Tesla Model Y Battery Degrades to 88% After 21,000 km

A YouTube blogger recently conducted Tesla’s official built-in battery health test on their 2025 Tesla Model Y Long Range RWD, which they had owned for 18 months and driven 13,162 miles (approximately 21,182 km). The test revealed a battery health of 88%. The vehicle was not subjected to intensive usage and was primarily used for personal purposes. Previously, the blogger reported a battery health of 95% at around 6,000 miles (approximately 9,656 km) and a drop to 90% by approximately 11,000 miles (about 17,703 km). All tests were performed following Tesla’s official procedure: fully depleting the battery to near empty, then plugging into a Level 2 AC charger overnight to charge to 100%, allowing assessment of each individual cell’s condition. The most recent test took 12 hours; at full charge, the vehicle displayed a range of 302 miles (approximately 486 km)—36 miles (about 57.9 km) less than the new vehicle’s rated range. Approximately 43% of the vehicle’s charging came from a home Level 2 AC charger, while 57% used DC fast charging, including Tesla Superchargers (up to 250 kW) and 50 kW DC fast chargers. The car has been consistently parked outdoors, with Sentry Mode and Cabin Overheat Protection permanently enabled. The latter feature activates the air conditioning to prevent cabin temperatures from exceeding 105°F (approximately 40°C), resulting in relatively high energy consumption even when parked. Despite these usage conditions, experts consider the current level of degradation—given the vehicle’s age and mileage—to be on the higher side. The blogger estimates that if degradation continues at this pace, battery health will fall to 82% by the end of their 18-month lease term. However, professionals from battery testing organizations note that EV battery degradation typically occurs more rapidly in the early stages and tends to slow down after dropping to around 90%. They also emphasize that battery health is influenced by multiple factors, with driving mileage being just one of them.