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A guide to your electric car battery: costs, types and lifecycle

By Celia Topping Friday 04 December 2020

electric car battery

It’s out with the old and in with the new! Following the recent government announcement that the sale of all new petrol and diesel cars will be banned from 20301, it's clear that we’re in the middle of an electric vehicle (EV) revolution! This is the biggest thing to happen to cars since Henry Ford built his Model A in 1903. Bigger – and yes, also far better for the environment. 

Are you:

  • an early adopter with your shiny new electric car charging neatly on your drive?

  • trying to figure out whether now’s the right time to make the switch?

  • still a bit lost when it comes to understanding electric vehicles?

Whichever category you fall into, it's worth understanding how EVs work – because they’ll play a big part in the future of transport.

Perhaps you already know that EVs are better for the environment and can save you money, while being smoother and quieter to drive than all the cars that have come before. But still, far too many of us don’t quite know how electric cars actually work when it comes to batteries and charging.

And there’s also ‘range anxiety’ – which means worrying about how far you can drive without charging. This article aims to calm your fears, and tell you all you need to know about the power behind the motor. You’ll be an expert in no time!

Thinking of buying an electric car? Read our article on "Things to consider when buying an electric car" by OVO's resident EV expert, owner and enthusiast, Chris Britton. 

How do electric car batteries work?

Electric vehicle batteries are a far cry from the heavy lead-acid batteries in conventional combustion engine cars. They’re actually more like the one in your mobile phone – but much bigger, more reliable and less likely to run out when you need them!

An EV car battery is made from hundreds of cells, bundled together into modules, then assembled into the battery unit. And it’s huge – being almost the length of the car. It certainly doesn’t fit snugly under the bonnet, like the batteries of old. Instead, it’s hidden away below your feet in the lower chassis.

This might sound a bit of an odd place to put such a vital bit of kit, but the battery is very well protected here. And it’s also conditioned to keep working at just the right temperature, no matter what the British weather throws at it!

The battery works in cycles of charging and discharging. While it’s plugged in, all those cells get charged up, and then the electricity's discharged when it’s out on the road. 

What kinds of batteries do electric cars use? 

Here’s the geeky tech bit. But don’t worry – we’ll keep it as jargon-free as possible:

Lithium-ion batteries

Electric vehicles use lithium-ion (Li-ion) batteries. They’re similar to the ones used in your mobile phone, but much larger and more robust. Here’s the lowdown:

  • There’s no lithium metal in the batteries, only ions

  • These ions are carried by electrolytes from the anode to the cathode2 through the separator

  • This movement (roughly speaking) creates electricity

  • Li-ion batteries have a high-energy density, which means they’re light and small, making them better for acceleration

  • They're also very stable, so can be discharged and recharged hundreds of times without degrading

  • Unlike other types of battery, EV batteries have a low self-discharge rate – which means they’re less likely to lose their charge when they’re not being used

Ok, chemistry lesson over! EV battery technology is really only in its infancy. But as time goes by, battery tech will become better – meaning cheaper, smaller, lighter, and more durable batteries in years to come. 

What is regenerative braking, and how does it help?

Essentially, braking is inefficient. It slows a car down, causing a loss of energy and momentum. That means a car has to use more energy to accelerate again. Of course, braking is an essential part of driving. We certainly don’t recommend you give that up!

When you slam on the brakes in a petrol car, all that kinetic (motion) energy is lost. But with an EV, the motor cleverly converts much of the kinetic energy and stores it in the battery, ready for when the car accelerates again. How cool is that?! 

This way, braking isn’t so wasteful, because the battery gains the energy which would otherwise be wasted.

EV battery capacity explained

electric car battery capacity

Instead of an engine, an EV has a motor. And instead of a fuel tank, an EV has a battery – which powers the motor. 

An EV’s battery capacity is measured in kilowatt-hours (kWh). For example:

  • A Tesla Model S has a 100kWh battery, which means it can drive over 400 miles on a full charge

  • A standard family EV (like a Vauxhall Corsa-e) has a 50kWh battery that can power it for 209 miles

  • A smaller runaround (like the Honda E), may only have a 35kWh battery, but it’s still capable of driving 130 miles on a single charge

Generally, the higher the kWhs, the further a car can go on one charge – just like a petrol car with a bigger fuel tank can go further before filling up. But remember, you can’t ever fully charge an EV battery to 100%, or completely empty it. It’s a clever design feature to protect the battery, keep it running efficiently, and extend its lifespan. 

