In Formula E, all teams compete with a standard chassis. With the start of the 2022/23 season, the "Formula E Gen3" replaced the "FE18 Spark Racing Technology", better known as "Gen2", used in the previous four years. After the Formula E cars took to the track with identical drive trains in the first year, since the second championship year 2015/16, in-house development of the electric motor, inverter, gearbox, rear suspension and software has been permitted for registered manufacturers. Currently, six out of eleven teams compete with a specially designed drivetrain.
The Formula E battery is also a standardized component, supplied by Williams Advanced Engineering. The accumulator stores the energy, of which up to 40 kWh is available to the drivers in the race.
As the series' official tyre supplier, Hankook has been contributing treaded 18-inch all-weather tyres that are designed for sustainability and are also partly made from sustainable materials since 2023. As a rule, the tyres will survive an entire race day. All details can be found further down on this page.
The lithium-ion battery from Williams Advanced Engineering (WAE) weighs around 284 kilograms and is located in the rear of the car and can store up to 51 kWh of energy. However, a certain amount of energy is intended for the "zero laps" before and after the race (known as outlap & inlap) and as an emergency reserve, which is why the drivers actually only have 40 kWh available during the race. This corresponds to the capacity of around 500 laptops or 6,500 smartphone batteries.
In seasons 1 to 4 (2014 to 2018), Formula E already relied on a unit battery from Williams Advanced Engineering (WAE) with 28 kWh of usable energy. This, however, this did not provide enough energy for a full race distance. Therefore, towards the middle of the race, drivers had to switch to a second car with a fully charged battery after just over 20 minutes. With the introduction of the second generation of cars at the start of the 2018/19 season, which had a battery from McLaren Advanced Technologies (MAT), these pit stops became obsolete. The drivers had 52 kWh of energy at their disposal. However, this battery was more than 100 kg heavier than its successor.
Since the battery operates in a comparatively small temperature window, it has to be cooled constantly. In racing trim, the airstream is sufficient for this. In the garage, however, the mechanics have to install air pumps and containers with dry ice in front of the side box. The radiator in the right-hand side box cools the battery, its counterpart on the left-hand side the electric motor.
Motor, Transmission & Inverter
The drivetrain - consisting of the motor, gearbox, and inverter - is the only area of the Formula E car in which manufacturers are allowed to develop freely, alongside the rear suspension and software.
While the battery can only output direct current, the mostly three-phase AC electric motors require a very precisely frequency-tuned alternating current input to convert the available energy into power and transmit it to the drive axle through the gearbox. The manufacturers are allowed to determine the number of gears themselves. The inverter is responsible for converting the energy and creating this voltage profile as the centerpiece between the battery and electric motor.
The driver can choose from various power settings via a rotary control on the steering wheel. For example, there are settings for the shakedown (max. 130 kW), qualifying (max. 350 kW), the race (max. 300 kW - formerly 220), or the attack mode (350 kW - formerly 235).
During recuperation, the energy recovery during "coasting" and braking, the drivetrain can operate in the opposite direction: Drive axle >>> motor >>> inverter >>> battery. Up to 600 kW can be recuperated (350 kW on the rear axle, 250 with the standardized front motor). The recovery process in the braking zones through "lift and coast" is one of the most complex tasks for drivers during a Formula E race, although they have been supported by the vehicle's software since 2018 with the "brake-by-wire" system. With good recuperation work during the race, a driver can extend the range of their battery by almost 20 percent.
Aerodynamics in Formula E
In Formula E, proprietary aerodynamic developments are strictly prohibited with regards to cost control. Teams can only adjust the angles of the standardized front wing flaps to adjust the car's downforce for high (qualifying) or low (race) grip levels. The large diffuser at the lower rear end, which generates a negative pressure (Venturi effect) and effectively sucks the car onto the track, has the greatest impact on aerodynamics.
Tyres in Formula E
The official tyre partner of Formula E since the 2023 season is the South Korean company Hankook. Each driver is provided with two fresh sets of tyres for a race weekend, with which the drivers have to manage in all sessions. In the case of a "double header", drivers receive an additional set of tyres for the weekend.
The 18-inch Formula E tyres are used in both dry and wet conditions. The main focus for the electric series and Hankook is on the durability and series-production value of the tyres.
A special feature of the Hankook tyre is the rubber compounds used: For example, the tread consists of two different types of rubber, one of which is found on the inside and the other on the outside. The intended goal of this construction is to optimize grip on both dry and wet roads.
Between 2014 and 2022, Michelin supplied all teams with bespoke 18-inch all-weather tyres.
Development Freeze & Homologation
With the exception of the powertrain (motor, gearbox, inverter, and rear suspension) and the control electronics, there is a general development ban in Formula E. For cost reasons, no work can be done on any other vehicle parts in the foreseeable future.
A few months before the start of a new season, the powertrains are homologated by the FIA. Once a manufacturer passes the mandatory crash tests, which must meet the standards of Formula 1, they may no longer make any changes to the hardware of the vehicles. Only software adaptations are still possible afterwards. The software is continuously developed throughout the season.
In order to save costs, all powertrains are homologated on a two-season cycle in Formula E. Manufacturers will thus have to use the same hardware in the 2023 and 2024 seasons.
The SRT_01E was the Formula E car of the "first generation" and was used in the electric series for four seasons between 2014 and 2018. In the rear of the race car, which visually resembled other formula racing series, a battery from Williams Advanced Engineering (WAE) supplied the electric motors with 28 kWh of usable energy. This amount of energy was sufficient for a stint of around 20 minutes, which necessitated a vehicle change around the middle of the race.
In the first season, the drivetrain (motor, gearbox, inverter) was also a standard component - all teams thus used identical cars. However, from the end of 2015, the Formula E allowed registered manufacturers to design their own drivetrains. As a result, most racing teams have been using their own drivetrains in Formula E since then. Only the teams Aguri and Andretti initially remained with the standard drive unit with the electric motor from McLaren and five-speed gearbox.
During the first generation of Formula E, the FIA repeatedly made adjustments to the rules of the electric series. For example, it increased the maximum power in race mode from 150 to 180 kW, increased the maximum recuperation from 100 to 150 kW, and refreshed the look of the SRT_01E with a new upper front wing plate for the third season.
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