How long do electric car batteries last? What 10,000 electric vehicles tell us about EV battery life

How long do EV batteries last?

When we analysed EV battery health (and published the original results in this blog post) in 2019, we found EV batteries degraded, on average, at 2.3% per year. In 2024, we performed a new analysis and the results indicate that EV batteries have improved significantly, degrading at 1.8% per year on average.

Geotab research shows that EV batteries could last 20 years or more if they degrade at an average rate of 1.8% per year, as we have observed.

With fleet operators and managers under increasing pressure to reduce CO₂ emissions — from government mandates, investors, environmental groups, the public and other stakeholders, this is great news. The most impactful way for fleets to reduce emissions is to transition to electric vehicles, but despite significant performance improvements, fleets still lack confidence that EVs can replace light, medium and heavy-duty ICE vehicles. Data insights from telematics can give fleets the confidence they need to incorporate EVs.

For instance, recent Geotab data shows that:

• 75% of light commercial vehicles could be replaced by comparable EVs today.
• An EV could provide cost savings of £12,596.30 per vehicle over its life.

Better data makes more confident decisions

Fleets need reliable and current data like this on EV batteries, range, capabilities and costs to be confident that EVs can replace ICE vehicles. In this blog post, we’ll present our latest research to help fleets understand how EV batteries are performing in the real world and how EVs can fit into their operations and also support strategic objectives like environmental pledges and cost reduction.

EV battery performance and health are the keys to EV confidence

An EV battery is the most expensive component of the vehicle; for procurement decisions, it is critical to know how the battery’s capacity and health will change over time. The longer the battery life lasts, the more the EV can be used, and the more it’s used, the more savings fleets can see. 

See also: Podcast: EV myths and management with Charlotte Argue

What is EV battery degradation?

EV battery degradation is a natural process that permanently reduces the amount of energy a battery can store or the amount of power it can deliver. The batteries in EVs can generally deliver more power than the powertrain components can handle. As a result, power degradation is rarely observable in EVs and only the loss of the battery’s ability to store energy matters.

An EV battery’s condition is called its state of health (SOH). Batteries start their life with 100% SOH and over time they deteriorate. For example, a 60 kWh battery with 90% SOH would effectively act like a 54 kWh battery.

Do electric car batteries degrade?

Yes, like all batteries, EV batteries degrade. However, EV batteries are, on average, exhibiting high levels of sustained health — and battery degradation rates are improving in newer models.

Our latest research finds that EV batteries are degrading at 1.8% per year on average. The last time we analysed battery degradation in 2019, we found an average annual degradation rate of 2.3% (which was already quite good).

See figure 1 below for the battery degradation rates of the 11 EV models analysed.

Is EV battery degradation linear?

While our analysis shows more or less linear degradation, as a general rule, EV battery life is expected to decline non-linearly: an initial drop, which continues to decline but at a far more moderate pace. Toward the end of its life, drivers can expect to see a final significant drop in battery state of health, as seen in the chart below.

Figure 2: Expected battery degradation curve.

The Geotab EV battery degradation tool

In 2019, we produced our battery degradation tool allowing users to discover and compare degradation rates for various EV models. While the data the tool relies on is accurate, the tool itself does not include data since 2019.

Do electric car batteries wear out? 

Of course, like all batteries, EV batteries will eventually wear out, but in most cases, this will be long after the vehicle’s life-cycle is complete and the batteries may have a second or third life in different applications.

How often do EV batteries need to be replaced?

According to our data, the simple answer is that the vast majority of batteries will outlast the usable life of the vehicle and will never need to be replaced. If an average EV battery degrades at 1.8% per year, it will still have over 80% state of health after 12 years, generally beyond the usual life of a fleet vehicle.

However, as we expect EV battery life to decline non-linearly, there would likely be a more significant drop-off as the battery ages. We haven’t observed enough batteries reach the end-of-life drop (known as the “heel”) for us to predict when this drop is likely to occur. We will continue monitoring for the expected non-linear degradation.

Do electric cars lose range over time?

Yes, as an EV battery degrades, the vehicle’s maximum range decreases. For example, if you purchase an EV today with a 300-mile range, you would lose, on average, about 21 miles of range after five years and 45 miles after 10 years. This decline is not likely to have a significant impact on most drivers’ day-to-day needs, but it is a factor fleet managers will need to consider when it comes to maximising the value of their EVs.

(Other factors affect EVs’ day-to-day range, especially driving speed and temperature.)

Importantly for consumers, automakers commonly offer a warranty on EV batteries for eight years or 100,000 miles. This is the federal minimum in the United States and it varies by manufacturer and country. But by all accounts, electric car batteries should last much longer than that — even in high-use vehicles.

That’s the simple answer, but the question of how long does an electric car battery last is complicated and numerous factors determine EV battery longevity.

