Formula E Prepares to Learn More Lessons for Season Two

The inaugural Formula E championship had a steep technology learning curve that continued throughout the season as the cars were put to the test on a wide variety of circuits, in varying temperatures. Now, they not only have to implement the lessons learned in time for the new season in October, but must deal with more engine makers as they try to make the powertrains as efficient as possible.

"With one season under their belts, the Formula E teams are investigating what they can do better for season two."

The idea behind Formula E goes back to 2012 when the FIA motor racing authority decided to have an all-electric equivalent to Formula One. The first season, which started in Beijing in September 2014, saw ten teams with two drivers each contesting the championship across ten cities. Each driver had two cars, meaning a total of 40 cars were needed. Nelson Piquet Junior became the first world champion after the final race at the Battersea Park Street Circuit in London in June 2015. Sponsored by Mouser Electronics, Piquet was driving for China Racing and clinched the championship by just one point.

Figure 1: Sponsored by Mouser Electronics, Piquet driving for China Racing clinched the championship by just one point.

Engine Technology

All the cars in the first season were built by Spark Racing Technology. The chassis of the Spark-Renault SRT 01E was designed by Dallara with an electric motor from McLaren. The battery system came from Williams Advanced Engineering and they used a Hewland five-speed gear box.

This, though, will all change for season two, which will run from October 2015 to June 2016 and again start in Beijing. Rather than just one powertrain manufacturer there will be eight who will build the electric motor, inverter, gearbox and cooling system, but the chassis and battery will be the same for all the cars.

Figure 2: Guests and Media inspect the show cars on display prior to the race.

Battery

The battery will again be built by Williams and Gary Ekerold, the program lead for Formula E at Williams Formula One, said when the engineers started last season they brought with them a lot of the lessons they had learned from Formula One with the kinetic energy recovery system (KERS).

"We developed a battery and KERS for Formula One, so we understood a lot of the technical challenges we faced with Formula E," he said. But that didn’t mean it was easy given the limited time they had to develop the battery system.

"We came to this quite late," said Ekerold. "We had to get the first prototype within six months. We took on this challenge. From a clean sheet of paper to having 50 batteries ready to go took about thirteen months. It was a challenge."

There was also very little flexibility when it came to space. The car had already been designed, so the space for the battery was fixed and the total weight of the cells could not be more then 200kg.

One of the big difficulties Williams faced with the battery was thermal management. This involved more than just keeping them cool; they have to be in a temperature operating window to get the best out of them, which sometimes meant warming them up as well as cooling them down.

"We invented an innovative thermal system for cooling," said Ekerold. "This was part of the battery management system – a mix of electronics and software – that we built. We already had developed a system for Formula One and we took that and developed it further for Formula E. This was both for technical performance and safety. We monitor the performance of each cell every second. We can’t reveal how many cells there are, but it is more than 150."

The first tests for the original season were held at the Donington Park racing circuit in England’s East Midlands and the batteries survived fault free for the 4500km of driving. After that, they were handed to the ten teams who then started to find issues that had not been previously detected, but changes were made and they were ready to go at the start of the season. Then came race conditions.

One of the big problems again was temperature as the cars had to operate in different climates around the world. The toughest proved to be Buenos Aires in January where the thermometer hit 36˚C. "That had an influence on cooling the batteries," said Ekerold. "We have had to do some work on that for season two."

Roadmap

Development work, though, does not end here. The FIA has a five-year roadmap in which new performance specifications will have to be met at different stages. From the start, the specifications were found not to match reality. The testing that was carried out at Donington Park, a professional racing circuit, did not transfer well to the actual racing conditions, which were on street circuits.

"They thus increased the performance specifications for the battery and they have requested these to be increased even further for the new season," said Ekerold. The original 133kW specification included 40kW for regenerative power. This was increased to 150kW with 100kW for regenerative power after the pre-season testing last year. This meant the average power went from 90kW to 120kW. For season two, the FIA has requested 170kW, but it is still undecided as to whether that will be achieved.

"We managed to meet last season's requirements," said Ekerold. "Logistically, we serviced 40 cars with only five spare batteries throughout the season. As to 170kW, we haven’t agreed to that. We have to look at how that will affect the performance of the battery. We are doing some studies of that at the moment."

