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How long is that EV battery going to last? The one simple answer is that we don’t know for sure because electric cars have not been around long enough for us to tell. The best we can do is observe the apparent degradation in those cars on the road.
Even that observation can prove a challenge, though, since most EVs have been on the road well under six years, with almost 30% sold in 2022.
We still have very little sense of how they degrade over their lifetime - which car makers say should be as long as 20 years. So far, it seems that EV batteries have much longer lifespans than anyone imagined, since very few of them have been replaced, even once the 8-year, 100,000 mile warranty period ends.
Car makers say an electric vehicle should last 15 to 20 years
Why do we have to worry about battery degradation in EVs? Most electric cars rely on a high voltage lithium ion battery, which is the same sort of battery found in other household devices. Lithium ion batteries start to degrade as soon as they are made and that affects available range as cars age. It’s an unavoidable part of battery science that you probably noticed with your cell phone and your laptop. Even if you never use lithium ion batteries, they slowly lose power and efficiency over time.
The good news is that your EV battery is far more complex and sophisticated than other lithium ion batteries in your life and is built to ensure its lifetime exceeds its warranty - and more.
Coming up with an exact answer to what a battery lifetime is complicated because:
- Batteries are complicated systems. We can't observe them directly, and have to rely on a computer interface to give us information about their state of health, state of charge, and more.
- We know more about battery cells than battery packs. Most of the rigorous scientific tests on lithium ion batteries are done on individual battery cells, not the high-tech systems used in EVs.
But a lot of information can be gleaned from studies on older models of Nissan LEAF and Tesla Model S, both of which have been on the road for almost a decade. The study findings are encouraging: it looks like EV batteries have a lot of life in them.
Most EV batteries are still in cars
There have been two major battery recalls in recent years, both related to similar battery pack flaws in the Chevrolet Bolt EV and EUV and the Hyundai Kona Electric. The remedy for both of these recalls was a sweeping battery replacement program covered by the manufacturers. Other than these two recalls, though, battery replacements in the Recurrent community remain rare.
In the charts below, we show the number of owner-reported battery replacements in the Recurrent community of around 15,000 drivers:
Other than the two notable cases of manufacturer warranties, the LEAF and the Model S unsurprisingly have the highest percentage of battery replacements, since they are some of the oldest models in our fleet. However, it is important to note that the cars in the Recurrent fleet may skew newer than the average age of cars on the road. This is especially true for the Nissan LEAF, since early models lack the telematic services that we use for our data connection.
Below, we look at the same battery replacements by model year. Older cars generally do see more battery replacements than newer ones.
The peak in 2017 battery replacements is due to the Chevrolet Bolt recall, in which the battery replacement priority was given to 2017 models. Similarly, the Hyundai Kona EV recall was for 2019 and some 2020 models, which explains the spike in 2019.
We saw increased numbers of non-recall battery replacements in:
- 2013 Tesla Model S (8.5%)
- 2014 Tesla Model S (7.3%)
- 2015 Tesla Model S (3.5%)
- 2011 Nissan LEAF (8.3%)
- 2012 Nissan LEAF (3.5%)
If you have an older EV and are curious about the battery replacement process or cost, we have info for you!
About the data: Recurrent tracks battery replacements over time based on recall status, owner self-reports and by observing unusual jumps in vehicle range that often indicate replacement events. Our community is not representative of all EVs on the road due to limited data connectivity for some makes and model years.
Battery data from real cars
Below, we share data showing how EV range changes with time using real-world observations from our community of around 15,000 drivers. These charts show how the projected range at 100% charge changes with odometer. Note that we use odometer as a proxy for age of the vehicle, since the manufacture date of the batteries and vehicle is not known.
In the charts below, the shading around the darker, center lines indicates the standard deviation of our data. That means that most vehicles will exhibit range estimates that fall in the shaded portion. The darker, center line is the average of all the data.
You may also notice some wiggles at the beginning of each curve. This is generally due to having less data on cars with very few miles.
