One of the challenges of racing an electric vehicle (EV) is charging its batteries. Whether at the local drag strip, the Bonneville Salt Flats, or an international road racing circuit, finding the juice to power a racer is a real problem. This is especially true for Volkswagen, whose I.D. R Pikes Peak electric racecar will compete at the historic hill climb in the mountains of Colorado on June 24.
The road up the mountain on which racers compete is remote. The course starts at a temporary paddock in a campground at 9,000 feet and ends, after 12.4 miles and more than 156 corners, at the summit of Pikes Peak at 14,115 feet. Volkswagen’s I.D. R Pikes Peak racer’s two electric motors can generate a total of 670 horsepower. Its lithium ion battery pack is split into two sections, next to and behind the driver. The pack is reported to have a capacity of 40 kilowatt-hours. Charging this battery pack is where the challenge arises.
|Volkswagen's Pikes Peak racer is charged on the side of the mountain by a generator fueled by environmentally friendly Glycerol. (Image source: Volkswagen A.G.)|
Out of the Ordinary
If this were an ordinary EV race, you would just charge your battery to 100 percent and run your race. But Pikes Peak is no ordinary race. The paddock where the pits are located is at 9,000 feet above sea level. The temperature during the day can range from below freezing to over 90 degrees. “The ideal temperature for the battery is about 86 degrees Fahrenheit,” noted Marc-Christian Bertram, head of electrics and electronics at Volkswagen Motorsport, in a press release from the company. Charging heats a battery, and a cooling system has been engineered to keep the battery near its optimum temperature while it is charging.
There were also no adequate electrical hookups in the paddock, so Volkswagen Motorsport needed to bring its own generator system to power its chargers. A diesel-fueled generator would work, but the vision of clouds of sooty diesel exhaust employed to charge a zero-emissions racecar was something the company wanted to avoid. Instead, it fuels its generator with Glycerol, a sugar alcohol that is a byproduct of bio-diesel production. “The Glycerol-powered generator not only supplies the I.D. R Pikes Peak with environmentally friendly electricity before the practice sessions and the race, but also all the electrical devices in our pit area during the race, from the engineer’s laptops to the coffee machine,” said Bertram.
Just 20 Minutes
But a bigger challenge than the remoteness of the venue comes from a paragraph in the Pikes Peak regulations. If a participant must suspend their run for safety reasons—if another competitor crashes, for example—they have just 20 minutes to prepare for a second attempt and return to the starting line. Because 20 minutes is very little time to recharge a battery, the team needed a strategy to account for this possibility.
“When determining the charging strategy, we had to bear in mind a possible restart,” said Bertram. “With that in mind, there were two major challenges that had to be overcome: to avoid overheating the battery during the charging process, and to ensure that all the battery cells are charged equally.” Volkswagen Motorsport developed two charging systems that operate at the same time, producing a total output of 90 kilowatts. This is not a high-power charger and Bertram notes, “The low charging current limits heat development.” Besides, the (relatively) small size of the pack allows it to be charged in a short time, particularly if it is only partially depleted.
Can the team break the existing record of 8:57.118 minutes in the Pikes Peak electric prototype class? The Race to the Clouds takes place on June 24. Regardless of the outcome, what Volkswagen has learned from building and testing its first fully electric racing car is sure to benefit the upcoming line of I.D. electric production cars long into the future.
EV's have a future in motorsports. Design News Senior Editor will present "Faster With Electrons: Breaking EV Land Speed Records" at the Open Tech Forum of The Electric and Hybrid Vehicle Technology Expo, September 11-13 in Novi, Michigan.
Senior Editor Kevin Clemens has been writing about energy, automotive, and transportation topics for more than 30 years. He has masters degrees in Materials Engineering and Environmental Education and a doctorate degree in Mechanical Engineering, specializing in aerodynamics. He has set several world land speed records on electric motorcycles that he built in his workshop.
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