For Racing Glory, Students Built a Mountain-Busting Electric Motorcycle
Ohio State engineers optimized their bike for one thing: to climb Pikes Peak faster than any other bike, electric or gasoline powered
An hour before the qualifying round is no time to blow out the power inverter in your electric racing motorcycle.
It’s a Friday morning in June and easily the worst day of the year for a score of engineering students from Ohio State University, in Columbus. Months of painstaking labor have gone into their all-electric cycle, the Buckeye Current RW-3, to handle one race and one race only: the Pikes Peak International Hill Climb, a motorsports race up Colorado’s iconic mountain. It towers in the near distance; the students are at rock bottom.
In the past week, they’ve overcome adversities that include a burned-out noise maker (to alert pedestrians to the cycle’s silent approach), a wobbly seat, a cooling-system snafu, and a run-in or three with the powers that be. And now, a dead power inverter.
And yet, if panic is breaking out, there’s no sign of it. “This, too, is fun,” insists team leader Aaron Bonnell-Kangas, speaking somewhat less animatedly than he usually does.
Punching numbers on his smartphone, he tries to raise somebody—anybody—at Tritium, maker of the inverter, which turns a battery’s direct current into the alternating kind that the motor requires. Alas, it’s the wee hours of a Saturday morning at Tritium’s headquarters, outside Brisbane, Australia.
So everyone jumps. Off comes the bike’s seat, out come its electronic guts, on go the probes of the circuit testers. But the inverter’s troubles remain obscure. This isn’t a mechanical quirk in your father’s Ducati; this is a bug hiding somewhere among scores of chips and thousands of lines of code.
“It’s talking to us, but it’s not sending a signal to the motor,” says Polina Brodsky, a mechanical engineering student. “The computer is booting up, but it’s not doing anything.”
With just minutes left before the qualifying round is set to begin, Rob “The Bullet” Barber, the team’s pro driver, improvises a plan B. He hops onto a motorcycle belonging to one of the students—a gasoline-powered Kawasaki—and makes for the starting line. “Hope they [the race officials] count it, but it isn’t the team’s bike,” he frets.
The officials do count the bike. So now, all the team has to do is repair the inverter on the RW-3, run tests on a local track, charge each of the bike’s 938 A123 lithium-ion cells to capacity, roll the bike to the base of the mountain, and run the race. They’ve got 40 hours.
Student project though it is, the Buckeye Current is regarded as a serious contender. The team has gone far to optimize the bike to put out crazy levels of power, something it has to do for only the 10 minutes it should take to round the course’s 156 hairpin turns while skirting a skid into an abyss. Power is everything; energy storage, nothing. If the bike’s batteries die at the summit, the students will happily walk it down.
Sheer performance is no mere ornamental attribute but rather the heart of the surging appeal of the electric vehicle—the feature that shattered the golf-cart image. From zero to fabulous in 3 seconds, promises the dual-motor Ludicrous Speed mode in the Tesla Model S P90D. And, like the Buckeye Current, the Tesla does it all without a gearbox.
“This motorcycle is our idea of the perfect bike: powerful and nimble,” says Bonnell-Kangas, a grad student in electrical engineering. “We want to go up Pikes Peak ahead of the gasoline bike. We want to be the best.”
The race plays to the strengths of an electric drivetrain. First, an electric power plant offers instant-on torque, and that comes in handy on the course’s many switchbacks. Each one of them becomes a sort of mini drag race. Second, the EV will be indifferent to the thinning of the air as it makes its circuitous ascent—a rise of 1.4 kilometers (0.9 mile) over the 20-km course.
Why not use a compressor to load—or “supercharge”—the combustion chambers? “It’s hard to tune a supercharger because the air is so different at the base and the summit,” Brodsky explains.
This year’s iteration of the bike, the RW-3, uses the same frame as last year’s—a Honda sport model but minus the gearbox, engine, and fuel tank. In their place are the green mass of thumb-size batteries that cluster under the seat, all the way to the bottom. They weigh 80 kilograms (176 pounds), hold 7.7 kilowatt-hours—a quarter the capacity of the Nissan Leaf and about a tenth that of the Tesla Model S—and feed current through the Tritium inverter to an Enstroj Emrax motor, a 40-kilogram whirlwind rated at 100 kilowatts (134 horsepower). And the current comes with a lot of waste heat.
“There are two cooling loops for the motor and the inverter, each with its own radiator and pump—each part optimizes at different temperatures,” Bonnell-Kangas says. “A gas bike’s more efficient to cool because when you’re hotter, it’s easier to purge heat out,” typically through metal fins surrounding the cylinder chambers. “That’s why we need water cooling.”
