This past September, at a race in Beijing, China, German driver Nick Heidfeld was coming up fast on leader Nicolas Prost of France. On the final lap, Heidfeld attempted a pass but clipped Prost’s car. Instantly, Heidfeld veered left, hit an embankment, and soared into the air. His car flipped and slammed into a shock-absorbing divider, shattering sections of the vehicle. Moments later, Heidfeld emerged unharmed. The two drivers were part of the first-ever Formula E event, a racing series featuring only electric cars. Although the accident was terrifying, it did help answer one of the questions about Formula E: whether its battery-powered vehicles can deliver the same serious thrills as other motor sports, like NASCAR or Formula 1 (F1).
The first Formula E season will feature nine races, including events in Miami, Florida, in March and Long Beach, California, in April (see map, below). The host cities determine the roughly 2-mile-long tracks, then clear the streets for the day. During the main event, the drivers will complete 32 laps of the course, cruising at speeds up to 225 kilometers (140 miles) per hour. Though the race lasts just one day, it took years of research and engineering to prepare the vehicles for these battery-powered sprints.
One of the main misconceptions about electric cars is that they’re slow. Ron Matthews, a professor of mechanical engineering at the University of Texas, explains that when compared with a traditional engine, the electric motor is actually better suited to acceleration—the change in velocity over time.
In a standard engine, a spark ignites the gasoline, and the energy from these small explosions drives mechanical rods called pistons up and down. Through a series of additional steps, the pistons eventually turn a cylindrical shaft. Their energy is converted into rotational energy, called torque, used to spin the car’s wheels.
With an electric motor, the transfer of energy is much simpler. There are no pistons: Magnets inside the motor spin a single shaft, which generates torque immediately. “Electric motors generate a whole lot of torque at low speed,” says Matthews. “That allows battery-powered cars to accelerate extremely well from a stop.”
Formula E vehicles can go from 0 to 97 km (60 mi) per hour in three seconds, only about one second slower than gas-fueled race cars. The reason an electric car accelerates a little more slowly than a gas-powered car is the battery, says Matthews. “Batteries are heavy,” he explains. The motor has to work harder to push that added weight, so the cars aren’t quite as fast off the starting line as the lighter, gas-powered vehicles.
Unlike F1 teams, which build customized cars to gain an edge over the competition, the drivers in the Formula E series all use the same vehicle, designed by the French company Spark Racing Technology. Théophile Gouzin, an engineer at Spark, says not only was the added weight of the batteries an obstacle during the design process, but their size was a problem too. “Fitting the battery case into the car was a real challenge,” Gouzin says.
The case holds 150 lithium-ion batteries—similar to those used in laptops. Combined, these batteries store as much energy as 10,000 standard AA batteries. But the battery pack takes up space that would normally be used for the structural, weight-bearing parts of the car—the equivalent of the beams in a building. So rather than adding parts around the battery case to support the car, designers made the case itself a structural piece of the car. “The vehicle is all designed around the battery,” says Gouzin.
PUSHING THE LIMITS
Spark designers also had to find ways to overcome various factors that affect the race car at high speeds. Aerodynamic drag—a force that acts on an object to slow it down as it moves through air—becomes more powerful as a car goes faster. The Formula E vehicles have curved bumpers that send airflow up and over the front tires. There are also miniature wings called winglets on either side of the driver’s seat that channel air over the car’s surface to reduce drag (see Inside the Formula E Race Car, right).
Another factor is centrifugal force, the same phenomenon that pushes you against the wall of the spinning Gravitron ride at amusement parks. When Formula E drivers speed around tight city corners, they have to balance their desire to go as fast as possible with the pull of centrifugal force. If they go too fast, the car could flip. Thankfully, the driver’s seat is very close to the ground. This gives the Spark a low center of gravity—the spot where the mass of the vehicle is focused—to help keep the car on the road, explains Matthews.
All these design choices helped make a fleet of extremely fast electric cars. Still, some racing fans aren’t sold on the new sport—which they say is too quiet. Spectators used to the roar of F1’s gasoline engines aren’t thrilled with the mellow purr of the electric motors.
Others argue that the Spark shouldn’t be compared to F1’s cars. The point of the series, they say, isn’t just the race. It’s also about pushing the technological limits of electric vehicles.
In fact, technological competition is going to become part of the sport in upcoming seasons. All drivers will still get behind the wheel of similar vehicles, but each team will be allowed to improve the battery system of its car. So in the years ahead, it may be that the car with the best battery wins. For now, though, it’s all about the drivers’ skills. The Spark might not be loud, but it still demands the talent of top racers. “Driving these cars through city centers is still a very difficult task,” says Gouzin.
Drivers use the steering wheel to change gears and to manage the car’s torque to conserve battery power.
To reduce drag, small aerodynamic wings channel air over the car’s surface, allowing air to rush behind the vehicle.
Instead of generating lift, like an airplane wing, the aerodynamic bumper channels air down so it presses the speeding car to the road.
The electric motor provides less than half the power of a traditional F1 engine, but that’s enough to accelerate the vehicle to speeds of 140 miles per hour.
The driver sits close to the ground, partly to reduce drag. Air flows around and over the driver instead of pushing into him or her, which would slow the car.
The three drivers who receive the most votes from fans prior to the race can activate a feature called FanBoost. This increases the motor’s horsepower by 20 percent for five seconds, allowing them to blow past their rivals—but drivers are allowed to use it only once per race.
The 150 lithium-ion cells in the battery pack last for roughly half the race. Recharging would take more than an hour, and the batteries are too hard to swap out because of the way their cases are built into the structure, so drivers switch to an identical fully charged car when power runs low.
Inside the battery pack, a liquid cooling system draws heat away from the electronics.
Grooved, all-weather tires maximize friction and increase the car’s grip on the road.