Electric vehicles confront a significant challenge: Weight issues

The subject of electric cars is broad. We have spent considerable word-counts mansplaining hybrids, plug-in hybrids, and fully electric cars, as well as providing advice on what to consider when purchasing an electric vehicle.

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EVs are more friendly to the ecosystem than ICE-powered vehicles; they are improving in terms of range, price, and technology. However, there is one significant challenge that remains to be addressed: the weight of these vehicles. EVs are generally heavier than cars powered by internal combustion engines (ICE) because of the large battery packs located beneath the floor. For instance, let's look at the BMW 420d Gran Coupe, which has a reasonable weight of 1,705kg. In comparison, its electric counterpart, the i4 M50, weighs considerably more at 2,215kg due to its high-capacity 83.9kWh battery pack.

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On that note, the GMC Hummer EV is classified as a Class 3 medium-duty truck in the US of America due to its massive weight of just over 4 tonnes. But why do EVs have such a weight disadvantage? After all, they are only batteries, right? Well, yes, but there are also other factors to take into account, like electric motors and additional reinforcement of the suspension system due to the extra weight. As for the battery packs, they are usually made of lithium-ion cells, which are quite heavy. These batteries store the electrical energy that propels the vehicle. In essence, giving a car hundreds of kilometres of driving range means slinging a huge, heavy battery to the bottom of the vehicle. 

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Manufacturing giants such as Toyota and Stellantis are working around the clock to find a workable solution to reduce the weight of these batteries. Stellantis, in particular, has set an ambitious goal to reduce the overall weight of EV batteries by 50% by 2030 by developing lighter and more affordable lithium-sulphur batteries, a key feature of the new Volvo EX30 as well. According to the multinational automotive manufacturing corporation, these types of batteries make use of less exotic materials compared to the normal lithium-ion batteries of today. 

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This initiative is largely driven by their investment in Lyten, a company specialising in lithium-sulphur batteries, a promising alternative to the traditionally used lithium-ion batteries. 

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What are the penalties for a heavy EV car? 

Until a viable solution is found by manufacturers to reduce the weight of their batteries in electric cars, these cars will persist in their inefficiency. The heavy batteries contribute to significant understeer, increased inertia, and added stress on the suspension system. 

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Back to the matter of efficiency, the weight of a car is an important consideration that affects its real-world driving range. A heavier car necessitates more energy for movement, which in turn affects its range due to the increase in energy demand. This could lead to rapid depletion of the battery and more frequent visits to the charging station.

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During our testing of the BMW iX1 xDrive30, which has a rated weight of 2,010kg and is fitted with a 64.7kWh battery pack, we were able to drive up to 380km on a single charge. It's important to note that the relationship between vehicle weight and range can be seen as linear because automotive engineers usually account for battery capacity in proportion to the vehicle's size. For instance, a large vehicle such as the Lotus Eletre R employs a 112kWh battery pack that feeds power to two electric motors to help carry the 2,640kg behemoth. 

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When it comes to the topic of understeering in the realm of EVs, they tend to have a lot of that due to the weight of the battery packs. In that case, they tend to have weight distribution differences compared to ICE-powered cars. The vehicle's weight can have an impact on the handling characteristics, particularly in cornering situations. For instance, the BMW i4 M50, which weighs 2,215 kg, demonstrated a tendency to understeer well before the perceived limit during our 2022 Speed Week event around Slaaihoek. 

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Another penalty of EVs weighing more than their ICE counterparts is inertia, simply because the heavier the car, the longer its braking distance becomes. This simply means that a heavy car would take longer to stop than regular cars, thus posing a safety risk in emergencies. Also, greater inertia can cause more wear and tear on the car’s components, such as brakes and tyres. 

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Though EVs tend to have some of the best passive and active safety systems in place, several experts and organisations have raised concerns about the increased severity of accidents. For instance, a study estimates that a 450kg increase in vehicle weight has the potential to result in a 47% increase in fatality risk. Furthermore, the risk to vulnerable road users, such as pedestrians, cyclists, and motorcyclists, is also a serious concern. The additional weight that EVs carry can result in more severe injuries in a collision with these road users.

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Finally, the higher weight of EVs can put additional strain on the suspension system, thereby impacting its performance and longevity. While this is a concern, carmakers are working feverishly to address the issue as EV adoption is growing at a rapid rate. EVs, though, despite their bulk, represent a crucial step forward in terms of sustainability, as the world is collectively working towards a single goal: zero emissions.

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It is therefore essential that the aforementioned challenges be solved in order to enable a smooth transition to a more sustainable mode of transportation. 

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