Tesla battery packs last longer than you’d think — a whole lot longer

Concerns about electric car batteries wearing out may be unfounded. Data collected by a Tesla owners’ group show it’s unlikely the Model S battery pack will degrade to less than 90 percent over 200,000 miles or even further, according to Electrek.

Tesla owners who participate in a Dutch-Belgium Tesla forum are tracking 286 Tesla Model S owners around the world. The group updates the information in an open Google Docs spreadsheet.

Apparently, from the data, most Tesla S battery packs maintain about 95 percent capacity after the initial 50,000 miles. However, after that mileage, battery pack degradation is very slow, so slow it appears an additional 5 percent degradation might take at least another 150,000 miles. The group has extensive data and charts, including trend lines that show the aggregate data result and the outliers — those cars with numbers far from average performance.

Another factor tracked in the collected data, which is an ongoing project, is the effect, if any, on the use of Tesla Supercharging stations on battery pack degradation. According to one of the charts from the forum, “When looking at the general trend, supercharging more frequently seems to be better for the battery than supercharging less frequently. One possible explanation is that, during supercharging the battery is subject to heat for a shorter time, thus reducing parasitic reactions.”

During Tesla’s annual stockholders’ meeting this year, CEO Elon Musk mentioned a battery pack they were testing that at the time had more than 500,000 simulated miles and was still holding more than 80 percent of its original capacity.

According to Electrek, Tesla has established a drive unit lifetime goal of at least 1 million miles. If the battery packs can hang in that long, which the Dutch-Belgium forum’s data suggests might not be beyond the realm of possibility, there may be a lot of million-plus mile Teslas in the future.

Assuming you currently drive 10,000 to 20,000 miles a year, it appears that, if the Tesla owners’ group data is accurate and if it represents an indication of electric car battery packs in general — two significant ifs — it would take you 50 to 100 years to hit the million-mile mark so you could then check the remaining battery level. So maybe we can just be concerned about expanding the charging infrastructure rather than how long the batteries will last.

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