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A large, real-world study of electric vehicles sheds light on a question that anyone shopping for a used EV should be asking: How long do EV batteries last, exactly?

Replacing an EV battery can cost anywhere from US$5,000 to US$22,000. That’s not a repair bill anyone wants to see, especially on an out-of-warranty used car.

The good news for those in the market for an older EV is that, for the most part, batteries are reliable and long-lasting, according to a March study by Seattle-based battery analysis company Recurrent Motors Inc.

The majority of EVs that have been driven more than 160,000 kilometres in Recurrent’s study still have at least 90 per cent of their original range left. That said, the study’s author, Liz Najman, researcher and marketing manager at Recurrent, cautioned that individual vehicles do vary and that Recurrent’s data are always evolving.

“I was surprised how well batteries are holding up, and how relatively infrequently batteries are being replaced. That was a shock,” Najman said in an interview with The Globe and Mail.

The study, published last month, gathered real-world data from 15,000 EVs of various makes and models on the road in the United States. Recurrent takes several battery readings daily, including charging activity, EV battery level and estimated range, by hooking into the car’s connectivity system. The company, which says it hopes to encourage EV adoption by making such information more readily available, uses odometer readings as a proxy for vehicle age.

Age matters because, just like the batteries in your cellphone or laptop, EV batteries degrade with use and time. Where your cellphone will slowly stop lasting through an entire day without a recharge, your electric car will lose driving range, reducing the distance it can cover between charges.

Unfortunately, how an EV’s battery will hold up over time is largely an unknown, simply because most EVs aren’t that old. Almost 30 per cent of EVs on the road today in the United States were sold in 2022, and the majority are less than six years old, according to Recurrent.

Looking back at how EVs are holding up thus far bodes well for the future. The study tracked both battery replacement rates – how often a car’s battery fails entirely and needs to be replaced – as well as how driving range declines as batteries age.

When it comes to replacement, among the 15,000 cars in the study, 1.5 per cent or about 225 cars have had their batteries replaced outside of official recalls.

“Even for somebody in the [EV] space, seeing that 10-year-old EVs are still having a battery replacement rate – that we know about – of less than 10 per cent is really impressive,” Najman said.

The standard EV battery warranty is eight years or 160,000 kilometres, with a certain percentage of original capacity remaining, depending on the manufacturer. So at 10 years, if anything goes wrong, in most cases the driver will be on the hook for the cost of a replacement battery.

In the decade since those early EVs hit the road, however, lithium-ion battery technology and control systems have improved. Not only that, but new types of batteries – like the lithium iron phosphate (LFP) batteries in certain new Tesla models – don’t degrade as much as lithium ion. (Although, in the case of LFP, they’re not as energy dense either.)

When it comes to range, there’s quite a bit of variation between makes and models, and even within models.

For example, Recurrent found Tesla’s Model S with the 100-kilowatt-hour battery pack loses roughly 120 kilometres of range, on average, after 160,000 kilometres. Model S’s with the smaller 70- and 85-kilowatt-hour battery packs lost almost no driving range after covering the same distance.

Early BMW i3s – both the 2014 and 2017 models – have, on average, hit 160,000 kilometres with about 80 per cent of their original battery capacity remaining, according to Recurrent findings.

The Hyundai Ioniq 5, which only arrived in late 2021, is so far holding up well. After losing about 25 kilometres of range over the first 32,000 kilometres, there was almost no further degradation out to 130,000 kilometres.

“For the EVs produced from roughly 2018 or 2019 on, I think we’re looking at 15 to 20 years before they see significant [battery] degradation, beyond a usable capacity,” Najman said.

Recurrent’s study broadly aligns with previous research, including a 2020 report by Canadian transportation technology firm Geotab. That study found battery degradation was modest, with an average capacity loss of 2.3 per cent a year.

“I don’t think I’m alone in the assumption that modern EV batteries should outlast the cars themselves,” Najman said.

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