Nissan LEAF
Nissan LEAF is the oldest mass produced EV still on the road, has seen the most battery replacements. However, many of the replacements for early model year LEAFs were covered by Nissan after they found that their original battery chemistry lost charge quickly in hot environments. However, they quickly changed to a more hearty battery that has seen great success.
In fact, in response to a question about how the company planned to use old LEAF batteries, Nic Thomas, Nissan’s marketing director for the UK, told Forbes, “Almost all of the batteries we’ve ever made are still in cars, and we’ve been selling electric cars for 12 years. We haven’t got a great big stock of batteries that we can convert into something else.” Other comments from the company include one from 2019 by managing director of Renault-Nissan Energy Services, Francisco Carranza, who estimated that the batteries may last 22 years.
Tesla Model S
Tesla's Model S is the second earliest mass market EV, so it makes sense that its battery replacement numbers are higher than those of later model year Teslas. Although the degradation curve for the100 kWh Model S perfectly matches the beginning of the idealized battery degradation curve, the same is not true for Model S with a smaller battery pack.
We wrote an entire article about Tesla battery replacements and associated costs. You should be able to find anything you want to know in that article!
Tesla Model 3
The Tesla Model 3 has been on the road since 2018 and also exhibits a classic drop off in projected range over the first 20,000 miles before the trend levels off. Note that wiggles in the data, such as range increases at 60K, 80K, and 90K miles in the 62 kWh model, reflect changes in our computer simulations and changes in Tesla software, not actual increases in range.
BMW i3
Despite their smaller battery pack and a range that would be low by modern standards, the older BMW i3 battery packs have held up fairly well. The smallest, a 22 kWh pack, was released in the US in 2014. The 33 kWh packs were introduced in 2017. Both have, on average, hit 100,000 miles with around 80% of original capacity remaining. The more recent 42 kWh packs were released in 2019 and were likely purchased more as daily drivers, and thus have lower mileage. However, assuming a similar battery chemistry, the degradation should be similar to that in smaller packs.
Chevrolet Volt
Chevy's Volt is a plug-in hybrid vehicle, which tends to see less battery degradation due to more gentle use and a lower percentage of usable capacity than fully electric batteries. However, it’s still good to look at since we have a decent sample of high mileage cars.
Models to Keep an Eye On
The Hyundai Ioniq 5 and Ford Mustang Mach-E and are newer models in the EV world, but have both gotten a lot of attention. We are carefully watching how their range changes over time. This will be particularly interesting because both models come new with free fast charging. As Recurrent works to understand the long term effects of fast charging on range degradation, we will hone in on vehicles that have relied heavily on DC charging.
What warranties say about batteries
Another way we can understand the expected lifespan on major EV batteries is by seeing how long the manufacturers guarantee them. EV warranties are much like other car warranties, except for the part about the battery! And since the battery is so important, make sure you read your specific warranty carefully. For used cars that are out of warranty, supplemental protection may be available from the manufacturer or from third parties.
The standard warranty in the US is 8 years or 100,000 miles, but manufacturers can decide what percentage of original battery capacity is ensured over that time. Getting at the actual battery capacity is not always easy, and manufacturers often want their service centers to verify faulty packs. However, these warranties set the expectation that a battery should retain a certain amount of energy over a fixed period of time.
Sample manufacturer warranties
- Tesla battery warranties vary a bit between the Model 3 Standard Range, Long Range and the Model S/X. The Model 3 Standard Range battery is guaranteed to stay at 70% original capacity for 100,000 miles or 8 years, whichever happens first. Other trim levels of the Model 3, and Tesla’s Model Y have a 70% guarantee to 120,000 miles or 8 years. The Model S and X have the same 8 years but 150,000 miles.
- Chevy (GM) has a standard 8 year, 100,000 mile warranty for “electric propulsion components” of the Bolt, Volt, and Malibu. It acknowledges degradation of 10-40% is possible over the warranty period.
