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2019 tesla model 3

Michael SimariCar and Driver

  • Battery packs in electric vehicles slowly lose capacity to store energy over time.
  • Our long-term Tesla Model 3 has so far lost 7 percent of its capacity over 24,000 miles.
  • All EVs have lengthy warranties on the battery pack to assuage buyers’ potential fear of expensive replacement costs.

    Much like the little lithium-ion pack in your cellphone, the battery in an EV slowly loses its ability to store energy over time. In the case of an electric car, this degradation in its total energy capacity means that its maximum range shrinks over time. There are many factors that play into this. Some are choices by the various automakers (such as how much of the battery’s total capacity to make available; narrower swings in the state of charge are friendlier to longevity) and some based on the owner’s behavior. For example, our long-term Tesla Model 3 specifies that charging above 90 percent shouldn’t be done for daily use, only for trips, although it doesn’t explicitly say what the long-term ramifications might be for regularly going above that threshold.

    We were of course curious to see how our car’s pack is faring over time, and the geektastic TeslaFi software we’ve used to track our car’s more than 24,000 miles and each of the 842 times we’ve plugged it in has an answer. (Seriously, if you have a Tesla, sign up for TeslaFi.)

    TeslaFi’s battery-tracking tool puts our pack at 93 percent of its original 75.0-kWh capacity, a loss of