The complete guide to electric car batteries

With electric cars growing in popularity in Northern Ireland, we’re all having to learn about cars that are a bit different from the petrol or diesel vehicles that we’re used to. One of the key differences is the battery, which is not the same in electric cars as in conventional cars. In this article, we’ll give you the complete guide to electric car batteries, including how EV batteries work, their lifespan and replacing EV batteries. 

Electric car batteries explained  

What are electric car batteries made of?  

There are various different types of EV batteries. Each battery type is made using different materials. The two most common EV battery types are lithium-ion batteries and nickel-metal hydride. Let’s look at each of those in more detail. 

Lithium-ion Batteries - Most electric vehicles currently use lithium-ion batteries. These are similar to the rechargeable batteries used in our phones, tablets and other electronic devices. Each EV battery is made up of lithium-ion cells. Lithium-ion batteries are made of lithium, carbon, base metals such as aluminium, copper and iron, and precious metals like cobalt, nickel and manganese. The main technical components of a lithium-ion battery are the anode, cathode, separator, electrolyte, and lithium-ions.  

Nickel-Metal Hydride Batteries - Hybrid cars sometimes use nickel-metal hydride batteries rather than lithium-ion. Nickel-metal hydride batteries are significantly cheaper but typically don’t store as much energy or recharge as quickly. They are usually made using a mixture of rare-earth metals, nickel, cobalt, manganese or aluminium, and potassium hydroxide. The main technical components of nickel-metal hydrogen batteries are the anode, cathode, electrolyte, separator and casing. 

How do electric car batteries work? 

Electric car batteries work in a very similar way to your phone battery. When you plug in an EV battery to charge, the electricity causes chemical changes so that the energy is stored in the battery.  

Just as the charge in your phone will give you a period of time to use your phone without it being charged, electric car batteries give you a ‘range’ that you can drive without needing to charge. As you drive, the chemical changes in the EV battery are reversed to create the electricity to power your car. 

Find out how electric car batteries work within an EV in our complete guide to How Electric Cars Work. 

Electric car battery capacity 

Electric car battery capacity is a measure of how much charge a battery can hold. EV battery capacity is measured in kilowatt-hours (kWh). The average EV battery capacity is 40 kWh, but some electric cars have a capacity of 100 kWh. Battery capacity usually depends on the size and intended use of the EV. A Mini Electric has a 32.6 kW battery capacity, giving it a range of about 110 miles, while a Tesla Model 3 has a 60 kWh battery capacity, which gives it an estimated range of 250 miles. 
 
EV battery capacity is important because the bigger a battery’s capacity, the greater the vehicle’s range will be. Cars with a larger battery capacity can travel further between charges, so you need to charge them less often. Battery capacity is not an important factor in petrol and diesel cars. In fact, a closer equivalent to EV battery capacity is fuel tank capacity.

Lifespan of an electric car battery  

How long do electric batteries last? 

Most electric car batteries come with a guarantee for up to 100,000 miles or eight years. A typical lithium-ion battery should last for up to 10 years, while some have been known to last for 20 years.  

What is EV battery degradation? 

EV battery degradation is the gradual reduction in battery capacity, range, power and efficiency over time. It’s similar to the way the performance of your phone battery slows the more it’s been used. Although the ageing process takes a lot longer with an EV battery than a phone battery, how the battery is charged can increase the rate of degradation. 

How to extend EV battery life 

There are several ways you can slow down battery degradation to extend the lifespan of your EV battery. Extending your EV battery life will help you to enjoy better performance from your EV for longer and without needing to replace the battery. Here are some of the things you can do to extend EV battery life:  

Avoid exposure to extreme temperatures - Keep your EV stored safely in a garage when it's very hot or cold outdoors. 

Resist the temptation to overcharge your EV battery - Only charge when you need to and avoid repeatedly charging your battery to 100%. 

Don’t let your EV battery run flat - Avoid running your EV battery down to 0% and always try to keep it above 20% if possible. 

Take your foot off the EV accelerator - Driving at slower speeds will increase your range, reduce how often you need to charge and extend your EV battery life. 

Only use rapid EV chargers when necessary - Try not to use high-voltage DC charging unless absolutely essential because slower charging creates a longer battery life. 

Electric car battery replacement  

How much does an electric battery cost to replace? 

Electric car batteries are expected to last at least 10 years, and often a lot longer. For that reason, it’s unlikely you would ever need to replace your EV battery. But if you’ve seen a significant drop in your driving range, it could be a sign that the battery needs to be replaced. 

EV battery replacement costs in Northern Ireland and the UK are currently estimated at £87 per kWh. That would mean a cost of £3,480 to replace the battery on the average 40 kWh electric car. 
 
Fortunately, EV batteries usually come with a warranty for up to 100,000 miles. Some car insurance policies also cover the replacement of a faulty EV battery outside of the warranty period. 

Can EV lithium batteries be repaired? 

In some cases, EV batteries can be repaired rather than needing to be replaced. Repairs are usually possible for minor issues, including damaged connectors or fuses. Similarly, if the battery has a faulty cell, it may be possible to replace the cell rather than the entire battery.  

There are a couple of ways old EV batteries can be responsibly and sustainably dispose of at specialist battery recycling facilities. These are: 

Second life - EV batteries that no longer power a vehicle effectively can be turned it into an energy storage system. This could be for reuse with solar panels, or another form of renewable energy, to store excess electricity generated for use later in the day. As well as storing renewable energy EV batteries can be used to buy and store cheap, off-peak energy for use during peak times when energy is more expensive. 

Separating battery parts - EV batteries can also be recycled by being recycled for parts. The battery can be broken down and valuable raw materials such as lithium, nickel and manganese extracted to be reused. 
 

Environmental impact of electric car batteries 

There are some downsides to electric car batteries. Lithium and other rare materials used are finite resources, just like fossil fuels. Mining these materials has been linked with water contamination, air contamination and damage to local ecosystems, while manufacturing EV batteries can result in high carbon emissions. 

The difficulty of directly recycling lithium batteries without disposing of some components and the limited lifespan of the current generation of batteries also have an environmental impact. 

Learn more in our guide to whether electric cars are better for the environment. 

FAQs 

What is an electric car battery lease? 

An electric car battery lease works in a similar way to other vehicle lease schemes. In this case, instead of leasing the vehicle you lease the battery. Renting the battery means the leasing company is responsible for any repairs or replacements needed. 

How big is an electric car battery? 

Electric car batteries are much bigger than petrol or diesel car batteries. They typically take up a large proportion of the underside of the vehicle. This is because the battery is made up of multiple cells joined together to give the battery the capacity it needs. 
 
How much does an electric car battery weigh in kg?

An electric car battery’s weight will usually depend on the battery capacity. A greater capacity will need more battery cells, which will add more weight. The average electric car battery weighs around 450 kg — the same as an entire petrol-powered Fiat 500.   

Charge your EV battery with Power NI 

 
Help to extend your EV battery’s lifespan with Power NI’s range of home EV chargers. You can start, stop and schedule charging sessions to avoid overcharging or running your EV battery flat. 

Switch to our EV Nightshift tariff to swap battery-zapping rapid charges for cost-effective, overnight charging sessions at reduced rates.