Transformers: season three powertrains

Spacesuit-Media-Dan Bathie-FIA-Formula-E-Hong-Kong-ePrix-October-2016-battery

Who is running what in season three? Current E technical editor Craig Scarborough summarises what we know so far.

Formula E’s third season arrives with few changes to the technical regulations and retains the Williams Advanced Engineering spec battery, which has given the sport’s constructor teams plenty of time to develop their powertrains. In some cases, the solutions making an appearance for season three have barely changed; in other cases, something there’s evidence of new thinking. That means there’s a good spread of evolutionary and revolutionary packages under the bodywork of the 20 cars being readied now on the streets of Hong Kong, which could make for a far tighter and more competitive field than ever before.

Spacesuit-Media-Nat-Twiss-FIA-Formula-E-Hong-Kong-ePrix-October-2016-Renault e.dams

Let’s talk about the tech. Renault took a bold step in season two with a high-tech powertrain featuring a Zytek motor mounted to a twin-speed gearbox wrapped up in a carbon fibre casing. The first gear was simply a starter gear, used to get off the line at lights out, and was operated with a manual gear lever. It was a package which simply ran away from the rest of the field. In season three, the gearbox has been removed, meaning the ZE16 motor now drives the differential directly with no need for any gearshifts. This change has shrunk the size of the rear and the carbon casing even further. Equally impressive is the lack of cooling required for the motor and inverter; the left-hand radiator, which cools the motor and inverter, is now just half the size of the standard part.

Also benefitting from this powertrain development is the reborn Aguri team, officially launched yesterday as Techeetah. Taking advantage of the price-capped customer supply of the ZE16 powertrain is a canny move, particularly as it was confirmed at the launch that Renault has supplied not just the hardware but the software too.

The ABT team was just a step behind Renault in season two and so not much has been changed there either. Once again, a Schaeffler motor drives a transverse gearbox with three gears. Unlike most other manufacturer powertrains this season, ABT continues to run a metal gearbox casing, rather than using carbon fibre. Cooling appears to still make use of a standard-sized radiator in the left sidepod, rather than a smaller unit, although the packaging of the motor, gearbox and inverter all inside the case still impresses.

Spacesuit-Media-Dan Bathie-FIA-Formula-E-Hong-Kong-ePrix-October-2016-DS Virgin Racing chassis

Perhaps the biggest swing in design this season is seen at DS Virgin Racing. Gone are the two heavy and energy-hungry pancake motors, replaced by a Renault-like solution. There’s a single motor driving through a gearbox to the differential. As with Renault, this, the inverter and the DCDC converter all sit inside a carbon casing. But, in DSVR’s set up, the powertrain is extracted through the open front of the carbon case, not requiring large openings in the side as on the Renault, making for a more efficient structure. Cooling is equally tidy with a radiator some two thirds of the size of the standard unit, but supplemented by a small additional unit fed by a separate duct. Uniquely, DSVR is not running the McLaren ECU, instead using Magnetti Marelli units.

Spacesuit-Media-Nat-Twiss-FIA-Formula-E-Hong-Kong-ePrix-October-2016-Mahindra Racing car

Mahindra has adopted Magnetti Marelli’s two-in-one six-phase motor. Here, the transverse motor drives a twin-speed gearbox attached to the differential. Also inside the carbon casing are the two inverters and the DCDC converter. Similarly to the DSVR package, the entire assembly is removed through the front of the carbon casing. Due to the efficiency of the Magnetti Marelli inverters, Mahindra has also downsized its cooling package, reducing aerodynamic drag caused by the radiator.

While awaiting its full Faraday Future powertrain (likely in season five), Dragon has essentially bought powertrains from Mahindra and renamed them. The team does look after its own software, however, aided by three Faraday staff at the team.

Having run a tweaked version of the season one powertrain in season two, Venturi has now adopted a transverse motor and gearbox/differential assembly within a carbon case. This uses a development of the first gen McLaren motor and a new format inverter. Despite this, cooling appears to be using the standard-sized radiator.

Spacesuit-Media-Nat-Twiss-FIA-Formula-E-Hong-Kong-ePrix-October-2016-MS Amlin Andretti garage

After its abortive season two powertrain development, Andretti has now arrived with its own powertrain. A Magnetti Marelli motor and inverter package similar to that of Mahindra is used, although here the motor sits longitudinally inside a carbon fibre bellhousing, driving a Hewland gearbox within a magnesium case. In this orientation there isn’t room for the (albeit small) pair of inverters, so Andretti stacks these above the battery where season one configurations located them, along with a DCDC converter to supply 12v power to the auxiliary systems.

NextEV adopted a direct-drive twin pancake-motor solution last season. This was compromised by heavy motors and twisting sub frames. Rather than bin the concept, as DSVR now has, NextEV has persisted with the concept. Grearbox specialist Omni Gear, which contributed in large part to Piquet’s season one title win, has worked closely with new company Magelec Propulsion (the companies have a shared founder) on the revised solution. There are still two axial flux motors present, now mounted transversely and driving a single gear in between them to the differential. All of this is contained in a slim carbon fibre casing, although the large inverter package has to sit above the battery.

Spacesuit-Media-Nat-Twiss-FIA-Formula-E-Hong-Kong-ePrix-October-2016-Jaguar Racing car delivery box

Arriving later than others to the development process for season three, Jaguar has still managed to create a bespoke powertrain, largely following the season one layout. Its motor sits longitudinally inside an aluminum case, driving a twin-speed gearbox to the differential. Above the battery is the carbon fibre-clad inverter. The team insists that it has no competitive advantage despite the powertrain being developed with Williams Advanced Engineering, which also designed and built the race batteries used by all Formula E cars. The team is two years behind the rest of the field when it comes to chassis data, team personnel point out. That might explain a more conservative drivetrain configuration for this year, although there are hints that something more radical is waiting in the wings, which could possibly see the light of day before season five.

Season three powertrain summary

Some teams persist with high levels of secrecy around their powertrains, despite all hardware having been homologated (which means no revisions can be made this season). Here’s what we’ve deduced thus far.

Team Motor Inverter Gears Casing
Renault Single transverse (Zytek) Inside gear case (Zytek) 1 Carbon fibre
ABT Single transverse (Schaeffler) Inside gear case (Schaeffler) 3 (transverse gearbox) Aluminium
DSVR Single transverse (unknown) Inside gear case (unknown) 2 (transverse gearbox) Carbon fibre
Mahindra Single transverse (Magneti Marelli) Inside gear case (Magneti Marelli) 2 (transverse gearbox) Carbon fibre
Venturi Single transverse (McLaren) Inside gear case (McLaren) 2 (transverse gearbox) Carbon fibre
Andretti Single longitudinal (Magneti Marelli) On top of battery (Magneti Marelli) 3 (longitudinal gearbox) Magnesium/Carbon fibre
NextEV Twin axial flux (Magelec) On top of battery (unknown) 1 Carbon fibre
Jaguar Single longitudinal (Jaguar) On top of battery (Jaguar) 2 (longitudinal gearbox) Aluminium
Techeetah As per Renault
Dragon As per Mahindra

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