The number everyone repeats is a projection
Geotab, a company that tracks commercial vehicle fleets, measured energy moving in and out of the batteries in 22,700 electric vehicles covering 21 models. The measurement produced an average annual battery degradation rate of 2.3%, the yearly loss in what the industry calls state of health, the percentage of original capacity a battery still holds. Geotab then projected that rate forward and stated that an average battery would hold 81.6% of its original capacity after 8 years. A report published by Geotab calls that number a projection, not a measurement, because none of the vehicles in the study have actually reached 8 years old. The same projection splits by charging habit. Cars that make light use of direct current fast charging, the high speed chargers found at highway stops, are projected to hold 88% of capacity after 8 years. Cars that make heavy use of that fast charging are projected to hold only 76.0%.
All 3 figures are projections run forward from measured annual degradation rates, not direct readings on cars that have reached 8 years. Fleet average uses a 2.3% annual rate, light fast charging use a 1.5% annual rate, and heavy fast charging use a 3.0% annual rate.
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| Light fast charging use | 88 |
| Fleet average | 81.6 |
| Heavy fast charging use | 76.0 |
What actually gets measured on cars that have gotten old
Recurrent, a company that tracks a separate community of more than 30,000 connected electric vehicles, reports that direct measurements at 8 years are still scarce, because roughly 75% of the electric vehicles on the road were sold in or after 2023. Where Recurrent could measure rather than project, the results run ahead of the Geotab projection. Among the 100 highest mileage vehicles in that community, each with 175,000 miles or more and 55% from model year 2015 or older, measured average range retention came to 86 to 87%. That sample skews heavily toward 1 brand, 87% of the 100 vehicles are Tesla, so it is a real measurement rather than a model, but not a representative slice of every electric car on the road.
The outcome buyers actually fear stays rare
Across the entire Recurrent dataset, including cars more than 10 years old, under 4% of vehicles have needed a battery replacement outside a major recall. Broken down by vehicle generation, the replacement rate falls fast. First generation electric cars, sold before 2016, needed a battery replacement at approximately 8.5%. Second generation cars, models such as the early Chevrolet Bolt EV and the early Tesla Model 3, replaced batteries at 2%. Modern cars, built from 2022 onward, replaced batteries at just 0.3%. Recurrent also reports what an actual capacity floor looks like in practice. Tesla guarantees the Model 3 Standard Range battery at 70% of original capacity for 100,000 miles or 8 years, whichever comes first.
Measured share of vehicles in the Recurrent community with a reported or confirmed battery replacement outside a major recall, by vehicle generation. Overall across the whole dataset, including cars more than 10 years old, the replacement rate is under 4%.
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| First generation before 2016 | 8.5 |
| Second generation early Bolt and Model 3 | 2 |
| Modern 2022 onward | 0.3 |
The floor every figure is measured against
A peer reviewed review of battery degradation research, published in the Journal of Environmental Management, states that the industry treats a battery as used up for its original automotive purpose once state of health falls to 70 to 80%. Every figure in this file clears that floor with room to spare, projected and measured alike, except the projection for heavy fast charging use, which at 76.0% sits closest to it.