Battery health becomes the new odometer In a traditional used car, buyers often focus on mileage, service records and engine condition. In a used electric car, those factors still matter, but battery capacity and charging performance have become especially important. A buyer wants to know whether the battery can deliver predictable range in real conditions, whether the vehicle has experienced unusual heat exposure and whether the remaining manufacturer warranty can transfer across markets. What the evidence actually says In January 2026, Geotab published an updated analysis of real-world battery information covering more than 22,700 electric vehicles across 21 makes and models. Its reported average annual capacity degradation was 2.3%. In the study, cars that relied heavily on high-power DC charging above 100 kW experienced rates of up to roughly 3.0% annually, versus about 1.5% for lower-power charging groups. Vehicles in hot climates degraded approximately 0.4 percentage points faster each year than those in milder climates. These are group-level findings; they do not predict the remaining capacity of an individual car. Why a single percentage is not enough Battery state of health (SOH) can be calculated differently by diagnostic tools and manufacturers. A displayed percentage may depend on the vehicle's battery management system, calibration, firmware and testing conditions. An independent used-EV inspection should compare available onboard diagnostics, fault codes, charge and discharge behavior, cell-balance indicators where available and a measured range or energy-consumption test. A battery should never be declared healthy based on dashboard-estimated range alone. A practical exporter inspection protocol Before accepting a vehicle, confirm the exact battery configuration, inspect the underbody and battery enclosure for damage, request charging records when available, verify that AC and DC charging function correctly, scan for persistent errors, and check cooling-system operation. Photograph the dashboard mileage, battery information and diagnostic results. Where an inspection uses third-party tools, record the tool name, software version, date and limitations. Do not describe a battery-health value as certified unless an appropriately qualified provider has validated it. Turning trust into resale value A transparent condition file can shorten the negotiation cycle and make comparisons across suppliers easier. Buyers should receive a plain-English battery summary, vehicle history, clear photos of relevant areas, charging compatibility information and warranty exclusions. As used EVs travel farther from their original sales markets, measurable battery condition can become a competitive distinction between a professionally sourced vehicle and an attractive but poorly documented listing.