In a slender, bullet-shaped car, the University of Michigan Solar Car Team will soon race down the Australian outback in the Bridgestone World Solar Challenge. The team is counting on its new battery system and solar cells to propel it to a first-place finish.
The multiday, 1,800-mile competition starts at 8:30 a.m. Oct. 13 in Darwin in Australia’s Northern Territory. That’s 7 p.m. EDT Oct. 12 in the United States. The team will drive against more than 40 cars from around the world as they travel to Adelaide, South Australia.
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“This close to the race there really isn’t an emotion you don’t feel,” said Juliette Shaheen, a computer science undergraduate and the team’s weather strategist. “We built this car. And we’re about to race it through the Australian Outback, so it really doesn’t get much better than that.”
This year’s vehicle, Electrum, might look like the one that raced at the last world challenge, but under the hood are significant changes.
In a complete electrical system overhaul, the team ditched traditional lithium ion batteries and switched to lithium polymer cells. They’re seeing double-digit boosts to power efficiency, while cutting down weight per cell. This is crucial because race rules dictate the total weight of batteries on board. The team expects its competition to still be using lithium ion.
The new batteries were first scoped out by Daniel Kohler, a computer science senior and the team’s high-voltage lead, when he joined in winter 2018. At the time, he was blown away by their specs.
“When I ran the numbers during research, the new batteries came up with double-digit efficiency improvements over what we had been using. When I told the team originally, they couldn’t believe it,” Kohler said.
They ordered some samples for testing and turned to Jason Siegel, an assistant research scientist in mechanical engineering at U-M who specializes in lithium batteries. With Siegel’s mentorship, the team put the new batteries through their paces. To Kohler’s surprise, the numbers were legitimate. The students had found their most innovative addition to Electrum.
“The team has done a good job of characterizing the cells and usage pattern over the race to design a pack with minimum weight that will safely operate over the race parameters,” Siegel said. “It was fun to work with such an energetic and committed team of students.”
With the electrical system overhaul and tuned-up aerodynamics, the team members believe they’ll be able to go faster than ever at the Bridgestone World Solar Challenge, beating their 2017 second-place finish — a best-ever result for U-M.
The race ends in Adelaide, South Australia. While it’s officially over Oct. 20, the U-M team typically finishes in four or five days.
Electrum is the 15th car made by Michigan Solar since being founded in 1989. The team has won the American Solar Challenge nine times, had podium finishes in the Bridgestone World Solar Challenge six times, and won its first international championship in 2015 at the Abu Dhabi Solar Challenge. With more than 100 students from schools and colleges across the university, it’s one of the largest student organizations on campus.
“Given the long hours we’ve been pulling to make a competitive, top-tier solar car, and considering the fact that — unlike many other top teams — we’re all undergraduates that were taking classes through the start of the summer, I’m impressed that our character and strong work ethic can bring us all together when this should be, by all rights, an extremely tenuous relationship,” said Ian Stewart, an electrical engineering sophomore who serves as the race microsystems engineer.
“All of us feel the stress of competing on the world stage, but we’re using it to band together.”