How Certvolt verifies battery health.

Once a Tesla owner connects their account to Certvolt, our daily cron job calls the Tesla Fleet API to record:

• Battery state-of-charge — the percentage shown on the dashboard.
• Battery range — the "ideal" and "rated" range Tesla reports.
• Odometer — current mileage.
• Charge limit — what % the owner is charging to.
• Charging session details — power, energy added, charger type — when the car happens to be charging at poll time.
• Vehicle metadata — model, trim, year, factory of manufacture, software version.

All readings are timestamped and stored. Your dashboard always reflects the most recent reading, and the printable owner report captures a snapshot of that reading plus a 12-month history at the moment you generate it.

The score (0–100) is derived from the relationship between the vehicle's reported range at full charge and the EPA-published range for that exact trim and year.

For example: a 2023 Model Y Long Range has an EPA range of 330 miles. If your car reports 285 miles at 100%, that's 86% retention — a degradation of 14% over a typical ~50,000 miles. The score reflects that retention.

We pull EPA specs from fueleconomy.gov and Tesla's own published specs.

• The VIN in your report matches the title document.
• The odometer matches the vehicle's dashboard.
• The model year and trim match the manufacturer plaque.
• The report and dashboard are served from certvolt.com over your authenticated session.
• The battery range and charge state are reported directly by Tesla and recorded with timestamps.

• The capacity estimate (kWh remaining of original) — derived from displayed range, not a direct BMS readout.
• The degradation rate calculation.
• The 12-month trend chart — based on stored readings; trustworthy as long as Tesla's API didn't lie.
• The health score itself, which is our model on top of Tesla's reported data.

If Tesla's reported range is wrong, our computation reflects that error. We don't do additional cell-level diagnostics.

• Not a warranty. Certvolt does not insure or replace anything. Battery warranty is between you and Tesla.
• Not a definitive battery condition assessment. A genuine pack diagnostic at a Tesla service center reads each cell. We don't.
• Not a guarantee of future performance. Battery degradation accelerates with age, climate, and charging behavior. The score is a snapshot.
• Not a Tesla product. Certvolt is independent and not affiliated with or endorsed by Tesla, Inc.

Certvolt receives only the data needed to compute health and generate the certificate. We do not log or share precise vehicle locations beyond what's needed to fetch local weather. Owners can revoke our access at any time at tesla.com/teslaaccount → Authorized Apps. Polling stops the moment access is revoked. See our privacy policy.

Tesla owners can see their range drift on the dashboard but have no objective, research-backed way to interpret it. Certvolt sits in that gap: a free, read-only analysis that takes your car's own telemetry, compares it against EPA specs and published battery-aging research, and tells you "here's what this specific car's battery actually does, today." It's yours to keep, export, and reference — no purchase, no obligation.