Choosing an EV with an appropriate battery capacity makes financial sense. There’s no point splashing out on a Jaguar i-Pace with a 292-mile range if you’re only using it around town. And if you frequently drive long distances, buy a car with a bigger battery, or just accept you’ll have to top up more often. 

To find out more about where and how to charge your EV, read our handy guide. 

And if you're still not sure about the 3 main different charging options for your EV (slow, fast and rapid), check out our blog on the subject.

How long do electric car batteries last? 

Thanks to the hundreds of cells inside an EV’s battery, they’re able to retain their charge even after driving hundreds of thousands of miles. Nowadays, most EV batteries have a life expectancy of up to 20 years3 – which might last even longer than the car itself!

As a result, most cars come with an extended warranty of 8 years, or 100,000 miles. Good to know, right?. And as technology keeps developing, so too will the longevity of EV batteries. 

How much does it cost to replace an EV battery? 

It’s unlikely you’ll need to replace your car battery during the car’s lifetime. But before you buy one, be sure to check your warranty and make sure it covers you for any potential battery failure. 

The good news is, as with most new tech, prices will fall as technology improves. McKinsey reports that batteries fell about 80% between 2010 and 2016. And some predict prices could fall as low as £75 per kWh by 2030. Which is excellent timing for the UK government’s ban on sales of new petrol cars. 

How much is electric car battery insurance?

Unfortunately, at the moment, insurance for EVs remains slightly higher than for traditional cars. This is because:

  • The battery costs more to produce.

  • EVs tend to use more expensive and advanced lightweight materials, which are costly to replace.

  • Even after a fairly minor collision, most manufacturers insist on replacing the battery. This is due to concern that the lithium ion battery’s fuse could have been triggered and possibly catch fire. 

  • Currently, only the more expensive dealerships have the specialist technical knowledge needed to fix an EV’s electrical systems.

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The good news is, insurance prices will drop as EVs go mainstream, and the market becomes more competitive. And if you can’t get insurance through a mainstream insurer, check out some of the tailored options from specialist EV insurance companies. 

Explaining the environmental impact of electric car batteries

As you probably already know, if you charge a Battery Electric Vehicle (BEV) with renewable energy, there are no nasty carbon emissions when you drive it. And that’s true for its entire lifecycle. This means that driving a BEV instead of a petrol or diesel car can cut an estimated 2 to 3 tonnes of CO2 from your carbon footprintn per year. 

But that’s not the full story. Of course, car batteries have to be manufactured. And therein lies the biggest problem – because it’s the battery manufacture that causes more than a third of an EV’s lifecycle carbon emissions.

In fact, EVs create more emissions than regular cars during the manufacturing process. But crucially, these emissions are more than balanced out later in the EVs lifecycle5.

To find out more about the environmental impact of EVs, check out our informative guide

What happens to electric car batteries when they can no longer power a car?

So, what happens to a battery once it reaches retirement age? To throw it away would be a devastating loss of the rare materials inside it. And to resign it to landfill would also be a major environmental concern, due to issues like soil contamination. Instead, there are 2 far greener options, which mean a battery can have a new lease of life once its main job is over:

Reusing EV batteries

Once an EV battery is no longer capable of powering a car, it can be reused for energy storage in the home, workplace or electricity network.

Read more about how your battery could be reused in our useful guide. 

Recycling EV batteries

Alas, batteries can’t be reused forever. Eventually they’ll wear out. But, the rare materials they’re made from can still hold potential. There isn’t a perfect recycling process for these yet – but read our guide to find out what’s being developed

Best electric car battery manufacturers 

As you’d expect, there are many EV battery manufacturers, each competing for market share. Most of them are based in Asia. Here are our top 3 picks:

  • Tesla is probably the most well-known. 

  • LG Chem is also a major player, supplying batteries to Volvo, Renault, Ford and Chevrolet. They’ve recently also signed a contract with Tesla.

  • BYD is the biggest EV manufacturer in China – and they’re now actually selling more EVs than fossil fuel vehicles!

