Mercedes to ditch wheel brakes and paint EVs with solar cells

German carmaker Mercedes is ‘reinventing’ braking on electric cars by ditching the classic wheel brake disks and moving the braking system into the electric drive unit at the front or rear axle. This system is more efficient, quiet, and virtually maintenance-free for the car’s lifespan, and brake dust is kept inside without the need for cleaning up.

The in-drive brake is only one of the ‘Pioneering innovations for the car of the future’ the carmaker showed journalists, giving insights into research activities and future technologies. Another nice-to-have: A new kind of solar paint could generate enough electricity for more than 12,000 km per year.

An ultra-thin layer of solar cells

The ‘solar paint’ uses a new type of solar modules that could be seamlessly applied to the bodywork of electric vehicles—similar to a wafer-thin layer of paste. At 5 micrometers, they are significantly thinner than human hair, weigh just 50 grams per square meter, and are packed full of energy, Mercedes says.

The solar cells generate energy nonstop, even when the car is parked, and are used for driving or fed directly into the high-voltage battery. Under ideal conditions, the engineers say an area of 11 square meters, somewhat equivalent to the surface of a mid-size SUV, could produce energy for up to 12,000 kilometers a year.

No more wheel brakes

Braking is another area in which EVs can improve their sustainability, and different parties have worked on several solutions. All electric cars today brake partly through recovery, using the car’s electric motor to slow down the vehicle and replenish the battery with the electricity it produces.

Most EVs allow you to set the pace of regeneration to a level where you seldom need the actual wheel brakes to come to a complete stop by just releasing the throttle. That’s the so-called ‘one-pedal driving.’ Hyundai and Kia, for instance, offer paddles on the steering wheel to adapt the setting instantly; others often burry it into their software menus.

Mercedes goes one step further and prepares to ditch the wheel brakes altogether and replace them with an in-drive system. There will be no traditional caliper grips on a disk, but a circular brake pad spins onto a water-cooled stationary disk with the motor.

No maintenance, no dust

The carmaker says this system needs virtually no maintenance throughout the car’s lifespan and has the additional environmental advantage of keeping all brake dust inside without the need to clean it. Another benefit is that it allows for totally closed-wheel rims, improving aerodynamics and lowering energy consumption.

Coping with brake dust might become very important, as the pending new Euro 7 vehicle-emissions regulations include a significant new sustainability wrinkle: first-ever restrictions for particulate emissions from brakes and rules on microplastic emissions from tires.

Sucking away microplastics

However, the Mercedes approach has no solution yet for tire particles. That, the German Aerospace Center (DLR) and the German engineering firm and racing team HWA ‘solved’ in a rather radical solution in what is called the world’s first truly nearly ‘zero-emission’ car as it even prevents fine particles from brakes and tires in the air.

The ZEDU-1 doesn’t have classic brake disks and calipers on the wheels, but these are also incorporated with the transmission into the e-motor. With specially developed high-performance electronics, that unit controls the force used by an ‘induction brake’ that regenerates the EV’s energy and only activates the integrated multiple-disk brakes when needed at higher speeds.

It allows for a very compact multi-disk brake system in an oil bath. All the abrasive particulate matter ends up in the oil, continuously pumped through a filter and cleaned.

The ZEDU-1 prototype tackles most of the tire’s microplastic pollution problem by encapsulating the wheel entirely and adding aerodynamically adapted components to the vehicle. When driving, these aerodynamic adaptations create a negative pressure that sucks away the microplastics from the tire wear like a vacuum cleaner, helped by an incorporated fan and blown through a filter system.