EV batteries: Geotab study shows only slight degradation per year – charging behavior is key.

In its updated study on the state of EV batteries, the company analyzes real-world data on battery health from more than 22,700 electric vehicles across 21 brands and models, drawing on several years of aggregated telematics data. The updated analysis shows an average annual battery degradation rate of 2.3 percent, compared with 1.8 percent in 2024.

This slight increase reflects the changing usage of electric vehicles, particularly the growing reliance on high-powered DC fast charging devices. The lifespan of electric vehicles can pose a problem for both private users and fleet operators. But by understanding how batteries age under varying charging, climate and usage conditions, they can better manage vehicle performance, protect batteries, and make more informed decisions about the deployment of the vehicles and the charging strategy throughout the entire lifetime of the vehicles.

"The condition of the EV batteries remains good, even as the vehicles are charged faster and used more intensively," says Charlotte Argue, Senior Manager, Sustainable Mobility at Geotab. "Our latest data show that the batteries still far outlast the replacement cycles planned by most fleets. What has changed is that charging behavior now plays a much larger role in how quickly the batteries age, which gives operators the opportunity to counter long-term risks through intelligent charging strategies."

Charging power is becoming the dominant factor

The analysis shows that charging power now has the strongest influence on the condition and wear of batteries. Vehicles that heavily relied on DC fast charging above 100 kW exhibited degradation at a faster rate, averaging up to 3.0 percent per year, compared with about 1.5 percent for vehicles mainly charged with AC or at lower power.

Other factors, such as climate, had a smaller independent influence. Vehicles operated in hotter regions showed degradation about 0.4 percent faster per year than vehicles in temperate climates.

Farewell to strict charging rules?

The data also call into question the need for strict daily charging restrictions. Vehicles that regularly used a larger state-of-charge range did not show significantly higher degradation, unless the battery is regularly charged to full capacity or almost completely discharged.

More frequently used vehicles show slightly faster degradation, which is about 0.8 percent per year higher than the group with the lowest usage. However, this is an acceptable compromise in relation to the operational and financial benefits arising from continuing to operate the vehicles. For many fleets, these productivity gains directly translate to lower cost per kilometer over the vehicle's entire lifetime.

“For fleets, the emphasis should be on balance,” adds Argue. “Using the lowest charging power that still meets the operational requirements can make a measurable difference for long-term battery preservation without restricting the availability of the vehicles.”

What is battery degradation?

The degradation (loss of capacity) of batteries is a natural process that reduces the amount of energy a battery can store over time.

The state of the battery is measured as State of Health (SOH). Batteries begin their life with an SOH of 100 percent and gradually deteriorate. For example, a 60-kWh battery operated at an SOH of 80 percent behaves effectively like a 48-kWh battery.