The heat problems had actually started a couple of days earlier. After a time trial, Barber told the team that the engine had gotten a little hot. But the students couldn’t get the temperature data because the sensor, a thermistor, had been out of commission for some time. “It was down on our list of bugs, and other things were more important,” says Bonnell-Kangas, ruefully.
And putting sensors everywhere can increase the burden, adding more things that can go wrong. There are pressure gauges in the tires, flow gauges in the coolant pipes, voltmeters everywhere, all sending data to a central processor between test runs. That way, the team can fix glitches on the fly, a skill that comes in handy in a competition.
“We put a lot of effort into designing these electronic systems” to analyze data, says Sean Harrington, a team leader and an electrical engineering major. “We design with debugging in mind.”
He who errs last, loses. Here, in design methodology, trial and error is as important as theory, if not more so—a lesson you might not find in the standard engineering curriculum.
How much effort does this extracurricular activity consume? In some cases, more time than the coursework.
Aaronn Sergent, a mechanical engineering major, confesses to me that he puts in just 20 or 30 hours a week on the bike project. He’s almost apologetic as he tells me this outside Uncle Sam’s Pancake House, where the team has just breakfasted on eggs and pancakes. It’s 8:00 a.m, but the team started this day at 3:00 in the morning, doing time trials and tune-ups, well before the onslaught of summer tourists. Now, bellies full, these kids are about to go right into a second day of work back at their rented house in Colorado Springs.
Or even a third day, maybe. Bonnell-Kangas gets very little shut-eye: He texts me on the coming day’s plans well after I’ve fallen asleep, then does it again at 2:00 a.m., well before I wake up the next morning. Many hours later, as I stagger off to catch a ride to my hotel, I pass four of the students. It’s early afternoon, and they’re blowing off steam shooting hoops in the front yard.
Rest? Who needs rest?
The inverter problem defies an easy solution. The Buckeyes can’t buy an inverter locally, and they haven’t the time to airlift one in from the antipodes. So there the electrical subteam sits, hunched around the dining-room table of their rental house, tearing the broken inverter apart.
The Buckeye Current RW-3 gets its oomph from an Enstroj Emrax motor, which is rated at 100 kilowatts (134 horsepower). The motor is powered by 938 A123 lithium-ion cells, each about the size of a D battery. They weigh 80 kilograms and can store 7.7 kilowatt-hours—a quarter the capacity of a Nissan Leaf.
“The motor is synchronous, which means the inverter has to keep up,” Bonnell-Kangas tells me.
The rotor of a synchronous motor moves in lockstep with the rotating magnetic field. That field, in turn, is generated by output from the inverter, which varies in a repeating pattern, or cycle. The faster the motor turns, the more cycles the inverter must provide. But this inverter can crank out no more than 500 cycles per second—enough to turn the motor at 3,000 rpm. That’s the redline.
“So we designed a control system to keep the motor below that critical speed,” Bonnell-Kangas says.
This is why the inverter’s paralysis is such a big deal. As things now stand, the students can’t even get the motor to turn at all. And if they can’t fix it, then it’s good-bye to a year’s worth of dreams.
Just as I begin to head back to my hotel, the problem is apparently found: two very well-fried fuses in the power supply board. They got electrocuted earlier during a tune-up.
“We reversed the polarity [the direction of current],” Bonnell-Kangas tells me. “That burned the fuses, and that interrupted the power supply. We can fix this.” And they did.
It’s things like these that make you appreciate the sweat that goes into anything complicated: a motorcycle, a car, a jetliner. Fix one thing and you tee up another to fail.
Despite the frustrations, pressures, and compromises, they all can’t imagine doing anything else with their free time. When I ask Marc Ahlborg, an aerospace engineering major, why he chose this team rather than something more aeronautical (surely there’s a drone club?) he notes that he rides a bike himself, as do most team members. Though limited, the resources of this club are among the best at Ohio State, he adds. Most come as in-kind gifts from sponsors.
Take the 100-kW alternator that Cummins Generator Technologies provided to them gratis. The team had wanted a smaller one, but apparently Cummins doesn’t do small.
But the food bill comes out of the students’ pockets. So does the rent for the house, which they split evenly, and the transportation. Even bringing their own motorcycles out West is their own burden to bear: Ohio State has a rule against using school vehicles for private purposes. So while Buckeye Current and its appurtenances travel in a trailer worthy of a rock star, the personal gear mostly goes on the back of a pickup.
Even petty cash is scarce. When Brody Ringler, a mechanical engineer, argues that the team needs a $10 infrared thermometer gun to quickly check the tires and other parts, Bonnell-Kangas mulls it over for a good 3 seconds: “Okay, buy it.”
