Do not go gentle into that good night, cars should run and rave at close of day. Range, range against the decaying battery.
Yeah, it’s a bad ripoff of Dylan Thomas’ poem about growing old but it’s a great metaphor for what Mercedes-Benz just achieved with its all-electric, very streamlined Vision EQXX concept car. Displaying another 87 miles of range still to go—the thing didn’t even run empty—this road legal concept was able to pull off an 11-hour, 32-minute run without ever stopping to charge its battery. On real roads and at real road speeds as it went from Sindelfingen, Germany to Cassis in Northern Italy. For those without a map of Europe handy, that translates to a total distance of 1,000 km, or 621 miles, at an average speed of just over 54 mph.
An Epic Journey for EV Technology
The trip started on a cold, rainy morning in Sindelfingen. The goal, of course, was to run the EQXX further on a single charge than any other electric vehicle had before. With Germany’s TUV—a certification body that works on everything from vehicles and their aftermarket parts to household electronics—coming along and even tamper-proofing the charge port, Mercedes and the Vision EQXX set off for one incredible record-snatching journey. The achievement makes the EQXX, per Mercedes, the longest-range road-legal EV yet, though we should remind you again that though the EQXX is road-legal, you can’t exactly buy one, so it’s not technically a “production car.”
While the EQXX’s first portion of the a run landed it on the Autobahn at 87 mph, the rest of the drive included driving through the Swiss Alps and the Gotthard Tunnel, regular street driving around Milan, and down to Cassis, Italy, via the road along the Cote d’Azur where the EQXX finished in the late evening. For 11 hours and 32 minutes, the 621-mile endurance test would end with an average average speed of 54.43 mph. Even after that nearly 12 hour drive, the 8.7 kWh per 62 miles of consumption average of the EQXX meant that it still could have traveled another 87 miles using what energy was left in the battery.
Even if you set aside the unused 87 miles of range, the EQXX (which, granted, has not been and won’t be EPA-tested) smashes the official range figures for current champions in this arena, the Tesla Model S (405 miles) and Lucid Air (up to 520 miles per the EPA). Factor in the 87 miles, and the EQXX had the potential to go over 700 miles between charges. That’d be an impressive range for an internal-combustion vehicle, let alone a streetable EV prototype.
The Technologies Involved
It was also a demonstration of the EQXX’s high-silicon anode, high-energy density battery that’s air-cooled rather than water-cooled. That means, despite only being a 100-kWh capacity battery pack, the pack is 50 percent smaller in volume and 30 percent lighter than the 108-kWh pack on the Mercedes EQS. The battery measures out to 78 x 50 x 4 inches and weighs just 1,091 pounds. In order to keep the battery cool, the Vision EQXX utilizes permanent passive cooling with an underbody cooling plate. This gives the battery an amazing energy density of nearly 400 Wh/liter while allowing for close to 900 volts in operating voltage.
While the battery is air-cooled, the 180-kW Formula 1-derived motor isn’t. However, the drive motor’s water-cooling allows Mercedes engineers to construct an active, on-demand cooling system that would open and close shutters at its radiator openings as needed to keep the system cool. Those shutters would also open when the air conditioning system needed its condenser to be cooled so the cabin remained at a comfortable temperature during the drive with a minimum of excess aerodynamic drag from body openings.
Cabin heat, on the other hand, is controlled by a heat pump that draws air sources from the heat exchanger and the drivetrain to regulate the temperature. Powering it and the entire 12-volt system is a solar roof made of 117 solar cells that reduce the draw from the drive battery. It also uses its regenerative system during braking and during coasts to recuperate lost energy while the entire drivetrain is further optimized to reduce losses by 44 percent over a standard electric vehicle drivetrain.
The EQXX’s amazing range is also due to using lightweight materials. The most interesting of note is the use of aluminum brake discs as the energy recovery system in the EQXX is strong enough to reduce the use of the hydraulic brake system. The rear floor also uses a new aluminum casting process allowing the use of a single part over multiple parts that would have increased its weight.
On top of that, anywhere the structure didn’t need extra strength, gaps were formed to reduce weight even further. While a metal plate is required to help passively cool the battery, its top is made of a new carbon-fiber-sugar composite. All told, the Vision EQXX weighs in at a svelte 3,869 pounds.
That weight is handled by a set of Bridgestone tires made just for the Vision EQXX that have a rolling resistance rating of just 4.7 for a tire that is sized at 185/65R20. That’s significantly lower than the tires used in the EQS, which have a rolling resistance of 5.9. The low resistance is achieved by a new tire technology that reduces tire deformation while driving as well as a tire belt that is tensioned higher than a standard tire. Bridgestone not only reduces the rolling resistance, but also the weight of the tire by 20 percent.
Air resistance is also a huge detriment to achieving high efficiency, which is why the EQXX features more than just the shutters mentioned earlier. The transition from the tire to the rim of the wheel is another part that was optimized for aerodynamics on the EQXX. The entire body was also sculpted for maximum aero efficiency and reduced drag for a CoD of 0.17 at maximum aerodynamic efficiency. That’s not bad for a vehicle with a frontal area of 22.82 square feet.
While the Vision EQXX is a one-off, the technologies made within it are all going to be carried over into the next fully-electric vehicles from Mercedes-Benz. While aluminum disc brakes, high-silicon anode batteries, and carbon-fiber-sugar composites are probably a while off for full production, the use of single-piece aluminum structures, improved heat pumps, and more efficient EV drivetrains aren’t and those along will lead to some impressive range figures in upcoming EVs from Mercedes.
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