Group testing of the production cars supplied by SRT and known as the SRT_01E Formula E car was earmarked for July and August at Donington Park. But before that SRT along with McLaren and Williams Advanced Engineering technicians descended upon several low-key French and Spanish test facilities to undertake a reliability and development phase.
The first ever test run took place at the La Ferte Gaucher facility in central France. This was preferred by ART GP and as a result SRT used it extensively, so on 13 November at approximately 10.13 local time, Lucas di Grassi accelerated away from the pit-lane and on to the track for the first of 40 laps that were completed that day.
‘It felt like a big moment when it was happening,’ says Di Grassi, who went on to publicly debut the car at a Las Vegas demo in January 2014. ‘The collective positive feeling was there and it was a time I will always remember even though it was so cold in the middle of nowhere.’
The engineers’ lonely days of testing continued through the winter months and by the spring a rota of test drivers were getting miles in the new prototype. Jonathan Cochet, Nyck de Vries, Ho-Pin Tung, Antoine Leclerc, Emmanuel Collard, Adrien Tambay, Frederic Makowiecki, the late Anthoine Hubert and of course Di Grassi all pounded around tracks such as Le Luc in France and the Monteblanco, Calafat and Ascari facilities in Spain.
After the Vegas run, the spring of 2014 saw major tests carried out at Monteblanco and Le Luc. By April the group test dates of 3-4 July and 9-10 July were announced for Donington Park.
The early testing of the SRT_01E at the end of 2013 and early 2014 did not use the final WAE designed and provided battery. Instead a temporary unit was utilised as the final installation and testing of the bespoke RESS was undertaken.
The principles of the electric propulsion system as a package was quite simple. The battery, known in motorsport as the Rechargeable Energy Storage System (RESS) is a store for the usable energy, the equivalent to a regular fuel tank in a traditional internal combustion-engined (ICE) powered car.
The requirement to use a standardised battery, developed by WAE, so a unit comprised of lithium ion cells and weighing in at 350kgs.
The maximum amount of energy teams were allowed to use in the first season was 28kWh. This was ultimately transmitted to TV viewers as a battery percentage and illustrated how efficient or not the drivers were in using their set energy.
The cars were regulated to how much power they could apply during both qualifying and the race. A 200kw maximum in qualifying was allowed while the race itself saw a restriction of 150kw of power output.
The length of time that the battery would last depended mostly on how hard the driver pushed it over the duration of the race, but usually it would be around the 25 and 30 minute mark. Drivers had to complete a pit stop during the event to change their car for a new charged package.
The Tech Choices
The other crucial components in the overall electric powertrain was the motor itself and also the inverter. The inverter is formed of several extremely high powered switches that enable power to the motor. It is this management of the current which in turn produces the immediate power and torque which enables drive itself.
The season one motor provided by McLaren was itself made up of two parts. These were a rotor which drives the driveshaft and a stator which contains the rotor and stays stationary.
The motor casing protected the rotor which incorporated magnets and the stator is wrapped in copper wire coil-like assemblies. The current from the RESS goes through the inverter and is sent to the motor. This stimulates a magnetic field as it passes through the coils of the stator.
The rotor’s magnets are then attracted and resisted by the stator’s magnetic field which then causes a spinning of the rotor within the housing of the motor itself. Thus the car’s power is created with up to 20,000rpm of motor spin. This is approximately 2,000 more rpm than a typical F1 hybrid engine.
The original season one powertrain was controlled via regular gears, with the maximum motor speed and the number of motors in the car ultimately determining how many gears the transmission needs. In this case it was a reasonably traditional 5-speed gearbox provided by industry leaders Hewland for the first season of 2014/15.
The championship mandated, as part of its future rules ‘roadmap’, an open powertrain iteration of regulations for the second season which would begin at the end of 2015. Several teams, such as NEXTEV and DS Virgin Racing opted for a twin-motor designs which were allowed until season six (2019-20).
From the drivers point of view, handling a fully electric powertrain compared to a regular ICE powered car took some getting used to.
‘When I drove the car for the first time, I thought ‘this can be good racing,’ remembers season two champion Sebastien Buemi.
‘Initially I felt it was going to be like an underpowered Formula 3. But in the end, the car had not much grip, and it was hard to drive, so even though on paper the power was low, it didn’t feel like a slow car, just because the grip was very limited. I thought in city centres, it’s going to be quite exciting and it really was.’
The expediated nature of the testing phase meant there were few home comforts for drivers too, something which Antonio Felix da Costa, who’s Formula E career went full circle from a nascent Amlin Aguri squad in 2014 to the DS Techeetah team in 2019, remembers.
‘I turned up to Donington and there were two spanners on the floor, the radios are not working and it is chaos,’ recalls da Costa. ‘I was testing with another driver (Kevin Korjus) and I was faster than him but I tell you I actually hated it because the team was a mess and the car was quite tricky to drive.
‘The problem was mostly with me because I was coming from the DTM and it all seemed quite unprofessional, so I called Tiago (his manager – Tiago Monteiro) and said ‘get me out of this contract.’
After an intervention by Da Costa’s then BMW DTM boss, Jens Marquardt, da Costa’s extrication from the deal was halted. This was both an indication of BMW’s future planning and also a fortunate turn of events for Da Costa who became one of the stars of the series.
