As recently as 5 years ago, Geotab experts discovered that electric car batteries wear out on average by 2.3 % per year. Even then, this fact was "surprisingly good news" for fans of electric cars.
A recent analysis involving a sample of 10,000 electric vehicles found that battery quality has improved over the years, and seriously so. Now, on average, batteries only degrade at 1.8% per year.
Geotab concludes that at this rate of degradation, electric car batteries could last 20 years or more. If the battery degrades at 1.8% per year, it will be more than 80% good after 12 years, the average life of a car.
Battery degradation is a normal result of use: any mobile phone owner can confirm that the level of charge you have left at the end of the day decreases significantly from the moment of purchase and after 2-3 years of use.
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As Geotab explains, a 60 kWh battery that starts life at 100 percent state of health (SoH) and then degrades to 90 percent health will “perform as efficiently as a 54 kWh battery”.
Although the 1.8% degradation rate is relatively good, the overall degradation of the battery is expected to decrease non-linearly, meaning that after an initial decline and stabilization period, the battery will experience a steeper decline towards the end of its life.
Eventually, more data will lead to more concrete conclusions about the battery's behavior at the end of its life, but for now, Geotab believes the batteries will outlast the car itself, especially if drivers follow safe charging practices and driving.
Geotab also found that high-use EVs did not experience significantly higher battery wear compared to other vehicles, and that fleet managers need not worry about subjecting their EVs to heavy duty cycles.
However, when analyzing the same vehicle model under conditions of intensive use in different climates and with different charging capacities, experts see a strong correlation between high temperature climates, the frequency of using high charging capacities and the reduction of battery charge.
Similarly, they found a noticeable difference in "health" of battery between cars that typically charge at level 2 compared to those that use level 1, but this difference is not statistically significant.
„Fast battery charging means high currents, which leads to high temperatures, both of which stress batteries. In fact, many automakers are suggesting drivers and fleet managers limit the use of DC fast charging to extend the life of their EV batteries, the company says.