If you’re interested in making the switch from fossil fuels to electric driving, then the fundamental change you’ll be making is moving from a car that’s powered by an internal combustion engine (ICE) to a car that’s powered by a large pack of batteries. That can feel like quite a change, so here’s some information on what it all means.

How electric car batteries work

Internal combustion engine cars get their energy from burning petrol or diesel, while an electric vehicle gets its power directly from a set of scaled-up lithium-ion batteries. Unlike a mobile phone battery (which is a single battery, and isn’t designed to last for years and years), an electric car battery is made up of thousands of individual lithium-ion (Li-ion) cells working together.

When the car is charging up, electricity is used to make chemical changes inside the batteries, in order to store charge. Then, when the electric car is on the road and charge is required, these chemical changes within the batteries are reversed in order to produce electricity.

Lithium-ion batteries

Lithium-ion (Li-ion) batteries are rechargeable batteries used in electric vehicles and in some portable electronic devices. They have a much higher energy density than typical lead-acid or nickel-cadmium rechargeable batteries, which means the battery pack can be compressed in size, or is much smaller than it otherwise would be, which means more can be used inside electric cars to provide a long range.

Lithium is the lightest of all metals, however lithium-ion batteries don’t actually contain any lithium metal, and instead they contain ions. An ion is an atom or molecule with an electric charge that’s caused by the loss or gain of one or more electrons.

Lithium-ion batteries are safer than many alternatives, and electric car and battery makers also add in other safeguards within the batteries, to protect them during repeated rapid charging.

Electric car battery charge and discharge

Electric car batteries go through cycles of charge and discharge, that occur when the car is plugged in, and then when its driven.  Repeating this process repeatedly over time affects the amount of charge the battery can hold. The result is a decrease in range and thus the need to charge the electric car sooner on long journeys (over 100 or 200 miles etc). However the reduction in range is a lot less and a lot slower than many people think. A study using a Tesla found that after 300,000 miles (the equivalent of 40 years of average driving distance in the UK) the battery still had 82% capacity.

Most manufacturers have a five to eight-year warranty on their cars/batteries. However, the current calculations are that an electric car battery will last for between 10 and 20 years before it needs to be replaced, which is quite remarkable.

How an electric car motor works

The way that an electric car motor is powered is a lot simpler than a traditional combustion engine. The battery simply connects to one or more electric motors, which drive the wheels. (A Nissan Leaf has one electric motor at the front axle, while more performance-focused models like the Jaguar I-PACE have one motor on the front axle and one on the back, making them four-wheel drive).

When you press the accelerator the electric car instantly feeds power to the motor, which gradually consumes the energy that is stored in the batteries.

Electric motors also ingenuously work as generators, so that when you take your foot off the accelerator and the car begins to slow down, the system converts the forward motion back into electricity. This happens more strongly if you actually press on the brakes, thanks to regenerative braking, which uses the kinetic energy that would otherwise be lost, when slowing and stopping, and stores it in the battery, along with thermal energy from the brake pads and tyre’s heat friction, to generate charge and thus improve the electric car’s range.

Capacity and kWh

Kilowatts (kW) are units of power, that show how much energy is required for a device to work. A kilowatt-hour (kWh) is a unit to show how much energy has been used. For example, a  100 watt lightbulb uses 0.1 kilowatts per hour.

The average family home uses 3,100 kWh a year for all it’s electrical devices, while charging an electric car from home uses about 2,000 kWh.

Electric car battery life

The battery on an electric car is a proven technology that will last for many many years. In fact, electric car manufacturers guarantee it. Nissan warrants its electric car batteries for eight years or 100,000 miles, and Tesla and MG offer similar guarantees.

This might seem incomprehensible given that battery charge in your mobile phone begins to wane out after only a couple of years, but as stated above, it’s a different type of lithium-ion battery used for mobile phones, that aren’t designed to stand the test of time. Also, during ownership of mobile phone time it might be fully charged and discharged hundreds of times (rather than smartly managed between 20-80%) and each of these charge cycles count against the life of the battery. After perhaps 500 full cycles, a lithium-ion phone battery begins to lose a significant part of the capacity it had when new.

That’s fine for a mobile phone, but your new electric car has to last many thousands of miles, so manufacturers go to ingenious lengths to make electric car batteries last longer. In an electric vehicle the batteries are ‘buffered’, meaning that drivers can’t use the full amount of power they store, which reduces the number of cycles the battery will go through. Together with other techniques, such as clever cooling systems, it means that electric car batteries ensure many many years of high charge and range.

In fact, in order to preserve the life of an electric vehicle battery, manufacturers create additional spare capacity, to compensate for the slight degradation over time. This means that as an electric vehicle ages and the battery goes through many cycles, that additional spare capacity is added, which allows the range of the vehicle to stay the same throughout the life of the battery. And then eventually when the battery capacity falls below 80% after many many years, drivers may start to notice a fall in the range and performance of the battery.

Electric car battery replacement

Many manufacturers provide a warranty of up to 8 years or 100,000 miles, meaning that if you did need to replace the battery for any reason, then it would be covered by the warranty. On our model pages you can find out the warranty offered for any electric car model.

For anyone who would want to replace their electric car battery, after 10-20 years when range has diminsihed, the good news is that the cost of batteries has fallen dramatically in the last decade, as the industry of electric car batteries develops at a huge scale. The cost of batteries has fallen by 100% or more in the last ten years. A new 40kWh battery would cost well under £10,000, and some estimate that the prices will fall below $100/kWh by 2030, at the time when the UK government aims to have 50% of all new vehicles sold as all-electric.

Electric car battery recycling

The time that batteries spend in an EV is often just the beginning of their useful life. Once removed from a car, most batteries will still be fit for other demanding jobs like energy storage in the electricity network, or in a home, which is a growing area of demand.

When batteries do reach the end of their working life, they are recycled, which typically involves separating out valuable materials such as cobalt and lithium salts, stainless steel, copper, aluminium and plastic. At the moment only about half of the materials in an EV battery pack are recycled, but with EVs sales soaring, car brands are looking to improve on their recycling. VW are currently working towards a target of recycling 97% of their battery components.

Repurposing EV batteries could create a closed-loop system for recycling. Meaning that the factories that produce the batteries could eventually be powered using the repurposed batteries once their lives powering vehicles comes to an end.

Find the right electric car for you

Using our search tool you can choose what type of electric car you want, and add in your specific preferences to get a list of electric cars that will suit your needs and wants. Every model page has information about the car’s range, battery, warranty, and much much more. Explore your options now!