Photo Credit: iStockA warranty-covered battery swap on a Tesla with 100,000 miles is drawing attention to a common long-term EV concern: What happens if the battery pack fails after years on the road?In this case, the answer was expensive in theory but free for the driver.Here's what to knowIn a recent video, the creator behind Driving Forward Builds and Serenity EV explained that their 2021 Tesla Model Y Performance needed a new high-voltage battery after the car displayed several warning messages, including a "Replace Battery Pack" alert.Battery packs are among the most expensive parts in any electric car, so the warning could have cost the creator a significant amount of money to replace. Luckily for this driver, it was fully covered under Tesla's warranty.AdvertisementAdvertisementThe video also included a before-and-after comparison. "Before the failure, my Model Y was showing roughly 240-250 miles at 100% depending on conditions," the creator wrote in the video's description. "After the replacement, it showed 300-303 miles, essentially right around the original EPA range for the car."More backgroundBattery problems can happen even in a relatively modern EV, and warranty protection can cover a major component failure.EV ownership often comes with everyday savings. Drivers avoid gas station fill-ups, skip oil changes, and often spend less on routine maintenance because electric drivetrains have fewer moving parts than gas-powered vehicles. A covered battery replacement helps preserve those savings by eliminating what could otherwise be a major surprise expense.AdvertisementAdvertisementThe creator said Tesla completed the battery replacement in about a week. After the Model Y returned, the video showed the pack from underneath the vehicle and included the creator's observations about Tesla's installation.What can be done?Warning alerts and service paperwork can be central when a vehicle develops a battery management system fault, especially if it displays language as direct as "Replace Battery Pack."Remaining battery and powertrain warranty coverage can matter just as much as mileage, tire wear, or cosmetic condition since coverage on a major component could save thousands of dollars.Drivers can compare a car's displayed full-charge range with its original rated range, though weather, wheels, driving style, and software can all affect the number. A range figure alone isn't a diagnosis, but it can still serve as a useful data point.AdvertisementAdvertisementFor many households, electrification still makes financial sense — especially when a vehicle's biggest components are covered and the owner can continue benefiting from lower fueling and maintenance costs.Get TCD's free newsletters for easy tips, smart advice, and a chance to earn $5,000 toward home upgrades. To see more stories like this one, change your Google preferences here.