Electric car battery guide

The defining feature of an electric car is its ability to run on batteries. Find out more about your car's batteries, including where to charge them and how to replace them.

gocompare author
Updated 13 July 2021  | 3 min read

Electric car batteries explained

Sales of electric cars in the UK have increased dramatically over the last decade and it’s expected that by 2050 eight out of 10 cars sold will be powered by electricity.

So, if you’re considering buying an electric car it’s a good idea to find out more about electric car batteries, how they work and what their reliability and lifespan might be to help you make your decision.

How do electric car batteries work?

To power their electric motor electric vehicles (EVs) need a high voltage, which is supplied by a battery pack in the car. The batteries in the EV are used to power the electric motor which is used to turn the wheels when you drive.

Most electric car batteries are made from lithium-ion cells and work in the same way batteries do in your mobile phone or laptop, but with a much longer lifespan.

As the energy in your electric car’s battery runs down you’ll need to charge it, just like you need to refill your car’s fuel tank when it gets low.

How do you charge an electric battery?

Charging your electric car’s battery is straightforward - just plug your car into a charging point. Electric cars come with their own charging cable, which stores easily in your boot, and most use a Type 2 charging cable which allows you to use the vast majority of public chargers.

Some charge points are tethered, which means they have a cable already attached. You use these just as you would a petrol pump and plug the end into your car’s connection point - which can be located at the front or rear of the car depending on its make or model.

If your car is charging properly you should see a light flashing next to the charge connection on your car that’s typically green or blue, depending on the EV. And don’t worry, it’s not possible to drive off when the car is plugged in - electric cars won’t let you do that.

Where can you charge your electric car?

The cheapest and most convenient way to charge your car is at home, where you can either plug it into a standard UK three-pin socket or you can have a home fast-charging point installed.

Some businesses offer free EV charge points as a staff perk, whereas others may charge or set time limits for you to use them. If there aren’t charging facilities at your workplace, the government’s Workplace Charging Scheme can pay up to 75% towards the cost of buying and installing the EV charge points at work.

Public charging points will cost more than recharging your car at home. But some public chargers are free and you can find these at places like supermarkets, retail parks and public car parks. However, free charge points often come with restrictions, such as time limits or a minimum spend in-store, so it’s best to check.

Alternatively, you can charge your car at most filling stations and service stations, where you pay to use fast and rapid chargers. To use these charging points, you’ll usually be asked to pay either via a special card, with a contactless debit or credit card, or through a payment app on your phone.

When should you charge your EV battery?

Many EV owners charge their cars at home overnight for convenience, but be aware that charging your car daily or nightly could shorten the lifespan of your battery.

To keep your battery in optimum condition only charge it up to 80% capacity, don’t let it drop below 50% too often and try to always keep it above 20% if you can.

On most EVs and chargers you can change the settings to limit the charge to 80% and avoid topping up more than necessary. You’re likely to need a full battery charge for long journeys, but only powering it to 100% when you really need to will help your battery to last longer.

However, you should always follow the battery charging recommendations found in your car’s user manual, as these will vary between makes and models.

How long does it take to charge an electric car battery?

There are generally three speeds that you can charge an EV, and this will depend on your car and where you’re charging it:

  1. Slow - The slowest rate is typically when you charge your car overnight at home using a three-pin plug charger. These chargers normally run at around 3kW and can take up to 12 hours to charge a full battery.
  2. Fast - This can be done at home if you have a fast-charging point installed. Known as wallboxes, these units typically give you a charge between 7kW and 22kW, but most home power supplies can only manage 7kW. The government’s Electric Vehicle Homecharge Scheme can provide homeowners with up to £350 towards buying and fitting a wallbox.

    Most public EV charging points are fast chargers and many are untethered, which means you need to use your car’s cable to plug in with. These tend to charge three times faster than using a domestic three-pin charger and typically take three to four hours to charge your EV.
  3. Rapid - The fastest chargers available are rapid or ultra charge points which have a power output of 43kW or more. These can be found at most motorway services stations and can charge your battery up to 80% in less than an hour.

What’s the difference between an AC and DC battery charge?

There are two types of ‘fuel’ for charging electric cars: Alternating Current (AC) and Direct Current (DC) power.

Most charging points use AC power which the car then converts to DC, this slows the charging process down so batteries take longer to charge. Generally, your home electricity supply is AC, which is why home charge points have a longer charge time.

Rapid charge points, like those found in petrol stations, are either AC units that can provide up to 43kW or DC chargers which supply a DC current directly to the car and can charge up to 50kW.

It’s also possible to find ultra-rapid charge points - these are DC only and can charge more than 100kW for those cars capable of charging at this speed and capacity.

How long do batteries last between charges?

This all depends on how often you use the car, the speed that you drive and the number of miles you travel. The frequency you’ll need to recharge also depends on your car battery size and the power rating of the charger.

The ‘Real-world range’ is what EV experts call the amount of miles you can realistically get out of your electric car. Your range on a journey can be affected by a number of factors including:

  • The weather
  • Driving uphill
  • Use of air-con and heating
  • The weight you’re carrying inside the car
  • How old your battery is

The battery’s range can also be reduced due to extreme hot and cold weather.

What happens when an electric car’s battery runs out?

Different EV makers provide different warranties, but typically most batteries come with an extended warranty of eight years. In fact, many EV batteries are still working beyond the 150,000-mile mark and some still have 90% charging capacity after six years.

Most EV batteries have a lifespan of 15 to 20 years and as technology evolves this is likely to stretch even further. To preserve your battery it’s best to keep it well maintained and avoid rapid-charging too often, which degrades the battery’s performance over time.

When an EV battery stops taking charge, this is known as 'bricking'. It’s rare that your battery will get to this stage, instead what tends to happen over time is that your EV charge lasts for less and less time, just as with an ageing mobile phone.

You can lease your car battery, which typically makes the car purchase more affordable. With leasing, you pay a monthly fee and if your battery becomes faulty or its performance drops below a certain level, it will be replaced or repaired free of charge.

If you’ve bought your battery and it's out of warranty, you’ll need to buy a new or refurbished one, and the cost will depend on the make and model of your car and its battery size and type.

How much does it cost to replace an electric car battery?

EV batteries are expected to last up to at least 100,000 miles, but if you need to buy a replacement a new battery pack can cost several thousand pounds - but a refurbished battery pack will be cheaper.

Are electric car batteries eco-friendly?

There have been a number of studies that suggest that while an EV is more expensive to make, it’s better for the environment across its life cycle than a petrol or diesel car. For example, electric cars get twice as many miles out of the same amount of energy as the most efficient petrol engines.

And when EV batteries reach the end of their life or need to be replaced, they can still have a use in your home by being used as an energy storage system if you have a renewable energy source like solar panels.

EV batteries can also be recycled and there are a growing number of ways car manufacturers are doing this and looking at how to extract and reuse the minerals and materials found inside them.