The transportation and logistics industry is currently undergoing a fundamental shift in an effort to become more sustainable. Central to this shift is the transition to electric fleet vehicles (EVs). Fleet electrification is accelerating rapidly, a trend that will only intensify as the urgency of the climate crisis deepens. This is no longer a distant prospect, it is a present reality that calls for immediate action.
Yet, these modern vehicles introduce new uncertainties for fleet managers, particularly regarding the health and degradation of EV batteries. Much like mobile phone batteries, EV batteries deteriorate over time, prompting questions about their longevity and the implications for fleet performance and operational efficiency. This guide addresses the key concerns fleet managers are now facing, including what a typical degradation curve looks like in practice.
What is EV battery degradation?
Battery degradation refers to the gradual and permanent reduction in a battery’s ability to store energy. In other words, its energy capacity diminishes over time. This is a natural and unavoidable process, driven by the physical and chemical changes that happen within the battery’s lithium-ion cells, which begin to degrade from the moment they are manufactured.
The term state of health (SoH) is used to describe the current condition of a battery. Expressed as a percentage, SoH indicates how much energy the battery can still deliver, measured in kilowatt-hours (kWh). A new battery starts with a 100% SoH, which steadily declines throughout its lifespan.
It’s important to note that SoH does not directly equate to vehicle range. Several other factors determine how far an EV can travel, including driving behaviour, cargo load, use of auxiliary systems, charging habits, and environmental conditions.
How do EV batteries degrade?
EV battery degradation occurs through two primary processes: calendar ageing and cycling ageing.
- Calendar ageing: refers to the gradual decline in battery performance over time, even when the vehicle is not in use. It is influenced by factors such as temperature, the battery’s charge state, and the duration it remains idle.
- Cycling ageing: results from the repeated charging and discharging of the battery during regular use.
Both forms of degradation are inevitable, which understandably raises concerns for fleet managers. Usually, an EV battery is considered to have reached the end of its useful life when its state of health (SoH) falls to around 70%.
However, many batteries continue to function reliably beyond this point. In addition, most EVs are backed by long-term battery warranties, offering reassurance over the vehicle’s operational lifespan.
How long does an EV battery last?
Most EV batteries carry a warranty of around 8 years or 100,000 miles, guaranteeing a minimum state of health within that period. Actual expected lifespan tends to run considerably longer, commonly cited in the range of 15 to 20 years, with manufacturers' battery management systems designed to slow degradation well beyond the warranty period. That said, providing a definitive answer to this question is challenging, as battery longevity depends on several interrelated factors. Influences on battery degradation include:
- Frequency of use.
- Driving style (e.g. speed, acceleration, braking).
- Ambient temperature and climate.
- Typical state of charge (e.g. regularly kept near full or low).
- Age of the battery.
- Frequency and depth of charging and discharging.
As a result, the long-term health of a lithium-ion battery can vary significantly between vehicles and must be assessed on a case-by-case basis. Although, treating an EV with care, such as avoiding excessive fast charging, maintaining moderate charge levels, and driving smoothly, will almost certainly extend its lifespan.
Does EV battery health impact depreciation?
Given that vehicle acquisition and disposal are key areas of focus in fleet management, a relevant question is whether battery health affects an EV’s residual value.
Consider two vehicles in otherwise similar condition: one with a battery at 70% state of health (SoH), and the other at 90%. In this instance, the vehicle with the healthier battery would command a higher value.
This highlights the importance of having reliable fleet data on battery condition because a lower SoH doesn’t always tell the full story. For example, a battery with fewer rapid charging cycles may degrade more slowly and retain greater long-term value.
It’s also worth noting that lithium-ion battery costs, the most expensive component of an EV, continue to fall. This benefits fleet managers when it comes to resale or repurposing. Moreover, these batteries often have a valuable second life in domestic and industrial energy storage applications, further extending their usefulness beyond the vehicle itself.
What does battery degradation mean for warranty and replacement cost?
Most new EVs come with a battery warranty separate from the general vehicle warranty, typically covering a set number of years or miles and guaranteeing the battery will not fall below a stated state of health within that period. Terms vary significantly between manufacturers, so it is worth checking the specific warranty for any vehicle you are adding to the fleet rather than assuming a standard figure.
If a battery does need replacing outside warranty, cost depends on the vehicle, the battery size, and whether the whole pack or individual modules need replacing. As with most EV components, prices have been falling as the technology matures and the market grows, but a replacement remains a significant cost, which is part of why tracking degradation proactively, and catching a fault before it becomes a full replacement, is worth the effort.
Can fleet managers extend EV battery life?
Yes, since battery degradation is heavily influenced by usage, fleet managers play a crucial part in preserving EV battery health. As fleet electrification advances, so too does the supporting technology.
Modern fleet management systems give visibility into temperature exposure, helping fleet managers spot charging patterns or conditions that put batteries under thermal stress. This is important, as high temperatures dramatically accelerate battery degradation.
Additionally, best practice involves keeping the battery within a moderate charge range, broadly 20% to 80%, rather than routinely charging it to full capacity or running it down to empty, while avoiding full discharge and consistently using rapid charging, both of which can shorten an EV battery’s lifespan.
Turning battery data into a management practice
Two otherwise-identical vehicles in the same fleet can end up with meaningfully different battery health after the same distance, driven by climate, charging habits, and how much time they spend parked at a high state of charge. That gap is closed by visibility, not by buying a different vehicle.
With cloud-based fleet management software, charging behaviour, state of charge, and temperature exposure become things a fleet manager can see and act on, rather than something that only shows up as a lower resale value years later. Our EV transition and management solution is built around exactly that kind of visibility.
We at MICHELIN Connected Fleet are proud to be leading the way in EV fleet management. Our solutions are geared to help protect the battery health of electric fleet vehicles for the long term, so that sustainability coincides with efficiency. If you’re interested in how our fleet management solutions can help, then be sure to make an enquiry into our services today.
Frequently asked questions
How much does an EV battery degrade?
It varies by vehicle and usage, but a commonly cited industry figure is around 2-2.5% capacity loss per year under typical conditions, with the rate often slowing after the first few years. Climate, charging habits, and calendar age all affect the real-world number more than mileage alone.
At what percentage is an EV battery considered degraded?
There is no single legal or technical cutoff, but a state of health around 70% is commonly used as a practical reference point for end of useful life. Many batteries continue to perform reliably below that figure, and most EVs carry a battery warranty that guarantees a minimum state of health for a set period regardless.
Does fast charging damage EV batteries?
Yes, frequent high-power fast charging is widely associated with faster degradation, alongside sustained heat exposure and regularly charging to 100% and leaving the vehicle parked. Occasional fast charging isn't a major concern; it's the proportion of a vehicle's charging sessions that rely on it over its lifetime that matters.
Can EV battery degradation be reversed?
No. Degradation at the cell chemistry level is not reversible through operational changes. What can be controlled is the RATE of further degradation, through charging discipline, thermal management, and avoiding extended time at extreme states of charge.
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