COP26: Should you be worried about diminishing electric car battery life?

It's 'Transport' day at COP26, which means world leaders are debating a number of ways that we can remove carbon from transportation. While long-haul flights and improved public transport options are key to the discussion, there's understandably an increased interest in electric vehicles. One of the key concerns around them is their reliance on battery power and the life of those batteries.

Driving range and access to charging facilities are key considerations when buying an electric car, but there is also much speculation surrounding battery life and degradation. We asked 2,110 EV drivers about their ownership experience over the past 12 months, including just how well their battery is holding its charge.

The case for switching to an electric car is growing stronger all the time. Prices, charging times and driving range are steadily improving, while the benefit of zero-tax (at least for now), potential for very cheap running costs and no tailpipe-emissions further bolster their appeal for those looking to shrink both their costs and carbon footprint.

However, anyone who's suffered with an ageing laptop or smartphone will know about the weaknesses of lithium-ion battery life. With a ban on internal combustion cars on the horizon (2030 for petrol and diesel, 2035 for hybrids), should new car buyers expect a much shorter usable life from battery powered EVs compared to what we're used to?

Keep reading to find out what our latest survey results tell us about the longevity of EV batteries. Or to find out which EVs aced our road and lab tests: see our pick of the best electric cars for 2021.

Live more sustainably - get our free Sustainability newsletter to make changes for you and the planet

Does an EV battery lose range as it ages?

This is the second year running we've asked EV owners (across all available car class types), and again the results show that as an electric car ages there is a slight but definite reduction in the average battery life available.

While owners of new electric cars can rely on their batteries, with those up to two years old having around 98% of their original range available on average, drivers of older models (dating back to 2014) report a steady decline in usable battery life, with the oldest models capable of 91% of range from new.

The electric cars we've run through our independent lab tests have an average range of 160 miles. That should mean that over six years, based on the feedback we've received, you can expect that maximum range to fall to around 146 miles.

A 9% reduction in usable range over seven years probably won't be enough to dissuade you from buying an EV, especially if you're leasing, but it's a factor that will affect longer-term owners and second-hand buyers. We'll continue to gather data on EV battery life in future surveys.

Find out how to keep your battery charged, both at home and on the road, in our guide to electric car charging.

Battery replacements on the rise

We reported last year that only around 3% of electric car owners have suffered the inconvenience of having a faulty battery pack replaced entirely. The latest figures suggest that this is rising as more drivers make the switch. This year, of the 2,184 EVs we heard about, 163 required a full battery pack replacement.

Premium brands are just as susceptible to having to provide expensive replacement batteries. Around 7% of Tesla owners (Model S, Model X and Model 3) needed a new battery pack, which is close to the average (8%) across all brands that we hold data for. Meanwhile just 3% of Renaults - across the Zoe (2019), Zoe (2013-19) and Fluence - suffered the same problem.

For tips on living a more eco-friendly life while still getting the products you need at good value, head to the latest Which? sustainability advice.

Data from 2021 Which? Car survey: April 2021 to June 2021 covered the ownership experience of 56,853 cars - of which 2,184 were electric models.