- Hyundai boasted “America’s Best Warranty” between 2012 and 2019 with a lifetime, albeit non transferable, battery guarantee. The warranty is against failure, which is largely unspecified in documentation. From 2020 onwards, the battery is guaranteed to maintain 70% of capacity for 10 years or 100,000 miles.
- BMW guaranteed 70% original capacity for 8 years or 100,000 miles, transferable to new owners.
- VW guaranteed 70% original capacity for 8 years or 100,000 miles.
These warranties should reinforce that EV batteries last for quite a while, and as technology improves, we should expect to see batteries that will show only slight degradation over decades or hundreds of thousands of miles. Maybe the million mile battery is out there!
Battery health and how to protect it
Lithium ion batteries have been studied a lot. While most of the scientific foundations for this understanding comes from laboratory experiments on battery cells, the principles generally hold for the larger packs used in cars.
Batteries generate energy via chemical reaction. Since the chemical reactions happen in a physical cell, unwanted or waste reactions also occur. This is unavoidable and it doesn’t mean there’s anything wrong with the battery. Some of these side reactions can even help the battery last longer, if other conditions are favorable. The best practices to avoid battery degradation are things that either reduce the physical stress of the chemical reactions on the battery or avoid things that speed up the chemical reactions.
Heat
Early LEAF batteries taught us something important about the longevity of lithium batteries -- they do not like the heat. The earliest LEAF batteries had no active coolant, meaning that EVs in hot climates degraded more quickly than expected and many did need to have a battery replacement. Although many automakers learned from Nissan’s early misstep and installed thermal management in their battery packs, it is still true that batteries last longer if they are kept as cool as possible. Since not all thermal management systems operate the same, this means parking in the shade, cooling your car before charging, and considering more active cooling if you live in a hot climate.
Charging
Charging your battery is a physical process that moves lithium ions and electrons around in the cells. At faster charging rates, the physical processes happen more forcefully, and the more physical stress or micro-damage occurs to the battery materials. With very high voltage charging, such as DC fast charging, a lot of heat is also generated, which is not ideal for battery longevity. DC fast charging is the double bacon cheeseburger of charging: great on a road trip but best to avoid everyday. Most batteries are built for regular Level 2, or 220V charging.
Depth of discharge
Depth of discharge refers to how much battery you use in between charges. For instance, if you have a 100 kWh battery, a 80 kWh depth of discharge is 80% of the battery capacity. Laboratory studies show that battery cells last much longer if the depth of discharge is small, and conventional wisdom suggests keeping charge in the band around 50%, where the battery is chemically most stable. In other words, rather than using 50% of your battery before recharging, you might use 20% of the battery, recharge, and then use another 30%.
Monitoring your EV battery
For EV owners, Recurrent offers battery monitoring that checks several battery stats each day to compare them to thousands of similar vehicles. For used car shoppers, Recurrent offers free EV condition reports for cars at hundreds of dealerships across the US.
Battery second life
The big question that drops out of the conversation about battery life is what comes next for all these lithium ion batteries. The material and labor that goes into fabricating them is not insignificant, and many of the chemicals are expensive, toxic, and difficult to extract and reuse.
What can car manufacturers do with old EV batteries, and what will happen to the mountains of batteries that are used in future EVs?
One consideration is that as batteries degrade, they reach a point where they are no longer useful for cars, but they still can store and generate electricity for other uses that don’t require the same power. Nissan has projects to use old LEAF batteries to power streetlights, and GM uses batteries to back up data centers in Michigan. There is hope that linking together older EV batteries will provide storage for renewable energy, support grid resilience, or serve as emergency backup power. As vehicle manufacturers devise plans to repossess and reuse batteries, they may find themselves expanding into other industries and working to electrify more than just vehicles.
Has your EV had a battery replacement?
Electric cars with battery replacements provide a lot of insight on the past, present and future of EV batteries. If you have one, please consider contributing some of that valuable information to the Recurrent driver community!
