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Fast Charging Vs. Slow Charging: Study Reveals Difference In Range Degradation

Iulian Dnistran

Aug 29, 2023

Recurrent Auto analyzed the data from over 12,500 Tesla vehicles in the United States.

One of the thoughts that go through the mind of an EV owner has to do with the impact that DC fast charging will have on the vehicle’s high-voltage battery in the long run. In other words, how much will the battery degrade over time if fast charging is used predominantly?

Well, according to a recent study from Recurring Auto that analyzed charging data from over 12,500 Tesla vehicles in the United States, the rate of range degradation is statistically similar when compared to AC charging.

The company, which provides vehicle and battery analysis reports for EVs, compared cars that fast charge at least 90 percent of the time to cars that fast charge less than 10 percent of the time, and the results show little to no difference between the two charging methods.

The charts below show the percentage of the original range as shown on the cars’ dashboards – in this case, the Tesla Model 3 and Tesla Model Y – and the number of days.

Choosing between DC over AC isn’t the only thing that can affect the battery in the long run, with factors such as extreme temperatures and very low or very high states of charge also playing a big role in the big scheme of things.

However, as Recurrent’s results show, the robust thermal, voltage, and battery management systems that EV makers have invested in do protect their batteries from damage with routine fast charger use.

To help the battery last as long as possible, using the preconditioning feature is of utmost importance, both in extreme heat and in extreme cold, as this brings the cells to the optimal temperature before plugging in the charging connector. Another tip is to avoid fast charging at very low states or very high states of charge, as battery resistance is higher at these levels and puts additional stress on the battery.

Another study from 2020 found that battery-powered vehicles, including EVs and PHEVs, encountered battery degradation anywhere from zero percent to 4.1 percent in the first year, with the best-performing model being the 2019 Chevrolet Bolt EV and the worst being the 2019 Mitsubishi Outlander PHEV.

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