Can electrics with heavy batteries damage the roads?

Large batteries allow electric cars to have greater autonomy, approaching the convenience of combustion models as to the possibility of long distances.

But they are also heavier, as are the vehicles that equip as a result. And the impact of this greater weight on the roads is of concern to the founder and executive director of Chinese automobile manufacturer NIO, William Li.

According to Yicai, the leader said during a recent conference in China: “Some cars have 120 kWh batteries that weigh 700 or 800 kg. The weight doesn't matter much to the car itself, but has anyone calculated the impact on the roads? With a weight 1.2 times greater, the damage to the road is 2.07 times greater“.

The basis for such a statement is the so-called “fourth law of power”, which theorizes that the damage caused by a motor vehicle to the floor is proportional to the fourth power of its axle load. That is, an increase in weight means a greater wear caused to the road.

This relationship was first established in the late 1950s by the American Association of State Highway Officers, according to a report for the NZ Transport Agency of New Zealand. If the weight is twice as high, the fourth power of two is 16 – that is, the damage would be 16 times greater.

Last May, the same William Li had already addressed the matter in statements to the same body: “If the more than 300 million vehicles in China became all heavy, our roads would essentially be crushed.”.

At NIO, Yicai counts, its executive demands its personal signature for each kilogram of weight gain of a model, while batteries normally weigh between 400 and 500 kg. The result is that cars have less autonomy.

The current NIO offer for Portugal includes three models, with batteries of 75 kWh or 100 kWh. The exact weight of the batteries is not known, but the models are known: SUV EL6 weighs 2,323 kg (tara) with the larger battery, while ET5 goes up to 2,160 kg (berlina) or 2,210 kg (Tourer car).