In the "2020 Impact Report." Tesla reiterates high battery capacity retention (low degradation) in its electric cars.
According to the company's data, the average vehicle battery in Tesla should still have about 90% of its original capacity after 200,000 miles (322,000 km) of usage.
"Capacity retention of Tesla vehicle batteries averages ~90% after 200,000 miles of usage"
That's a very good result of just 10% battery capacity (and range) degradation: 1% per 20,000 miles (32,200 km).
Assuming 250 miles per full cycle (just for illustrative purposes), it's also about 800 cycles with a degradation rate of 1% per 80 cycles (or a higher number of partial cycles).
That's a lot, especially since typically a car is scrapped after about 200,000 miles in the U.S. In Europe, it's 150,000 miles (241,000 km). Tesla's approach is to design the pack in such a way so they could outlast the car.
In other words, batteries should not be a problem and besides the rare faulty battery, the normal user probably will never have to worry about replacing the pack.
Model S/X data
Those two cars are equipped with cylindrical battery cells (1865 format, NCA lithium-ion chemistry), supplied by Panasonic from Japan.
As we can see, vehicles with mileage between 150,000-200,000 miles (241,000-322,000 km), on average, still have more than 85% of initial battery capacity (the battery degradation is below 15%). Actually we can see about about 88% at 200,000 miles (red line).
- the initial battery capacity fade is higher in the beginning and then stabilizes at a slower rate
- we estimate (from the chart) that the first 5% of battery capacity is gone (on average) after about 25,000 miles (40,000 km)
- another 5% (total of 10%) is gone (on average) around 125,000-150,000 miles (200,000-241,000 km), but it's difficult to estimate because the curve is really flat
- after 200,000 miles (322,000 km), on average, the capacity degradation is below 15% (the car still has more than 85% of the capacity and corresponding range)
- the lowest capacity within the standard deviation (see wiki) is above 80% after the 200,000 miles (322,000 km), but there might be cases worse than that (the population of those cases might be 10-20% we guess)
- there is a higher variation in the high mileage results (150,000-200,000 miles) as there are simply fewer cases and some might be very specific.
- keep in mind that time, temperatures and other factors (like how long the battery stayed at a high state-of-charge levels) also influence the battery degradation.
For obvious reasons, the chart does not include the data for the latest refreshed Model S/Model X. The new versions of Model S/Model X (from 2021) are also equipped with 1865 battery cells from Panasonic (Japan), but both the packs and modules have been fully redesigned. Their battery capacity retention might be different.
We can't say anything about the battery capacity retention in Model 3/Model Y, equipped with 2170-type cylindrical cells (various suppliers - Panasonic, LG Chem's LG Energy Solution) as well as prismatic LFP cells (CATL in China). We would love to see a similar chart specifically for the Model 3/Model Y, especially since those two cars already saw more than a million units sold.