles = Σ(kwh_charged_home + kwh_charged_supercharger) / pack_kWh_usable

Pack capacity (usable): Model 3 LR/Performance ≈ 78 kWh, Model Y LR ≈ 75 kWh, Model Y Standard (LFP) ≈ 57.5 kWh, Model S ≈ 100 kWh (Plaid 95), Model X ≈ 100 kWh (Plaid 95).

degradation_rate (%/yr) = (100 − SoH) / vehicle_age_years

Your SoH is benchmarked against the rolling mean of the latest health report from every Tesla in our database that matches your model, year, and 20,000-km mileage band. No external benchmark, no hardcoded number — if 18 other 2022 Model 3s with 60–80k km are in the fleet, we average those 18. When the same-segment cell has fewer than 5 cars we widen scope to same model + year, then same model, and label the comparison accordingly. The segment average is recomputed every time a new passport is generated.

fleet_avg = mean(latest_report.soh_pct for peers in same model + year + 20k-km mileage band)

When even the broadest cohort (model only) has fewer than 5 comparable cars, the certificate omits the fleet comparison entirely rather than show a fabricated number.

Each passport is written to our database with a unique public_slug and a tamper-evident URL at /passport/{slug}. Buyers can verify authenticity at any time via the public verify endpoint — /api/public/verify/{slug} — which returns the issuance timestamp and the original SoH reading.