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Question of the week: How long do EV batteries last?

David Ross, Editor
Fri, 08 Nov 2024

Dear Honest John,

"What is the typical battery life for electric cars? Does battery degradation happen after a certain mileage, or years? Can batteries be replaced, and at what cost?"

- JS

Dear JS,

There is no definitive answer to this, in the same way that there are no guarantees on how long the engine in a conventional car will last.

Most manufacturers of EVs offer a battery warranty of between eight and ten years or 100,000 miles, whichever comes first, which is broadly in line with the warranties for petrol and diesel cars.

Just as with conventional engines, looking after your electric car will go a long way to extended its lifespan - there are examples of EVs on their original batteries with over 200,000 miles and more, with a reasonable battery percentage remaining.

But you will also find older electric cars where the battery has depleted so much that the range is less than 40 miles.

Like the battery in your mobile phone or laptop, EV batteries lose efficiency the more charge and discharge cycles they go through. Even so, the accepted standard is that an EV battery will retain at least 70% of its capacity after 200,000 miles.

Batteries do also degrade with age, but this is around 1%-3% per year, so this is less of an issue than how the battery is used.

Avoiding draining the battery below 20%, not charging it to above 80% and limiting the use of rapid chargers should in theory, all help increase the battery life of your EV. It is also important to remember that battery technology is continually evolving and these performance measures will continue to improve with time.

Broadly speaking, battery life is unlikely to be an issue for new car buyers unless they plan to keep their cars for 10 years or more. For used electric car buyers, more caution is required - checking the battery's current state of health compared to when new will give a good guide to the lifespan remaining.

Replacement batteries are available for some models, but the cost can be anything from £3000 to £15,000 or more depending on the capacity of the battery and the vehicle.  

Ask HJ

What is the lifespan of hybrid batteries?

While there has been considerable research on the life of full EV batteries, I wondered if you have any advice on battery life in hybrid cars. I am looking to purchase a used hybrid car, but I wonder if there is an age or mileage beyond which the batteries may have started to degrade? Clearly, this would not stop the vehicle from running, but I assume the fuel economy benefits will reduce over time? Any advice welcome.
All batteries will degrade from the first day of use, but with hybrid vehicles the impact is not as significant as the batteries are not in use all of the time and are only partly responsible for providing drive to the wheels. Although mileage plays a part in how much batteries have degraded it also depends on how the vehicle has been driven. Urban driving will mean more use of the batteries compared to motorway speeds, so theoretically a car that spends more time on the motorway will have a longer battery life. A degraded battery will be able to operate less of the time, so fuel economy will be reduced as the battery ages. However, cars like the Toyota Prius have been around a long time and many examples have gone past 200,000 miles, so a hybrid is capable of big mileages.
Answered by David Ross
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