Common factors impacting electric car battery life

In general, today’s battery electric vehicles (BEV) and plug-in hybrid electric vehicles (PHEV) use lithium-ion batteries. Several key factors determine how long lithium vehicle batteries last and the rate at which their range declines. These include:

• Age
• Temperature
• Operating state of charge
• AC vs DC charging
• Usage (energy cycles)
• Battery chemistry
• Battery system and thermal management components 

How does temperature affect EV battery life?

Batteries exposed to hot days degrade faster than those in temperate climates

How much do temperatures affect EV batteries? Will an EV in Arizona have a different battery life than the same car driven in Norway? To find out, we grouped the vehicles based on the following climate conditions:

• Temperate: Fewer than five days per year over 27℃ or under -5℃
• Hot: More than five days per year over 27℃

As illustrated below in figure 3, vehicles driven in hot climates showed a notably faster rate of decline than those driven in moderate climates. This is not great news if you and your fleet toil under the hot sun but keep reading for best practices to reduce the impact of heat on your fleet.

Figure 3: Batteries exposed to hot days degrade faster than those in temperate climates.

How do vehicle make, model and year affect battery performance?

Our data shows that vehicle batteries respond differently to the test of time, depending on their make and model year. Why do some vehicle models, on average, degrade faster than others? Two potential contributors are battery chemistry and the thermal management of the battery pack.

While current EVs mostly use lithium-ion batteries, there are many different variations of lithium-ion chemistries and this will influence how it responds to stress. 

In addition to cell chemistry, temperature control techniques differ across vehicle models. A major distinction is whether the battery pack is cooled and/or heated by air or liquid.

Liquid cooling vs air cooling: which is better for EV battery longevity?

Let’s compare a vehicle with a liquid cooling system to one with a passive air cooling system: the 2015 Tesla Model S and the 2015 Nissan Leaf, respectively. The Leaf has an average degradation rate of 4.2%, while the Model S is 2.3%. Based on this comparison, good thermal management offers better protection against battery degradation.

Figure 4: Battery degradation comparison of 2015 Tesla Model S (liquid cooling) vs. 2015 Nissan Leaf (passive air cooling).

High EV use does not equal higher battery degradation

One exciting insight from our research is that high-use electric vehicles did not show significantly higher battery degradation than others. This should be welcome news since EVs offer better value the more they drive.

The takeaway? Don’t be afraid to put your EVs in high-use duty cycles. Their battery life won't be negatively impacted as long as they are within their daily driving range. One caveat: if high use requires routine DC fast charging, read the section below on the impact of charging type.

Figure 5: Amount of use has a small impact on average degradation rates (~0.25% over 48 months)

How do charging methods affect battery health?

Our analysis showed no significant impact on degradation rates when comparing high-use and low-use vehicles — when controlling for DC charging use. However, analysing the same vehicle model in a high-use situation exposed to different climates and charging power, we saw a strong correlation between high temperature climates, frequency of high power charge usage and battery decline.

We were able to look at the predominant charging level used for the EVs in our system. North American EV charging stations are categorised into three common types:

• AC Level 1 (120 volts) – half a regular home outlet in the UK
• AC Level 2 (240 volts) – typical for home or fleet charging
• Direct current fast charging (DCFC) – for faster top-ups

There is an observable difference in battery health between cars that routinely charge on Level 2 compared to those that used Level 1, but the difference is not statistically significant.

Figure 6: Battery degradation for vehicles that primarily charge on Level 1 compared with Level 2.

On the other hand, the use of DCFC equipment does appear to significantly impact the rate at which batteries degrade. Rapidly charging a battery means high currents, resulting in high temperatures, both of which strain batteries. In fact, many automakers suggest drivers and fleet managers limit the use of DC fast charging to prolong their electric vehicles’ battery life.

Below, we look at all battery electric vehicles operating in hot climate conditions based on how frequently they used a DCFC: never, occasionally (0-3 times per month) or frequently (3+ times per month).

Figure 7: Battery degradation appears to be strongly correlated with DCFC use for vehicles in seasonal or hot climates.

As part of our new analysis, we looked deeper into how these factors operate in combination. To investigate the relationship between charging power and climate, we examined all the vehicles of one model, and grouped them into four cohorts based on their exposure to different climates and DCFC charging frequency. We found that the vehicles operating in both higher temperatures and frequently using DC fast charging had a higher battery degradation rate — more than three times the average. (Note, this particular model has a higher-than-average power capability for DC charging, and therefore is not necessarily representative of all EVs.)

State of charge, charging buffers and their impact on EV battery lifespan

State of charge (SOC) refers to the amount of energy an EV battery currently is holding compared to its capacity. Simply put, a fully charged battery has a SOC of 100%; a discharged battery has a SOC of 0%; and a half-charged battery, 50%. However, the “usable” charge is different from the “absolute” charge. This is due to charging buffers. 

What is an EV battery charging buffer?

