How long do electric car batteries last for?

Battery life is one of the biggest worries potential buyers have when considering an electric car. Along with range – and the fear of running out of power mid-journey, known as range anxiety – the way an electric car’s battery might degrade over time is considered a big barrier to EV ownership.

Like any battery, including the one in your mobile phone or laptop, the batteries in electric cars will lose some of their capacity over extended use. Below, we’ve explained why this happens and offered advice on how you can keep your electric car battery in top condition for longer.

Why does an electric car battery lose charge?

Almost all the batteries in electric cars are of the lithium ion variety. These batteries undergo ‘cycles’ of discharge (when you’re driving your car) and charge (when you plug your car in), and over time those cycles take a toll in terms of how much charge the battery can hold – and therefore, how far your electric car can travel before needing to be recharged.

How can I care for my car’s battery?

As counter-intuitive as it might sound, keeping your electric car fully charged can actually damage its battery, because of the heat generated during recharging. That’s why some electric cars can stop charging when they reach capacity, while others – such as the Tesla Model S luxury saloon – allow you to charge the car to a certain percentage before stopping, helping to preserve the battery.

Overcharging can also cause chemical changes inside the battery itself, which again could negatively affect how efficiently it can store energy.

Equally, discharging an electric car battery to empty isn’t a good idea. Most lithium-ion batteries perform at their best when they’re at between 50% and 80% of capacity. Charging the last 20% of a battery also takes longer than the first 80%, and that’s why when you’re reading about rapid charging of the kind you might do at a motorway service station, you’ll regularly see figures quoting how fast it takes to charge an electric car to 80% of capacity.

Another factor is temperature. Extreme cold or heat can negatively affect your car’s battery and therefore the range you can travel. In a test of the Nissan Leaf in cold conditions, for example, we managed 108 miles – substantially less than in warmer temperatures.

Electric car battery warranties

Car makers are well aware that potential buyers are concerned about the longevity of their car’s batteries, and many offer warranties tailored for EV owners. On the Leaf, for example, Nissan offers a warranty covering the battery and electric motor for up to five years or 60,000 miles.

Elsewhere, Renault’s warranty covers the Zoe electric hatchback for up to 100,000 miles or three years, while Tesla offers an eight-year warranty on the Model S that’s not subject to any mileage and can be transferred between owners.

Electric car reliability

According to the latest results from our Reliability Survey, the Nissan Leaf is the most reliable electric car, with a score of 99.7% – with the few complaints we received being about the car’s bodywork, rather than its battery. At the other end of the scale is the Tesla Model S, with a score of 50.9%. Most of those faults were to do with its electrical systems and bodywork, however; just 4% of the complaints we received related to its battery.

It’s also worth noting that there are cases where an electric car battery has long since surpassed expectations. In 2015, for example, Nissan reported the case of a Leaf that was bought in 2013 to be used as a taxi around Cornwall. The car had covered more than 100,000 miles without losing any of its battery life.

Next: electric car jargon explained >

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