Battery life: how many miles of range do electric cars lose over the years?

The lifespan of batteries is a deterrent to buying an electric car. It must be said that if a complete pack needs to be replaced, the operation can cost more than €10,000. However, apart from manufacturing defects, batteries do not fail overnight. However, there is a chemical phenomenon of degradation of their capacity, and therefore of their autonomy, which a new study allows us to estimate over the years.

Canadian telematics data analytics company Geotab has once again looked into the question, after an initial study published in 2019.

Eleven models were analyzed, but Geotab preferred not to name them, from a sample of 10,000 electric vehicles, a priori all used in North America. Analysts observed an average degradation of their battery capacity of 1.8% each year, compared to 2.3% per year in the first study in 2019. For a model with a range of 500 km, this would represent 9 km of range lost each year.

After twelve years, electric vehicle batteries would have retained 80% of their initial capacity. This is called SoH (state of healthor state of health which expresses the capacity of a battery compared to its initial capacity). For Geotab “the vast majority of batteries will last longer than the useful life of the vehicle and will never need to be replaced”. A 20% reduction in autonomy over twelve years is not negligible, however. A model capable of covering 500 km when it leaves the factory would thus see its range reduced to 400 km.

A deterioration that depends on many factors

Many factors can influence this degradation, which is not linear. “As a general rule, the life of an electric vehicle battery should decrease in a non-linear manner: an initial decline, which continues, but at a much more moderate pace”explains Charlotte Argue, who signed this study.Towards the end of its life, the driver can expect a final significant drop in the battery's health status”.

If Geotab has chosen to study the degradation of battery capacity over the years, the mileage traveled is also important. Indeed, the more miles an electric car has, the more charge/discharge cycles it has undergone. For Geotab, however, this impact would be moderate. Thus, over four years, models having traveled more than 20,000 km per year would see their battery degrade only 25% faster than those whose annual mileage is less than 8,000 km.

Among other degradation factors, temperature plays a very important role. Thus, between cars operating in a temperate climate zone (less than five days per year at more than 27℃ or less than -5℃) and models used in hot climates (more than five days per year at more than 27℃), the degradation of the SoH could be twice as fast for the latter.

DC fast charging can also drain an electric vehicle's battery faster. Between a model that charges only with AC power, at lower power, and one that experiences more than three fast charges per month, the latter could see its battery capacity decrease nearly twice as fast in hot climates, Geotab says.

Finally, Geotab recommends maintaining a charge level between 20 and 80% as often as possible, especially if a vehicle is not going to be used for long periods of time.

Not all models are created equal

However, not all models are as prone to these degradation factors. For example, cars with liquid-cooled batteries, which are the vast majority today, are more resistant to high temperatures.

Battery chemistry is also very important. LFP batteries, which are becoming increasingly popular, are known to support 100% charges better than NMC batteries. According to a recent study published in the Journal of The Electrochemical Societythey would not be totally insensitive to it.

Even among models equipped with the same battery technologies, significant differences may exist, particularly depending on the management operated by the BMS (battery management systemor battery control system).

Geotab still offers to compare the battery capacity degradation observed across different models, but the data has not been updated since 2019. The cars being compared are therefore older generations.

According to data collected by Geotab in 2024, the best-placed electric car models would have lost only 1% of battery capacity after two years, compared to 6% already for the most impacted model.

Note that most electric cars guarantee their battery for up to eight years or 160,000 km (legal minimum in the United States) for a certain minimum SoH, for example 70%.