Electric car battery charging

electric vehicle charging

Plugging in a car: it’s an unfamiliar concept, and it may still seem a little strange. But as EVs become more mainstream, the sight of a row of cars plugged into chargers in a car park, by the kerb, or on someone’s drive, will soon become the norm. Read on to find out more about how to charge an EV.

How far can you go on one charge? 

‘Range anxiety’ is a real thing. And it’s not surprising. No one wants to be stranded by the roadside because their car’s run out of battery. How inconvenient! 

As explained above, car batteries come in different sizes. A typical 40kWh battery could power a car for around 150 miles – whereas Tesla’s biggest 100kWh battery could go for 400 miles or more on a single charge. 

Just as a petrol car has a gauge to let you know exactly how much petrol you have left, an EV has a display indicating how full your battery is. And just like it’s good practice to top up with petrol when you hit the ¼ full mark, it’s recommended to keep your battery charge above 30%, so you can reach the next charging station before it runs flat. 

How do you recharge an electric car battery? 

It’s simple – just open the plug socket on the side or front of the car and plug it in! There are various kinds of car charger, all offering different charging speeds – from a slow 3kWh to an ultra-rapid 150kWh. 

You can access chargers in various urban settings – from motorway services, car parks and workplaces to your very own home. And it’s easy to pay – either via your home energy plan, by contactless payment, or with a subscription. 

To find out more about charging, see our complete guide to EV charging

What is Vehicle-to-Grid technology?

Innovations in EV technology are coming thick and fast. Two-way Vehicle-to-Grid (V2G) technology is one such invention. It allows energy stored in EVs to be fed back into the national electricity network (or 'grid') to help supply energy during peak demand. This means you’ll soon be able to use your car’s stored energy to actually make money! 

Read more about the ingenious V2G in our informative guide. 

How safe are electric car batteries?

You’ve probably been driving around for years with highly flammable liquids sloshing around in your tank, without even thinking about it. In fact, ithium-ion batteries pose far less risk of catching fire or exploding than petrol.

EV batteries do, of course, get warm during use – but smart management systems stop them overheating. Safety is a number one concern for car manufacturers, and they go to great lengths to ensure the EV batteries they install are safe. 

Top tips to prolong your EV’s battery life

Your EV’s battery will wear out gradually over time – but there are ways to keep it in good condition and extend its life. Here’s a list to keep in mind if you want to make the most of your battery:

  • Watch your speed – just like petrol cars, burning rubber will also burn through your battery. The Department of Energy says you’ll use 14% less energy by lowering your speed by 10 mph, and recommends staying under 60 mph wherever possible.

  • Don’t always be in a hurry to charge – although it’s handy at times, repeated rapid charging is not very good for your battery – so try to avoid doing this too much. 

  • Drive smoothly – don’t be tempted to show off as you screech away from that green light! Your battery won’t like it, even if your passenger might!

  • Remember the 20% to 80% rule – charging to full capacity, and allowing your battery to run completely flat isn’t a good idea. If you’re going away for a few days, set your charger to 50%.

  • Pump it up – keep your tyres properly inflated to get the best from your battery. 

  • Blowing hot and cold – using your battery for AC or heating is a quick way to drain its power. Instead, pre-warm or cool your car while it’s still plugged in, to save on battery power.

Want to find out more about electric cars? Check out even more of our EV articles

Thinking of buying an EV? We can help you charge your electric car everywhere, for less. Our EV Everywhere tariff is designed specially for owners of electric (and plugin hybrid) cars. It comes with fixed energy prices for two years, 100% renewable energy and free membership of Polar Plus, the UK's biggest EV charging network.

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Sources and references: 

1 https://www.ft.com/content/5e9af60b-774b-4a72-8d06-d34b5192ffb4

2 https://www.energy.gov/eere/articles/how-does-lithium-ion-battery

3 https://insideevs.com/news/351314/nissan-leaf-battery-longevity/

4 https://www.carbonbrief.org/factcheck-how-electric-vehicles-help-to-tackle-climate-change

https://www.thisismoney.co.uk/money/cars/article-6963195/Electric-cars-SMALLER-carbon-footprints-lifetime-says-VW.html