A sign offers parking and charging facilities for electric cars at a retail park in Berlin in 2023. Evidence from the oldest generation of electric vehicles suggests their batteries are lasting longer than was expected in the early days of the EV industry.
Odd Andersen/AFP
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Odd Andersen/AFP
Fifteen years ago, when modern electric vehicles were just hitting the road, no one knew exactly what to expect from their giant, expensive lithium-ion batteries.
As batteries age, they hold less and less power. Anyone who’s ever had a dying smartphone, or had to replace a vehicle’s 12-volt starter battery, knows this painfully well.
EV batteries were intended to last longer than those smaller, cheaper batteries. But how much longer?
The predictions were not soothing. In 2010, the New York Times wrote that “estimates of [EV] battery packs’ lifespan — no one knows for sure — range upward from seven years.” The average car on the road is more than 12 years old. And that discrepancy made some would-be EV buyers nervous.
Batteries come with warranties, but they don’t last as long as the car. If a high-voltage battery chokes out midway through a car’s life, it needs replacing — at a price tag that can run in the ballpark of $5,000 to $20,000.
But there’s good news.
As the fleet of EVs on the road ages, new data pooled from tens of thousands of vehicles is showing those batteries are lasting longer than expected.
How a battery ages
Lithium-ion batteries undergo two kinds of aging. First, there’s calendar aging: They degrade as time goes on, holding less juice, even if they just sit in storage.
Then there’s cyclical aging, which is how much a battery degrades based on its use — being charged and discharged, over and over again.
That means there’s no way to dodge degradation. Whether you use a vehicle a lot or a little, eventually, the battery will hold less power.
But the trajectory of aging isn’t a straight line. Recurrent, a research firm that pulls in data from over 30,000 EV drivers, describes it as an “S curve.” There’s a rapid decline at the beginning, a long leveling off, and then a more rapid decline at the end.
“It’s very much like breaking in a pair of shoes,” says Liz Najman, the director of market insights at Recurrent. The shoes start out stiff, but quickly get a little more give. “And then your shoes just last you,” she says, until at some point, “It’s all over, it’s a rapid decline.”
And when it comes to EV batteries, two things are becoming clear. The initial drop-off is not as severe as some people had worried. And the sharp end-of-life decline is taking a long, long time to materialize.
At auto auctions, a lot of healthy batteries
Adam George is a vehicle services director at Cox Automotive, which runs used car auctions around the country. In recent years, the number of used EVs for sale has increased enormously — reflecting the sharp rise in production a few years ago.
That’s given Cox Automotive a growing pool of used EVs to evaluate before they’re re-sold.
“We were expecting battery health to be experiencing mass degradation over the first one to three years of owning a vehicle,” George says. “What we have seen, though, is that these 2, 3, 4-year-old off-lease cars that are coming back have battery health scores well upwards of 95%.”
Recurrent’s data also shows that cars from most major brands retain 95% or more of their expected range after 3 years, thanks in part to software and battery management systems that are designed to correct for the battery’s early degradation, and give drivers consistent range.
So the initial drop-off in that S curve is in the range of 5% or so, give or take. After that? Well, Cox Automotive has tested nearly 80,000 EVs, and found an average battery health of 92%.
Decade-old EVs are overwhelmingly on their original batteries
That data set is naturally skewed toward younger vehicles, because the vast majority of EVs on the road today are fairly new. There were only a million EVs sold between 2010 and 2018, and now there are more than a million sold each year.
So what about the oldest EVs, specifically?
Recurrent’s data can help answer this question. Najman, a data scientist, notes a few caveats: It’s a fairly small dataset, just because there weren’t many EVs built more than a decade ago. And some of the oldest EVs use technology that can’t connect to Recurrent’s opt-in network.
But based on their community, among EVs that are 10 years old or older, only 8.5% have ever had a battery replacement. More than 90% of them are still on their original battery.
“EV batteries are holding up phenomenally well,” Najman says.
Recurrent has also looked at EVs of any age that have more than 150,000 miles on them, which provides a closer look at the effects of that cyclical aging. There, too, the batteries outperformed expectations.
“Cars with 150,000 miles or more, and that have not had battery replacements, are getting at least 83% of their original range,” Najman says.
Now, there is one common reason why EV batteries will be replaced very early on: a defect. There have been multiple large-scale battery recalls, and any individual battery might have a flaw that requires replacement. But because all new EVs come with warranties, that kind of replacement isn’t a financial blow to owners.
“That would be something that would be synonymous with, like, your engine or a transmission going bad,” says Adam George, of Cox Automotive. “That’s what warranties are for.”
EV battery warranties typically cover at least 8 years and 100,000 miles, and automakers will replace the battery in the case of catastrophic failure, or a reduction in capacity (usually to 70% of the original or less).
A robotic arm displays the dual engine chassis of a Model S electric sedan at the Hawthorne Airport in Los Angeles on October 9, 2014.
MARK RALSTON/AFP via Getty Images/AFP
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MARK RALSTON/AFP via Getty Images/AFP
The tale of one Model S
What do all these stats look like in real life? Consider Norman Hajjar’s Model S.
