Geotab has released updated findings from its third major study on EV battery degradation. The analysis draws on more than 22,700 electric vehicles across 21 makes and models, spanning several years of aggregated telematics information. The verdict: modern batteries remain robust, but charging behavior has emerged as the dominant factor in how quickly they age.
The study focuses on state of health (SOH), which measures a battery’s current capacity compared to its original capacity, and reveals that while the average degradation rate has returned to 2.3% per year, batteries remain durable enough to support extended vehicle lifecycles.
“Because we are in a unique position tracking EV data globally, we can aggregate findings to provide insights on overarching trends that help the industry answer critical questions about battery longevity and ROI,” Charlotte Argue of Geotab said in an interview with FreightWaves.
The research addresses one of the most pressing concerns in EV adoption: uncertainty about battery lifespan. Because the battery represents the most expensive component in an electric vehicle, understanding its degradation patterns is key. The battery itself directly affects return on investment and total cost of ownership calculations for fleets considering electrification.
“With any emerging technology, there are always more questions than answers,” Argue said. “For EV batteries specifically, questions like ‘How long is this battery going to last?’ or ‘How quickly will I lose capacity?’ are critical for both consumers and fleet operators.”
Battery degradation presents a more nuanced picture
The analysis shows an average annual battery degradation rate of 2.3%, up from 1.8% in the company’s 2024 study.
The 2.3% average annual degradation matches findings from Geotab’s initial 2019-2020 study.
Several factors explain the return to the higher figure: the latest study includes 21 models instead of 11, with a higher concentration of newer vehicles that typically experience faster initial degradation before the rate stabilizes.
More significantly, the data reveals a growing reliance on high-power DC fast charging.
“Our data shows that charging power and frequency are the strongest influences on degradation, but even for those using high-power charging frequently, the average degradation rate is still only 3% per year,” Argue said.
The study establishes charging power as the strongest operational influence on battery health. Vehicles that relied heavily on DC fast charging above 100 kW experienced degradation rates averaging 3.0% per year — roughly double the 1.5% rate observed in vehicles primarily using AC or lower-power charging.
The study debunked the widely circulated advice that EV owners should keep their batteries between 20% and 80% charge. Analysis showed that for day-to-day users who charge to 100% and then drive the vehicle, there is minimal impact on long-term battery health.
“We found that fully charging or depleting batteries doesn’t negatively impact long-term health for most users; it only becomes a problem if a vehicle sits in those extreme states for more than 80% of its total time,” Argue said.
The difference in degradation between users who cap charging at 80% and those who periodically charge to 100% proved negligible, suggesting the cautious approach may be unnecessary for most applications.
The analysis found that climate plays a moderate but measurable role. Vehicles operating in hot climates degraded approximately 0.4% faster per year than those in mild conditions.
High-utilization vehicles showed degradation rates approximately 0.8% higher than low-use vehicles. However, the productivity gains and return on investment from keeping vehicles in active service typically outweigh this penalty. The average battery is projected to retain 81.6% state of health after eight years.
Implications for EV fleets
For fleet operators, the findings support a balanced approach to charging infrastructure. Argue recommends that fleet operators “size the infrastructure to the application.” Vehicles with overnight depot dwell time can rely on lower-power charging, reserving high-power DC fast charging for operational demands that require rapid turnaround.
“The focus for fleets should be balance: reserve high-power fast charging for when it’s essential and use lower-power chargers whenever vehicles have sufficient downtime, like sitting overnight at a depot,” Argue said.
The data also suggests fleets may benefit from keeping EVs in service longer than traditional internal combustion engine vehicles. With fewer parts to repair and batteries lasting longer than initially anticipated, operators have an opportunity to reduce total cost of ownership by extending vehicle lifecycles.
“Because EVs have fewer parts to repair and batteries are lasting longer than anticipated, there is a real opportunity for fleets to keep these vehicles longer than gas cars, driving down total cost of ownership and increasing ROI,” Argue said.
