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A lifespan of 300,000 miles would be a conservative estimate for modern EV batteries, an expert has said.
Business Car spoke to Dr Euan McTurk, of Plug Life Consulting, following an appeal by the Vehicle Remarketing Association (VRA) for standard battery health checks to be introduced for used EVs.
VRA chair Philip Nothard said the measure was needed because of consumer concerns over battery life, even though the association knew these were largely unfounded.
Just how unfounded was explained to us by McTurk, a consultant battery electrochemist, who said that degradation rates were generally "incredibly low".
He suggested that many people were basing estimates of a three-to-five year lifespan for EV batteries on what they had experience from smartphones or laptops, but that this ignored crucial differences.
McTurk explained that compared with a smartphone battery, a modern EV battery had about ten times less cobalt percentage-wise, operated at cooler temperatures, had a liquid-based thermal management system, and had far more conservative voltage limits - all of which contributed to improving lifespan.
He said: "Even the eight-year warranty that EV manufacturers give for their batteries these days is very conservative, and there are companies that are offering extended warranties for EV batteries because, quite frankly, the risk is that low.
"Realistically you are looking at hundreds upon hundreds of thousands of miles of lifespan out of an EV battery. Especially a more modern one - every iteration coming out is even better.
"But conservatively, for most EVs out there you'd be disappointed if you got less than 300,000 miles out of the original battery, and plenty have done considerably more than that."
McTurk added that some people may have been put off by an example of a used Nissan Leaf shown on the TV show Top Gear with a much-reduced range, and explained that early Leafs were an outlier.
He said: "The Nissan Leaf doesn't have a thermal management system, and the original chemistry used in the very first Leafs had poor heat resistance, and as a result those batteries did degrade particularly quickly.
"But if you look at the Sunderland-built Leaf - it still doesn't have thermal management, but it has much better cell chemistry, and those are still typically going strong."
Despite generally very low rates of EV battery degradation, McTurk said he could see a use for battery health certificates, but that the main benefit of these would not be seen for many years.
He said: "It could be that a battery has got a reduced range versus when that vehicle was new, but that range is actually more than enough for some customers.
"If it's a 300-mile-range car that's now down to 70% - which would trigger a warranty replacement in the first eight years - that's still just over 200 miles per charge, so that's plenty for a lot of people. It could be the very highest mileage drivers would say they need closer to 300, but other drivers would find 210 miles entirely reasonable and could use that as a haggling point to get a cheaper car, because yes, it's got less range than it did have, but it's perfect for them.
"That's where battery health certificates come in very useful. We are talking years down the line from now, but we might as well get that foundation in place today so that we can say 'this is the real-world range you can expect from this particular EV'.
"If someone was buying [an EV] under the thought that it would do a solid 240-250 miles, which it did when it was new, and it's now sort of 220-ish, that kind of certificate would be quite useful for them, so they know what they can expect, and it would be less of a gamble for them.
"But what we will find for many years now, even for most earlier EVs, is it's generally going to be good news that certificate is giving you. It's going to be many years down the line before we see significant degradation to the point you'd want to consider replacing that battery or retiring that vehicle."
When asked if there were differences between EV battery types that buyers should be aware of, McTurk said that while degradation rates generally were very low, new lithium iron phosphate technology had numerous advantages.
He said: "One [advantage] is it doesn't have any cobalt or nickel, so it's comparatively ethical. It's also comparatively safe - it's very difficult to get them to catch fire. And you can routinely charge them to 100% without any issues.
"You can charge them up more times before they fail to a point they are no longer usable in a car.
"If I was a savvy buyer I'd be going for a lithium iron phosphate one, partly because it's ethical, partly because it's a very long-lasting battery, partly because it's even safer. The only thing it doesn't like as much is cold weather; you lose a little bit more range in winter."
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