Hajjar was an early adopter of electric vehicles. He kind of had to be: In 2013 he became an executive at the electric vehicle drivers’ app Plugshare.
His 2012 Model S is one of the first that Tesla ever built. When he got it, he was well aware of the question mark about battery lifespan. “There was really no way of knowing what the future held for it because there was zero track record,” Hajjar says.
In his case, the future held a battery defect: a loud noise followed by his car coming to an abrupt stop. He recalls Tesla replacing the battery — free of charge and under warranty — in 2014.
Since then, he’s spent 12 years on that second battery. He’s put around 200,000 miles on the car overall. And it’s driving great, thank you very much.
“This vehicle still is a monster,” Hajjar says, affectionately. “It is extremely fast, quick off the line.”
The vehicle was originally rated to have 265 miles of range. Now it has about 220. Do the math, and it’s at 83% of its original capacity. “The amount of degradation is pretty minor,” Hajjar says.
Hajjar has moved on to a newer vehicle for his daily driver, mostly to enjoy higher-tech features. (His newer Model Y has Tesla’s advanced driver-assistance software.) His son uses the Model S these days for his commute to college. “It’s just sort of a backup vehicle now,” Hajjar says. But he plans to hang on to it. He’s sentimental about it, he says.
Why are batteries outlasting expectations?
The engineers who developed modern EVs knew that prolonging battery life would be crucial. They designed systems to actively manage temperatures to improve battery lifespan, and software to constantly check battery health. Years have shown those efforts paid off.
But there’s another reason EV batteries have out-performed expectations. It turns out that testing batteries is harder on them than the real world. Their lifespan was underestimated.
Simona Onori’s lab at Stanford University has done research into the longevity of lithium-ion batteries, including a 2024 paper in Nature Energy showing that traditional methods for testing battery life are very stressful, and don’t match the way batteries are actually used.
In most lab tests, researchers repeatedly cycle them from a very high state of charge to a very low one.
Real-world driving is gentler, with stops and starts — each start draws a bit of the battery’s power down, while each stop gives it a little time to recharge. A driver would never slam the accelerator to the floor and keep it there until the battery is dead.
“We accelerate, we decelerate,” Onori says. “The battery will be charged, and discharged, some rest if you’re at a traffic light.”
Her lab’s findings suggest that the traditional tests for battery life were unrealistically challenging, and Onori says ongoing work with real-world data is now confirming that. When they’re actually driven, she says, EV batteries “age gracefully. Very gracefully.”
Just like humans, she notes: “When we live a life with less stress, we live longer.”
A decade plus … and counting
So how long do EV batteries last? It’s still too soon to put a precise number on it, because — as a group — the cars already on the road haven’t yet reached the end of the S-curve, the point when they will start to show massive performance declines. In other words, they’re not dead yet.
How to extend an EV battery’s life
• First, heat is the enemy. “If you live in a place like Arizona or New Mexico, we always tell people to try to park your cars in the shade,” says Liz Najman, of Recurrent. “If you have a garage with some sort of climate control, that’s a great place to park your EV.”
• Batteries also don’t like to sit around at the extreme ends of their capacity, either totally empty or full. So for daily driving, Najman recommends keeping batteries somewhere closer to the middle — driving down to 20% maybe, and charging up to 80% — and only charging to 100% before a road trip.
• Fast charging is also rough on batteries. Research from Geotab, a fleet management company, has suggested that frequent fast-charging is the biggest stressor that leads to faster-than-usual degradation. “Do some slow charging from time to time,” suggests Onori. “That might help.”
Meanwhile, battery technology keeps improving. The oldest EVs, like Hajjar’s Model S, may not be the best indicator of how long newer EVs will last. Software systems to manage batteries have gotten more sophisticated. A lot of new EVs use a different battery chemistry — lithium iron phosphate or LFP — which lasts even longer than lithium-ion batteries.
As Stephanie Valdez-Streaty, who follows EV trends for Cox Automotive, puts it: “These batteries are built to outlast the cars.”
And there’s one more wrinkle when it comes to figuring out the end of life for a normally-aging EV battery. They don’t die abruptly, like an old engine cutting out. It’s more that their range shrinks; they can only hold enough power for shorter and shorter trips. Instead of shelling out for an expensive battery replacement, some EV owners might just put up with that limitation.
Thomas McVeigh, of Ontario, Canada, drives a 2014 BMW i3. That vehicle didn’t have an impressive range even when it was new, and now it can only manage about 55 miles on a single charge in the winter. But it still looks great. It’s pleasant to drive. It saves him on gas. Maintenance is wildly cheap for a 12-year-old vehicle, and especially for a BMW; his only real cost is new tires.
He’s fine with its diminished range. And he’s not inclined to put what he estimates would be a $6,000 battery into an aging car. Instead, maybe he’ll pass it on to his kid. “Teenagers generally aren’t going for long drives,” he says.
Or maybe he’ll keep it for himself, after all. “I mean,” he says, “I love that car.”
