The fully-electric next generation car to be used in FIA’s 2018–19 Formula E Street Racing Championship shows a strikingly futuristic new design.
By Murray Slovick, Contributing Technical Editor
Back in the 1950s, the association between winning stock car races on Sunday and selling that brand’s cars in showrooms on Monday was an accepted fact. And while car racing now has less of an effect on the general car shopper (owing to the decreased relevance of race cars to today’s average road vehicle), racing still represents an important experimental platform for technology development.
As such, when big changes are afoot regarding the design of racers—the new Formula E car, for example, demonstrates a step-up in performance from the current electric iteration with almost double the energy storage capacity and double the range—those involved in disciplines ranging from battery technology to drive motors to inverters can be counted on to pay close attention.
Formula E is currently in the midst of its fourth season competing on unique city street race circuits in New York, Paris, Hong Kong, and other cities. Last week, along with its governing body the Fédération Internationale de l’Automobile (FIA), it released the first digital images (Fig. 1) and some specifics about of the fully-electric Gen2 car that will be used for its next three seasons, starting in Season 5 (2018-9).
Thanks to the relatively small 28-kWh battery they use, the current cars of Formula E only run for about 20-30 minutes out of each 50-minute race. So today’s Formula E races require two identical, fully prepped vehicles—both with fully charged 28-kWh battery packs—to finish the race, with every driver performing a mid-race pit stop to switch to the fully charged car. Tire changes, unless caused by a puncture or other damage, are not permitted during this pit stop phase.
The idea of swapping high-voltage components such as the battery pack was initially considered, but rejected as too risky given the possibility of mistakes that could be made during high-pressure moments in the middle of a race. In the end, organizers opted for full car swaps.
As of Season 5 this will not be necessary. In a three way collaboration, McLaren Applied Technologies, Lucid Motors, and Sony will provide battery packs meeting the new Formula E specification calling for a battery weight of 250 kg (551 lb.), 54-kWh energy, and peak power of up to 250-kW—or 50-kW more than the current car, and roughly the equivalent of 335 horsepower. The new 54-kW battery pack also has to be capable of being fully charged in 45 minutes using 350-kW ultrafast charging and racing-speed energy recovery under braking.
With the move to a larger 54-kWh pack, there will be more room for strategizing and managing the energy flow from lap to lap. Even though each driver will spend countless hours in a driving simulator, the number of variables involved—in particular trying to get around a competitor or, alternately, fending off charging drivers trying to improve their race position—will mean that the race still will be won not by driving at ten-tenths throughout, but by means of careful power management (i.e., how much energy a driver uses per lap).
Power this year (Season 4) is limited to 200-kW for qualifying and 180-kW for the race itself (10 kW more than Season 3) with additional energy for the winners of the FANBOOST vote. FANBOOST is a fan interaction system where fans vote to give a driver an extra energy boost during the race, to be used for making a passing move or holding off an attempt to overtake. The voting window opens five days before the event. Fans can vote once per day on each eligible platform, either via social media or the official Formula E website. Voting closes six minutes into the race, with the top three drivers with the highest percentage of votes receiving an additional 100-kJ of energy in their second car only.
The Spark-Renault SRT_01E chassis, which has been used by the championship since its inaugural season, will be replaced by a brand-new chassis once again designed by Spark Racing Technology and called the SRT05e. Much of the Gen 2 body and all of the chassis will remain carbon fiber. The cars will have an overall maximum length of 196.9 in. and an overall maximum width of 70.9 in.
Compared to their hydrocarbon-fueled Formula 1 (F1) cousins (the racers that dash down the streets of Monaco) Formula E cars will weigh several hundred pounds more because of their now-heavier battery packs. Season 5’s Formula E racers will tip the scales at roughly 1,950 lb. while the overall minimum weight of F1 cars has gone up by 6 kg to 734 kg (approximately 1,618 lb.) for 2018. By comparison, the Gen 1 E-cars weighed about 1760 lb.
Even given the weight gain, the cars are expected to accelerate quicker and top out at higher speeds.
At least one team, the Venturi Formula E team, is racing this year with full SiC power modules forming the basis of its inverter (Fig. 2). Supplied by Rohm, the full SiC power module is 43% smaller and 6 kg lighter than the inverter for Season 2 and 30% smaller and 4kg lighter than that used in Season 3. In all, nine different manufacturers are creating powertrains for the 2016-17 season. Rohm provided SiC- Schottky Barrier Diodes (SBDs) in Season 3 (2016-2017), but this year its full SiC power modules combines SiC SBD and SiC MOSFET components. This contributes to energy efficiency, having more compact peripheral components throughout the high-frequency drive, reducing switching losses, and contributing to a more compact cooling system
Debut of the Halo
Looking at the side profile of the racers, it is evident that the new Gen2 car uses what’s known as a “halo,” a cockpit head protection device designed to further improve driver safety in the event of an accident, and in particular to deflect debris away from the driver’s head (Fig. 3). The Halo will be introduced on the chassis to meet FIA rules that a Halo must be involved in all single seater series (including Formula 1) by 2020.
With all-electric-powered race cars, Formula E racers are devoid of the deafening engine roar (80 or more decibels) and the trailing smoke enthusiasts have come to associate with F1, IndyCar, or NASCAR motorsports. But it is this environmental friendliness that has allowed organizers to receive permission to race on the streets of metropolises such as Hong Kong, Paris, or New York while championing a clean environmental approach that does not involve fossil fuels.
If you’d like to be a principal of a Formula E racing team, know that FIA has set the total cost of a “ready-to-race” Gen2 Formula E car at a maximum of €817,300 (about $1.013 million). The powertrain is capped at €250,000 ($310,000), the Halo device at €12,700 ($15,755), the chassis at €299,600 ($371,626), and the battery pack at €200,000 ($248,066).
A Season 4 (2017-18) car will set you back €480,000 ($595,377), or about $400,000 less than a Season 5 car, but consider that you have to prepare two cars for each race this year and only one car per race next year.
Season 5 is looking like a good one for Formula E. The series will have factory-backed entries from Audi, BMW, Mercedes, Jaguar, and Porsche, plus enhanced technical capabilities.
Formula E says more details will be revealed about its Gen2 car when it makes its in-person debut at the Geneva Motor Show in March.