Since operating a battery near absolute full or empty has negative implications on battery health, automakers add buffers to prevent vehicles from reaching extreme high and low charge levels. The buffers artificially limit the vehicle’s charging capacity by manufacturer software settings (see chart below).

As a result, the methods used to control vehicles’ state of charge is another reason EV battery life differs among manufacturers.

Figure 8: Battery protection buffers control the usable state of charge window for an EV.

Thanks to over-the-air software updates, manufacturers can change the size of the buffer when needed, as discovered by some Tesla owners in 2019 when they noticed a decrease in their top range. Tesla confirmed the upgrade was “to protect the battery and improve longevity.”

Some automakers have adjustable charge ceilings, so the user can set their own maximum charge (e.g., they can tell the vehicle to stop charging at 75% instead of 100%). This owner-discretionary region (B in the chart above) works in combination with the non-discretionary buffer (A) to limit battery operation in areas of higher degradation. 

Consider how the Chevrolet Volt used buffers to increase the lifespan of its EV batteries 

The Chevrolet Volt (now discontinued) had comparatively large top and bottom protection buffers (regions A and D above) that dynamically changed as the battery aged. While the larger buffers meant less energy for driving, it resulted in a longer-lasting battery pack. Given the larger SOC buffers, liquid thermal management and dynamic (decreasing) buffer size, Volt users could expect slower-than-average degradation rates, and our data bear this out (as shown in figure 9 below).

Figure 9: Battery degradation over time for a Chevrolet Volt vs. all vehicles.

How to extend EV battery life

All of this data shows that, while some things are out of an operator’s control, there are best practices drivers and fleets can follow to extend the life of your EV batteries — and, by extension, your electric vehicles.

Turn down the temperature

The data on how temperature affects battery life tells us that exposure to heat is likely to make batteries degrade quicker and driving in moderate climate conditions is best for battery health. At moderate temperatures, batteries may even degrade slower than average. 

If you are deciding which vehicle to purchase, consider models with liquid cooling for the battery. For now, Geotab’s research appears to indicate that liquid cooling protects EV batteries better than air cooling.

Watch the charge

When it comes to EV battery charging best practices, we recommend fleets minimise DC fast charging. Some high-use duty cycles will need a faster charge, but if your vehicles sit overnight, Level 2 should be sufficient for most of your charging needs.

It’s also a good idea to avoid keeping vehicles sitting with a full or empty charge. Ideally, keep vehicles’ state of charge between 20% and 80%, particularly when leaving them unused for longer periods. Fleets can automate this task by using the adjustable buffer setting (if present). Reserve full charges for long-distance trips.

Put those vehicles to work

Do not hesitate to put electric vehicles to work. Our research finds that high use is not a concern for EV battery lifespan, so fleets can look for opportunities to reduce their total cost of ownership by maximising road hours. 

However, it is important to note that, for high-use vehicles, DC charging may cause EV batteries to degrade faster than average, especially if your vehicles operate in the heat.

Pay attention to your EV battery data

Accurate state-of-health information, made possible by comprehensive telematics data, is key to helping fleets make the best use of electric vehicles. Telematics data insights, like you’ll find in Geotab’s EV Battery Health report, allows fleets to know the real battery capacity of their EVs, understand the rate of degradation and get the most value from EVs throughout their life-cycle, so they can use their vehicles with confidence.

With these lessons learned, organisations can begin to apply them at a fleet-specific level to understand their own unique challenges and opportunities better. For example, providing fleet operators with tools to monitor EV battery health and operating conditions allows them to take preventive or corrective action for vehicles exposed to known factors that can accelerate degradation.

Conclusion: Operators can be confident that EV batteries will last as long as they need them

While EV batteries degrade at different rates depending on model and external conditions, our data indicate that most electric vehicles today have not experienced a significant decline in battery life. In 2019, we assessed the average EV battery degradation rate at 2.3% per year and the rate under ideal climate and charging conditions at an impressive 1.6%. In our most recent research, including many newer models, we found an average rate of 1.8% and the best performers declined only 1% per year or less.

So, how long do electric car batteries last? Numerous factors determine an electric vehicle battery’s lifespan, but on average, EV batteries will outlast the useful life of their vehicle, especially if drivers follow charging and driving best practices.

In sum, based on our research and real-world data, fleets should feel confident that many current EVs are suitable and cost-effective to replace a range of light, medium and heavy-duty ICE vehicles. 

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We are ready to answer your questions about EV battery health and fleet electrification. Get in touch here.

* Notes about the analysis:

• The degradation curves displayed are the average trend line from the data analysed.
• These graphs can offer insight into average EV battery life over time, but they should not be interpreted as precise predictions for any specific vehicle.
• A subset of vehicle makes, models and years are not available in the visualisation due to insufficient data.

Originally published on December 13, 2019. Updated August 29th, 2024.