Explanation of the weight of electric car batteries

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The weight of an electric vehicle (EV) battery depends enormously on the vehicle and the model. However, on average, EV batteries weigh in at around 300 kg, although the battery in a Tesla S can weigh up to 600 kg.

Generally speaking, the heavier the battery in an EV, the more energy it can store and the more power it can deliver. Although this link is not always systematic. A bigger battery can increase the vehicle’s range, but paradoxically its weight also means that it needs to consume more energy to move forward.

The growing adoption of electric vehicles

Electric cars were still a novelty a few years ago, but the French EV market is coming of age and electric is becoming the new norm. In 2022, electric vehicles accounted for 21% of total sales, almost double their market share two years earlier.

One of the main differences for new electric vehicle drivers is that they use a battery instead of a fuel tank. As well as recharging instead of refuelling, the handling of an electric vehicle is also affected by the battery because of its comparatively greater weight.

Below we look at how much electric car batteries weigh, what influences their weight and how this affects the car’s driving and handling.

Weight of an EV battery

The weight of an EV battery is determined by its size and the amount of energy it can store. In general, the larger the battery, the more energy it can store and the heavier it is. For example, 6 to 12 kilowatt-hour (kWh) batteries typically weigh between 100 and 150 kg, while 60 to 100 kWh batteries weigh between 350 and 600 kg. Obviously, the weight of an EV battery varies from car to car, and depends enormously on the size and weight of the car. Here are a few examples of batteries in popular EV models:

• A Tesla Model S has a battery weighing around 600 kg;
• a Tesla Model Y has a battery weighing around 771 kg ;
• In comparison, the Nissan Leaf’s battery weighs just 303 kg, which is about average.

As you can see, the weight of an electric vehicle battery is considerable and can represent up to 25% of the total weight of the vehicle. To understand why, we first need to look at what EV batteries are made of.

What determines the weight of electric car batteries?

Although they appear to be made up of a single unit, EV batteries are actually made up of thousands of small cells linked together to form a large battery pack. By far the most popular battery chemistry for EVs is lithium-ion, thanks to its low cost and high energy density, which offer the best balance between price and energy storage capacity.

So what does an EV battery weigh? On average, around 60-75% of a battery’s total weight comes from its cells and the materials they contain, while the remaining 25-40% is made up of the battery’s metal casing, cables and thermal management system (TMS) and battery management system (BMS).

As well as lithium, EV batteries also contain other minerals, such as cobalt and manganese. A typical EV battery contains 80% nickel, 10% cobalt and 10% manganese, although this proportion can change depending on the battery. A battery generally contains between 3 and 5 kg of lithium, although the battery in the Tesla Model S contains around 62.6 kg.

Energy density of an electric vehicle battery

Energy density refers to the amount of energy a battery can store in a given weight. In other words, the higher the energy density, the more energy a battery can store at the same weight.

The energy density of EV batteries is an important factor that determines how much power a battery can produce and for how long. It therefore determines the EV’s range. A high energy density reduces the total weight of the battery while storing as much energy as possible to maximise the car’s range.

Compared with traditional lead-acid batteries, which have an energy intensity of around 0.027 kWh/kg, lithium-ion batteries have a typical energy density of around 0.2 kWh/kg. This makes lithium-ion batteries the preferred solution for any compact device requiring a long-life battery, such as phones, laptops and, of course, electric cars.

While lithium-ion batteries already have a high energy density, there is a huge amount of research underway to improve this even further, with new battery structures and manufacturing processes that should push energy density up to around 500 Wh/kg, allowing new electric vehicles to improve range while reducing weight.

Qu’en est-il du poids des batteries de voitures traditionnelles ?

It may seem obvious when you think about it, but unlike combustion-powered cars, electric car batteries are not just for starting and switching on your headlights. EV batteries are the primary source of power for electric vehicles and need to hold much more energy than a traditional car battery with a combustion engine.

Because they contain so much more energy, they are considerably larger and heavier than conventional car batteries. This is why the weight of a conventional lead-acid car battery is only 10 to 30 kg, whereas electric vehicle batteries generally weigh several hundred kilograms.

Are electric cars heavier than combustion-powered cars?

If there is such a weight difference with conventional car batteries, do electric vehicles also weigh more overall? The answer is generally ‘yes’. EVs tend to be heavier than internal combustion cars, mainly because of the weight of their batteries.

Cela étant, cette différence n’est pas aussi évidente qu’on pourrait le penser.  

While electric vehicle batteries are heavier, their motors are much smaller and lighter. Replacing metal parts with plastic polymers can reduce vehicle weight by 8 to 10%. By combining them with high-strength steel, magnesium or aluminium alloys, and carbon fibre, they can cut weight by 50% and reduce the vehicle’s fuel consumption, making it even more efficient.

Impact of electric car battery weight on driving characteristics

Contrary to what you may think, a heavier battery can actually often significantly improve driving, handling and safety characteristics. In addition to their weight, this is due to the shape of the EV battery and its location: generally, they form a flat, elongated rectangular block, typically placed under the floor of the passenger compartment.

This lowers the car’s centre of gravity, which, combined with the high weight of the battery, greatly improves the car’s stability. In terms of handling, this means that EVs can easily tackle tight bends, even at higher speeds, with little roll. They are also much easier to drive in rain, snow or on icy roads.

In addition to manoeuvrability, the weight of electric vehicles greatly improves passenger safety. Because of their low centre of gravity, they are much less prone to accidents than combustion-powered cars, and their high weight can often help to protect passengers in the event of a collision, by reducing the magnitude of the impact.

Advances in battery technology for electric vehicles

Newcomers to the world of electric vehicles are often surprised to discover the weight of the battery, which accounts for a significant proportion of the vehicle’s total weight. As the car’s main power source, the battery is a critical component of electric vehicles, and its weight is directly proportional to the amount of energy needed to power the car (and therefore its range).

At the same time, technological advances in batteries for electric vehicles are improving their energy density, enabling carmakers to obtain greater autonomy from batteries of the same size. In addition, new materials are making EV batteries lighter, making them more efficient in terms of energy distribution.