Electric car batteries are usually lithium-ion batteries, similar to the battery in your mobile phone or laptop.

An electric car battery is made up of thousands of individual rechargeable cells. Each cell contains two electrodes (positive and negative) separated by a liquid electrolyte. The negative electrode stores lithium ions. When the vehicle is driving, the battery releases electrons from the negative electrode, which flow through an external circuit to power an electric motor. The positive lithium ions simultaneously move through the electrolyte to the positive electrode.

Recharging works by reversing the process above. When the EV battery is connected to an external power source (like a charging station or home EV charger), the flow of electrons and lithium ions is forced backwards. This pushes the electrons back into the negative electrode and the lithium ions back to the positive electrode which recharges the battery for future use.

You measure an electric vehicle’s battery capacity in kilowatt-hours (kWh). You might recognise it as the same unit that your home’s electricity meter uses to show you how much you’ve used.

Here’s a handy analogy that might help. Think of electric vehicle battery capacity like a fuel tank’s capacity. The kWh represents the potential energy stored in the battery, just like a fuel tank indicates how much petrol it can hold. An electric car with a 60 kWh battery has a larger 'energy tank' than one with a 40 kWh battery, potentially allowing it to travel further on a single charge.

The average capacity of an electric battery is around 40kWh, but you can get some up to 100kWh. Generally, the larger the electric vehicle battery capacity the further you can drive before you need to recharge. As technology advances, the capacity of electric car batteries is likely to improve.

You'll find a wide range EV battery capacities across different car models. Smaller city cars might have batteries as small as 30kWh for shorter commutes, while high-end, luxury or very large EVs can have battery capacities exceeding 100kWh.

Bigger battery capacities typically increase the cost of an EV, so think about your individual driving needs when choosing an EV. If you mainly drive short distances within a city, a smaller battery might be your best option. If you’re more of a long-distance driver then it might be an idea to opt for an electric car with a larger battery that will be capable of longer ranges.

Electric car batteries can last a surprisingly long time. While estimates vary, most experts agree that EV batteries can last around 10-20 years, potentially covering up to 200,000 miles or more. A number of manufacturers offer warranties for batteries which depend on age or miles covered.

As with any battery, electric car batteries will degrade over time with repeated charging and discharging cycles. However, you can extend your battery's lifespan, by avoiding extreme temperatures, keeping your use of fast-charging to a minimum, and not fully depleting the battery regularly.

The good news though is that even at the end of its lifespan, an electric car battery can still be recycled, which further adds to the environmental case for choosing an EV.

Here are a few easy ways you can extend your EV battery's lifespan:

It is possible to repair an EV battery but the repair process can be challenging and often requires specialised training and equipment. Electric car batteries are made up of modules, which can be repaired rather than replacing the whole battery.

Due to the tricky nature of the work though, there aren’t many companies offering EV battery repair in the UK at the moment.

The cost of replacing your EV battery can vary depending on the make and model of your car. If you need to replace your battery within the warranty period then your car manufacturer should replace it at no extra cost.

Outside of your warranty you’ll need to talk to your EV’s manufacturer to get a quote for battery replacement.

Inside an EV battery are lots of very rare and expensive metals like cobalt, nickel and lithium, which means they cost a lot to produce when compared to diesel and petrol car engines.

Manufacturing electric car batteries is also a highly technical process which involves specialised facilities and technology. As with most new technologies, costs are coming down over time, but it will be a while until EVs become as cheap as petrol equivalents.

It’s always worth remembering though that the overall cost of owning and running an electric car can be lower than a petrol equivalent due to savings on fuel and maintenance.

Solid state batteries represent the next big leap in electric car battery technology. They use a solid electrolyte rather than the liquid or polymer found in current lithium-ion batteries. This means that solid state batteries can be more compact and energy-dense allowing EV manufacturers to fit lots more capacity into a smaller battery. Solid state batteries will hopefully be able to deliver a lot more range in a smaller package.

What’s more, solid-state batteries are potentially safer and more stable than liquid electrolyte batteries which could reduce the risk of fires or overheating. Solid state batteries are still in development by the major EV makers, but they have the potential to revolutionise electric vehicles.