Modern electric vehicle (EV) batteries are continuing to show robust long-term performance despite rising dependence on rapid charging, according to a major new dataset released by Geotab. However, the analysis also reveals a clear shift in what most affects battery ageing — charging power, rather than climate or day-to-day state of charge, is now the dominant external factor shaping long-term battery health.
The updated study, published ahead of Geotab’s 25th anniversary, draws on real-world telematics information from more than 22,700 EVs across 21 models. It represents one of the largest ongoing multi-brand assessments of battery performance in commercial and public-sector fleets. The company’s latest findings put the average annual battery degradation rate at 2.3%, up from 1.8% in its 2024 analysis.
But the rise, Geotab stresses, is not a sign that today’s EV batteries are regressing. Instead, the change reflects how newer vehicles are being used, especially the expansion of high-power DC fast charging (DCFC) and the increasing operational intensity of fleet EVs. As Charlotte Argue, Senior Manager for Sustainable Mobility at Geotab, puts it: “EV battery health remains strong, even as vehicles are charged faster and deployed more intensively. What has changed is that charging behaviour now plays a much bigger role in how quickly batteries age.”
Charging power emerges as the leading determinant
The clear headline from the 2025–26 data is that fast charging above 100 kW imposes materially greater stress on battery cells, even when used relatively sparingly. Vehicles that relied heavily on high-power DC fast charging — defined in the report as those with more than 40% of DCFC sessions exceeding 100 kW — saw degradation rise to an average of 3.0% per year. By contrast, vehicles that primarily used AC charging or lower-power DC sessions aged at roughly half that rate, around 1.5% per year .
The difference is stark in Geotab’s modelling. Vehicles predominantly using lower-power charging are projected to retain around 88% of their original battery capacity after eight years, compared with just 76% among high-frequency, high-power DCFC users. These figures chart a widening gap in state-of-health (SOH) trajectories over a vehicle’s early lifecycle depending on charging behaviour.
Crucially, faster charging frequency alone is only part of the picture. The dataset shows that power level matters just as much as how often DCFC is used. EVs with frequent DC fast charging but largely staying below 100 kW degraded at a mid-range rate of 2.2% per year — significantly worse than those relying mostly on AC, yet still notably better than the highest-power cohort.
The shift mirrors broader market behaviour. Both the prevalence and the peak power of DCFC sessions have climbed steadily over the past five years, with average fast-charge power rising from around 70 kW in 2020 to above 90 kW in 2025 . With many new EV models able to accept 150 kW or more, high-power DC charging’s role in everyday fleet operations is rapidly expanding.
Argue notes that this change represents both an opportunity and a risk. “Using the lowest charging power that still meets operational needs can make a measurable difference to long-term battery health without limiting vehicle availability,” she says. For fleet operators, this reinforces the value of “strategic sizing” — selecting charging infrastructure and power levels aligned to real-world duty cycles rather than simply opting for the fastest available option.
Climate effects remain real but secondary
The report also analyses the influence of ambient temperature on ageing. While heat is a well-documented stressor on lithium-ion cells, Geotab’s real-world data shows the effect to be significantly smaller than the impact of high-power charging. Vehicles operating in hot climates — defined as experiencing more than 35% of days above 25°C — degraded only around 0.4% faster per year than those in mild environments .
The study notes that modern thermal management systems have mitigated much of the heat-related stress that earlier-generation EVs faced. However, geographic variation still matters. Operators in hotter regions may need to consider practices such as shaded parking, timed charging during cooler hours or staggered utilisation during heatwaves.
Interestingly, the report lacked enough vehicles in consistently cold climates to draw firm conclusions about low-temperature impacts over the long term.
SOC ‘rules’ matter less than many believed
One of the most surprising findings challenges a long-standing convention of EV ownership: the belief that drivers should routinely stay within a 20–80% state-of-charge (SOC) window to protect battery longevity.
Using telematics data to analyse vehicles’ cumulative time spent at high (>80%) and low (<20%) charge levels, Geotab found that moderate exposure to SOC extremes — up to around 80% of total cumulative time—had essentially no meaningful effect on ageing. Degradation rates in these low-exposure and medium-exposure groups were virtually identical at 1.4% and 1.5% per year respectively, as shown below.
Only when vehicles spent more than 80% of their time at very high or very low SOC did degradation accelerate significantly, rising to 2.0% per year. The report attributes this distinction partly to the protective “buffering” built into modern battery management systems. A displayed 100% charge is not chemically full, and a displayed 0% is not fully empty — meaning the real cell-level stress at these extremes is lower than the dashboard implies.
For everyday drivers and fleet managers, this finding may come as a relief. Strict SOC micromanagement appears unnecessary for most scenarios, provided vehicles are not left idle for prolonged periods at very high or low charge.
Utilisation: higher wear, but outweighed by operational value
Another operational factor, utilisation intensity, does correlate with degradation — though the influence is modest. Geotab measures utilisation via the number of effective charge cycles a vehicle completes in daily operation. Vehicles in the highest-use category, equivalent to a full cycle every one to two days, degraded around 0.8% faster per year than low-use vehicles that completed the equivalent of one cycle every week or more .
This brings high-intensity vehicles to an average of 2.3% annual degradation, versus 1.5% for the lowest-use group. Yet even at this rate, high-use EVs are projected to retain more than 81% SOH after eight years, indicating that batteries remain fit for purpose across normal fleet lifecycles.
Geotab notes that the productivity gains from higher utilisation typically outweigh the incremental battery ageing costs. For operators seeking improved return on investment and increased revenue miles, prioritising vehicle deployment remains a rational strategy — so long as fast-charging reliance does not increase disproportionately.
Design and chemistry still matter
Although the study focuses on external operational factors, it emphasises that intrinsic differences in battery chemistry, pack configuration and thermal management systems also drive significant variation across models. The report illustrated how different vehicle classes — multi-purpose vehicles, cars and trucks — show markedly different average SOH trajectories, with vans degrading faster on average than passenger cars .
These variations underline that fleet-level strategies must be tuned to the specific models in service, not just generic EV guidance.
Data-driven decisions for long-term fleet health
The broader message from the updated study is one of reassurance mixed with actionable nuance. EV batteries are holding up well — still lasting far beyond typical replacement cycles — but the variables shaping their ageing are evolving.
As Argue concludes: “Our latest data shows that batteries are lasting well beyond the replacement cycles most fleets plan for. Charging behaviour now plays a much bigger role in battery ageing, giving operators an opportunity to manage long-term risk through smart charging strategies.”
For fleet operators, this increasingly means telematics-led decision-making: tracking battery SOH, identifying high-stress charging patterns, and calibrating fast-charging use to true operational need rather than convenience. With EV adoption accelerating across commercial segments, such evidence-based management could prove essential to safeguarding residual values, controlling total cost of ownership and ensuring high-uptime fleet performance in the decade ahead.
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