On Friday afternoon, when the students figure out the inverter’s problem and replace the blown fuses, I ask Bonnell-Kangas what he’d have done that morning if he’d gotten through to the Aussie company. Would he have maxed out his credit card to pay the AU $6,000 (US $4,592) for a new Tritium WaveSculptor200 inverter, plus the whatever-it-would-cost to fly it the 14,000 km from Australia to Colorado Springs?
“I’d have paid it,” he says.
Race day starts at the wretched hour of 1:30 a.m. Saying little, we drive in darkness, the mountain a huge black hulk in the distance.
Poking along the final stretch, we jostle along with vehicles from every category of racing—production cars, vintage cars, modified cars, dune buggies, trucks (even a semi), and of course, motorcycles of various weights, power sources, and designs. It’s a surreal outdoor museum of automotive oddities, “Jay Leno’s Garage” taking a run on the wild side. There are even low-riding buglike affairs with a sidecar, in which a passenger, called the monkey, kneels in order to hang off the side as a counterweight in a tight turn. (It’s a living.)
The team pitches a tent in the pit area, turns on the generator, powers up the fluorescent lights, puts the bike up on stilts, applies the blue Chicken Hawk electric tire warmers. They matter because the tires are racing slicks, so-called for their lack of treads, and they provide traction only when warm. They cool down fast in this chill air and on the frigid surfaces; all around, the mountain walls are pocked with snow.
While warming the tires, the team checks the bike’s major systems and tops off the charge in each of the myriad battery cells. You have to do that just so, filling up one battery to a certain point, then catching up the others, then doing it again. It’s the only way you can be sure not to overcharge any of them.
Well, that’s not quite true: You could design an automatic charging system, as the Victory Motorcycles team has no doubt done. They’re not far away, in the stretch that leads toward the burrito shack, and they are an actual company, based in Iowa. All they do is make motorcycles.
Hand charging is tedious. But then what would you do early on race day? The last few hours before the race seem to crawl, like in the old movies when the defense attorney and the defendant wait—and wait—as the jury deliberates. But for Barber, the guy whose life depends on sticking to that slick road surface, time is passing at a faster clip.
“It’s wet up there, really wet,” he says, returning from a little reconnaissance.
In another hour the sun would burn away that water, but the show must go on, and the electric motorcycles are the first category to climb the mountain. Barber thinks that sticking to the schedule is ridiculous: Surely, the famously waterproof gasoline-powered bikes should go first, he grouses. Surely, someone could go up there and sweep away the worst of the wetness. But there’s no time.
After some hurry-up-and-wait delays, Barber gets the go-ahead. He turns on the clanging noise maker, scoots off to the starting line, and promptly enters radio silence as the pit team unexpectedly loses contact with the bike’s transponder. Now the team must follow his progress fitfully, through a handful of visual sightings.
After an eternity, the news comes succinctly. “Our time is 11:16,” says Brodsky, her ear pressed to a phone.
No 10-minute race record this time, or victory of any kind. Ringler is plainly crushed. Brodsky says nothing. Bonnell-Kangas conceals his disappointment. This was his last hurrah as team leader; now he’ll take up his first job, a research position at the Detroit branch of Robert Bosch, the German auto supplier.
Hours later, after all the races are run and Barber can finally walk the bike down, he is ebullient. Or maybe he’s just glad to be alive.
“You guys were great,” he says. “It’s as good as last year’s time, and on a wet road. And the bike was great.”
He’s a pro. And so, literally, were the guys who won the category.
“The Victory bike was just so powerful,” Barber says later, while sitting on a couch back at the rented house. He was referring to an electric version of a bike made by Victory and ridden by Dan Canet. It posted a 10:17.8 time, about a minute faster than the Buckeye Current.
“I don’t know how they do it; Victory is very quiet about the design,” says Barber. When he isn’t racing, he works a day job in IT for Cisco Systems, in Manchester, England.
David did not beat Goliath, not this year. But maybe next year the team will build an automatic battery-charging system. Maybe they’ll revamp the power management system, inverter included. Or they could follow the lead of vehicle manufacturers worldwide and pare weight from the bike.
“I can’t say what we might do,” says Brodsky, diplomatically. “We’ll decide these things together, after looking at the data logs from today.”
Brodsky, alone among the students, was present at the creation. That was six years ago, when as a senior in high school she wangled her way into a new and decidedly bare-bones operation. Now she has graduated. Next year she’ll stay on as a grad student—on a mission.
“I’m the team leader next year,” she says. “The rest of the team voted me in.”