Understanding EV Batteries: All You Need to Know

If you’re considering leasing an electric vehicle for the first time, you’ve probably got a few questions about their batteries. These mysterious technological beasts only arrived on the scene within the last ten years, so a lot of drivers are still in the unknown. 

Understanding how EV batteries work is essential to maximising the performance of an electric car. While you don’t need to know the ins and outs in ridiculous detail, learning about terms like EV battery capacity, kWh, and charging speeds is advantageous. 

In this guide, we’ll break down the basics to understanding EV batteries and discuss everything you need to know - from the differences between battery types to how they impact driving. 

We talk about: 

Put simply, an electric vehicle (EV) battery is a specialised power unit that stores and supplies electricity to power the electric motor. Unlike conventional car batteries, which primarily start the engine and electronics, EV batteries are the main energy source. 

They provide power for driving, acceleration, and all other essential functions. Essentially, they are similar to batteries found in modern-day tech devices, just much bigger and powerful. 

The key characteristics of an EV battery: 

• High energy density - EV batteries are able to store much more energy to allow for long-range driving. 
• Power delivery - They deliver constant power to the electric motor to ensure smooth performance. 
• Thermal management - Proper cooling is crucial to prevent overheating and maintain the efficiency of the battery. 
• Longevity - EV batteries are engineered to withstand thousands of charge cycles to ensure they remain operational for a long period of time. 

Like a normal engine, EV batteries come in a range of configurations that each offer unique benefits. The most commonly used batteries include: 

Lithium-ion batteries are the industry standard for modern EVs. Named because of the lithium-ion present in the EV battery components, they provide a great balance between energy density, weight, and safety. 

The battery consists of multiple cells, each containing a cathode (positive electrode) and an anode (negative electrode) that are immersed in an electrolyte solution. 

Solid-state batteries are a new technology in the EV space and are expected to be available in some electric cars as early as 2025. They use a solid electrolyte instead of a liquid, which improves energy density and safety. 

If you’re a bit of a novice, all those letters have probably terrified you. Let's simplify it for you: 

BEV = battery electric vehicle. PHEV = plug-in hybrid. HEV = hybrid. MHEV = mild-hybrid. 

Breaking it down to its simplest form, EV batteries operate through a three-pronged approach. 

• Charging phase - When plugged into a charger, electricity flows into the battery which causes a chemical reaction that stores the energy. 
• Discharging phase - When the vehicle is in use, the energy stored is released, generating an electric current that powers the motor. 
• Regenerative braking - A lot of EVs use regenerative braking, a system that recaptures energy when the vehicle slows down or breaks, feeding it back into the battery to help extend range. 

• Temperature - EV batteries are sensitive to temperature extremes. Excessive heat or extremely low temperatures can reduce the battery’s ability to deliver power and, thus, reduce range. 
• Charge and discharge cycles - Every time a battery is charged and then used, it undergoes a charge cycle. Over time, the number of charge cycles affects the battery’s capacity. Thus, more cycles lead to the gradual degradation of the battery. 
• Depth of discharge - The depth of discharge essentially means how much of the battery's energy is used before it is recharged. The larger the depth of the discharge, the more likely it is to shorten the battery’s lifespan. This is why manufacturers recommend you keep your battery within 10-80% at all times. 
• Charging speed - Rapid charging may be convenient, but it can strain the battery and lead to increased wear and tear. You should employ a mix of rapid and slow charging to prolong your battery's health. 

The capacity of an EV battery is measured in kilowatt-hours (kWh), indicating how much energy it can store. For example, an 80kWh battery can deliver 80 kilowatts of power for an hour. 

Typically, the larger the battery capacity, the more electric range it gets. 

The range of your EV depends on its battery capacity, efficiency, and driving conditions. When researching an EV, remember that manufacturers will always show the car's optimal range. They’ll say something like, “The car can reach a range of up to 250 miles”. 

‘Up to’ is the key there. That’s the car's range in optimal conditions, so it's pretty unlikely you’ll ever get there. It's best to lower your expectations and expect a real-world range of around 80% of the optimal range. 

Factors that affect an EV's range include the weather, the weight on board, whether you’re using in-car features, and the speed you’re driving. 

If you’re wondering how long it takes to charge an electric car, there’s no one answer. Charging speed depends on both your make and model of electric car and the charging capabilities it comes with. 

Chargers are measured in kW. The higher the kW, the faster the charger will add battery to your vehicle. 

Here’s a breakdown of the different EV chargers: 

• Slow chargers - Most slow chargers are rated up to 3kW, but it’s usually carried out between 2kW and 6kW. 
• Fast chargers - Fast chargers range from 7kW to 22kW and are often found in wall box chargers or at public charging stations. 
• Rapid chargers - A rapid charger is usually capable of charging at least 50kW and, in some cases, up to 90kW. 
• Ultra-rapid chargers - Ultra-rapid chargers are capable of charging at 100kW or more, reducing charging times to around the 25 minute mark (usually). It’s worth noting that not all cars are compatible with ultra-rapid charging, and if it is, it will cost more to charge at this speed. 

For more information, check out our guide, Charging Strategies for Efficient Driving. 

When it comes to electric vehicles, EV car battery capacity is more than just a number. It plays a pivotal role in determining range, efficiency, and even vehicle dynamics. 

What affects range? 

• Driving habits - aggressive driving or rapid acceleration can drain the battery faster. 
• Terrain - Driving uphill consumes more energy than cruising on flat roads 
• Weather conditions - Extremely cold weather can reduce the range
• Vehicle weight and aerodynamics - Heavier or less aerodynamic cars require more power and, thus, reduce the range 

How to maximise your EV battery range? 

• Drive smoothly - Gentle acceleration and braking can make a noticeable difference. 
• Precondition your car - Heating or cooling the car while it's still plugged in saves battery power. A lot of cars allow you to do this through their app. 
• Limit high-speed driving - Driving at high speed uses more energy, reducing overall range.

You need to keep in mind that batteries naturally degrade over time. Most EVs lose a small percentage of their capacity each year, depending on usage and charging habits. 

EV manufacturers offer a warranty for their batteries, which, on average, covers eight years or 100,000 miles (whatever comes first). For more information on warranty, take a look at our guide, What is Covered by a Car Manufacturer Warranty. 

If you’re looking for more electric car leasing advice, check out our comprehensive Electric and Hybrid Car Guides. 

We are also one of the UK’s largest car leasing brokers, offering a range of deals to suit your every need. For more information, check out our latest electric car lease deals or call us on 0345 811 9595.