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Electric car battery life: how to preserve your battery

Here's how to preserve the battery in your electric car as much as possible, and how much a replacement battery will cost in the unlikely event you need one

Ford Mustang MACH-E

As well as the cost of buying one and how far it'll go on a full charge, battery life is one of the major concerns for those interested in getting an electric car. This isn't surprising, as most use lithium-ion batteries – the same as the ones in your laptop or smartphone. And as we're all too aware, they tend to lose some of their capacity over the course of their life.

However, while the fundamentals of your phone battery and the one in your electric car are the same, there are significant differences in how they're charged and discharged. Unlike your phone's cells, most electric-car batteries have a built-in buffer, which means you can never really drain them to a true 0% or charge them to a true 100%. The continual 0-100% charging cycle is what's most damaging to batteries over a relatively short timespan, hence car manufacturers working to mitigate this.

Battery degradation is less crucial in a phone, as most people replace theirs every two or three years. Fortunately, most carmakers provide a standard eight-year or 100,000-mile battery warranty and will cover a certain amount of battery degradation during this time. So new and used electric-car buyers can feel confident.

First-generation electric cars like the Nissan Leaf have been around for over 10 years now and, according to previous Driver Power owner satisfaction surveys, it's one of the most reliable used cars in the UK; more than 90% of owners have experienced no problems at all with their cars. And according to aftermarket warranty supplier WarrantyWise, both the Leaf and its first-generation counterpart the BMW i3 had lower repair rates than internal-combustion equivalents covered by its policies.

However, there are steps you can take to make sure your electric-car battery stays in good health and prolong its lifespan even further.

Tesla Model S

How to prolong your electric car battery’s life

1. Don’t overcharge it: constantly topping up your electric car to keep it fully charged can actually damage it. Laptops, for example, lose battery capacity if they're plugged in all the time. It's better to let the capacity run down to 10 or 20%, then recharge to around 80%.

2. While electric-car batteries have a built-in thermal management system to keep them cool, it’s still worth seeking out a shady spot on a hot day, or even a garage or car port if you plan to charge at home.

3. It’s also advisable to avoid immediately charging your electric car following a particularly spirited drive. Give the batteries a chance to cool down first.

4. Limit your use of rapid chargers. Obviously, there are times when you need a top up in a hurry, and the fact they can give you a quick boost of up to 80% in a short space of time will be invaluable to higher-mileage drivers. But don’t rely solely on rapids to keep your car topped up, as they’re not good for the batteries in the long run. Slow charge whenever you can and especially if it's cold outside.

5. Don't park your car uncovered for long periods of time in very hot conditions.

Volvo battery

How much does a replacement electric car battery cost?

It's extremely unlikely you'll need to do this, but to give an idea of costs, and using the first-generation Nissan Leaf as an example, getting a main dealer to replace a 24kWh battery pack would cost around £12,500, whereas a 30kWh pack would cost roughly £14,300.

These prices are ballpark figures as there will be slight variations from car to car depending on age and condition of the old battery. It's a lot cheaper to get a third party to fit a good-condition used battery. Replacing a 24kWh battery this way would cost around £5,500 – although that's highly dependent on how much a secondhand  pack can be sourced for.

However, unless your car's battery has been particularly badly treated, you shouldn’t need a new battery for many years, if it all. If your car is less than eight years old, a particularly degraded battery should be covered under warranty.

It may also be that a degraded battery doesn't need to be dumped entirely; it could just be a few faulty cells that need to be swapped out. There are independent electric-car specialist service centres that can carry this job out, for about £500, so it could be worth looking into.

Nissan Leaf

Should I be worried about battery degradation?

Using data from GPS fleet tracking firm Geotab, Select Car Leasing analysed 64 electric cars built between 2012 and 2019 to see how battery degradation affects electric cars, and whether or not newer models are more resistant to the effect. 

The Nissan Leaf was picked as an example, as it was one of the first modern mass-produced electric cars to be sold in the UK. Select Car Leasing's study found those built between 2011 and 2013 will today have around 80% of their battery capacity left.

Earlier modern electric cars are particularly prone to battery degradation, the study claims: a 2013 Leaf lost 3% of its capacity after one year, while a 2015 model lost 6% the first year, while a newer, more advanced 2019 model lost just 1%.

According to the study, the electric (and plug-in hybrid) cars with the lowest percentage of battery degradation included the Audi A3 e-tron (0.3% year-one degradation), Tesla Model 3 (0.6%) and Tesla Model X (0.7%), along with other favourites like the BMW i3 (0.9%) and Tesla Model S (1.1%). 

In contrast, at the opposite end of the study's results, some popular models returned some less impressive battery degradation results. The Mitsubishi Outlander PHEV was the worst hit, with 4.1% of its battery capacity lost in the first year. The Kia Niro PHEV lost 3.5%, the Volkswagen e-Golf 1.7% and the Kia Soul EV 1.6%. The popular Volkswagen Golf GTE hybrid didn't fare too well, either, with 1.7% of its battery capacity lost in the first year.

Overall, the study shows that newer electric cars tend to be less prone to degradation – so it pays to choose as new an electric car as you can afford when buying a used one.

Hyundai Ioniq

What should I do if I’m buying a used electric car?

The most important thing is to check how much of the manufacturer’s original battery warranty is left. It's worth getting the car’s battery status checked at an independent specialist, too. The good news is that – as mentioned above – in some cases it’s possible to change the individual cells rather than the whole pack, which is substantially cheaper.

And if the car's manufacturer battery warranty has expired, you can continue to guard against having to shell out for a battery replacement or refurbishment by purchasing an extended warranty from a third-party supplier. MotorEasy launched just such a warranty in November 2020.

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