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Electric Car Batteries: Why Weight Matters

Electric Car Batteries: Why Weight Matters

By James Fisher

The Growth of EV Adoption

In recent years, electric vehicles (EVs) have become a common sight on our roads, with sales surging rapidly across the world. Registrations of new EVs were up by 40% in 2022, and in the UK, the sale of new electric cars finally overtook diesel cars for the first time. As more drivers are making the switch to EVs, one of the main differences they encounter is the heavy battery that powers the car. In this article, we’ll take a closer look at the weight of electric car batteries, what affects their weight, and how it impacts driving and handling.

EV Battery Weight

The weight of an EV battery depends on its size and energy storage capacity, with larger batteries able to store more energy but weighing more too. The average weight for EV batteries is around 454 kg (1,000 pounds), but some can weigh as much as 900 kg (2,000 pounds). The battery can also make up as much as 25% of the overall weight of the vehicle. However, the weight of the battery can improve a car’s range, though in turn, it requires more energy as well.

What Determines Battery Weight?

EV batteries are made up of thousands of individual cells that are connected to form a large battery pack. Lithium-ion is the most popular battery chemistry used in EVs due to its cost efficiency and high energy density. On average, around 60% to 75% of a battery’s total weight comes from the cells and the materials they contain, while the remaining 25% to 40% is comprised of the battery’s metal casing, cables, thermal and battery management systems (TMS and BMS). Besides lithium, EV batteries also contain minerals like cobalt and manganese, with a typical EV battery containing around 8kg of lithium, 14kg of cobalt and 20kg of manganese.

Comparing Energy Density

Energy density refers to the amount of energy a battery can store within a given weight. Lithium-ion batteries have a typical energy density of about 260-270 watt-hours per kilogram (Wh/kg), making them much preferred over traditional lead-acid batteries with energy density around 50-100 Wh/kg. However, research into new battery structures and manufacturing processes is ongoing, with expectations to push energy density to 350 Wh/kg, which can potentially increase an EV’s range while decreasing its weight.

EV Weight vs Petrol Car Weight

EVs weigh more on average than combustion engine vehicles, largely due to the heavy battery. However, the difference is not straightforward. While EV batteries are heavier, their motors are much smaller and lighter than an internal combustion engine. Another factor that counterbalances the extra weight of the battery is the use of lightweight materials such as magnesium alloys, aluminium alloys, carbon fibre, and polymer composites, which can reduce the vehicle’s weight by up to 50% and make it more efficient.

Impact on Driving Specifications

Besides the added weight, the shape and placement of EV batteries help to boost specific driving specs and safety. In most cases, the battery pack is a long, flat, rectangular block placed under the floor of the cabin. This helps to bring the car’s centre of gravity down, which, combined with the extra weight from the battery, makes it much more stable to drive. EVs can deal with tight curves at high speeds with little body roll and are easier to drive in wet, icy, or snowy conditions.

EVs’ weight also contributes to passenger safety. These cars’ low centre of gravity makes them less likely to roll over in an accident than petrol cars. Moreover, the added weight in the battery can often help to protect passengers in case of a crash by reducing the impact’s severity.

Advancements in EV Battery Technology

As the primary power source for EVs, batteries are a crucial component, and their weight is directly proportional to how much power (and therefore, range) can be delivered. However, researchers are continuously working to improve EV battery technology, with advances in energy density, lighter materials, and improved manufacturing processes anticipated to increase the range, consistency, and reliability of EV batteries.

In conclusion, the weight of an EV battery can vary greatly, depending on the vehicle and the battery size. While the weight of the battery can impact driving and handling, the shape and placement of the battery can help improve safety and stability. As the EV market continues to grow, improvements in technology will inevitably lead to more compact and lightweight batteries that offer greater performance and durability, ultimately accelerating the uptake and acceptance of electric vehicles.

Written by James Fisher
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