Battery health matters more than mileage when buying a used electric car. Ask the seller for a battery health report, or run one yourself through the car's app if you have access before purchase. Check for consistent charging history rather than a string of fast-charge sessions, which accelerate degradation. A healthy battery on a 3-4 year old EV should retain at least 90% of its original capacity. Also inspect the charging port for wear, and ask about any software update history — some issues reported by early owners were resolved entirely through updates.