Figure 3: China Racing’s Spark-Renault SRT_01E driven by team driver Nelson Piquet, Jr.

Preparing for Season Two

Last year, only one car failed on track during the whole season, a remarkable reliability record. Testing started in August 2015 at Donington Park for the new season. This brings with it new challenges for Williams because rather than having to work with just one engine partner they will have to work with eight. "We will have to integrate the battery with people who are all doing things slightly differently,” said Ekerold. “This is producing logistical and technical challenges."

One company that has decided to go its own way and build its own engine is Venturi Automobiles. Nicolas Mauduit, the team's chief technology officer, reflected on how it all went last season. "The main challenge for us as a new player in motorsport was to build a team," he said. "On technology, we have a strong background in powertrains, but we had to get to know the car. All the teams had the same car and it was like a black box to discover. We had to learn it component by component to see how we could use it. We had to understand this box that we hadn’t designed ourselves."

This made simulation an important element in the design process. Every component had to be modelled and the circuits had to be mapped. "In general, the races were pretty close to our simulation," said Mauduit. "What was different was the temperatures we had to face. For example, it was really hot in Buenos Aires. We had to manage and simulate how it was going to react in the hot areas and the rest." The other skill was finding a balance between energy and power. The cars could not race flat out all the time, so a strategy had to be developed with the drivers so that energy could be saved. This meant playing with the regenerative system when braking to make more energy available.

"We had to learn it component by component to see how we could use it. We had to understand this box that we hadn’t designed ourselves."

"On temperature, we discovered that if the driver was less aggressive on the throttle, we would heat the battery up less,” said Mauduit. “There is heat management round the battery but if we regenerate too much we can create heat around the battery which causes it to discharge less. We had to manage heat, energy, and power all at the same time."

With the relaxing of the regulations, Venturi decided to design its own powertrain for season two, which included the power electronics and rear suspension.

"We have had to put in a lot of effort for this to be efficient," said Mauduit. "If we are better in efficiency, we consume less and can be stronger in power. But we already have the fastest electric vehicle in the world."

He said just a one per cent difference in efficiency could make a big impact. Much of this effort has been in the power electronics and software to manage better what can be done with the motor and the battery. What is interesting is that whereas Williams sees it as a problem having a battery that links with eight different engines, Venturi sees having a fixed battery from a different angle.

"The battery will be the same for everyone," said Mauduit. "It will be the Williams battery and we are not allowed to modify it. We have to accept this is a fixed point that we have to design around. We have to live with the constraints of that."

The three components that he sees will have the most influence on performance next season are the driver, the organization of the team, and the set-up of the car. In these, the engineers can play with the mapping activities. These affect the way the driver interacts with the car, how the driver brakes and uses the regenerative system. "We are putting a lot of effort into the mapping activities because it is really important," said Mauduit.

Figure 4:2014 FIA Formula E, Beijing China

Future

After a successful first season for the Formula E championship, the FIA is relaxing the rules to allow the engineers to be more innovative in the car design. This is almost the opposite of what is happening in Formula One, where each year the regulations on what the teams can and cannot do increases, reducing their ability to do something different. This has been much criticised by both fans and the teams, and many believe that the more casual attitude in Formula E is a test bed for what could happen in a future Formula One season.

Whereas innovations in the first season of Formula E were mostly limited to the powertrain, now the engineers can play with the design of the motor, inverter, gearbox and cooling system. What remains fixed is the chassis as the FIA do not want teams throwing money at aerodynamic improvements; the ruling body is also well aware of one of the problems in Formula One where the big spenders do better; part of the reason for its limits on innovation.

Also, as discussed, the battery is a fixed element, and though Williams is working hard to make it even better, the same battery design will be in place for all the teams and they will have to design around that.

However, in the FIA's roadmap is a further relaxation, probably for the third season, that will allow teams to do more regarding battery design, and this may lead to competitive manufacturers entering the arena.

Thus, from an engineering point of view, Formula E is an exciting addition to the motor racing world. Designing the cars has forced engineers to be more innovative and with the FIA relaxing rules as it goes along, such innovations are likely to continue. The result is an exciting racing environment on street circuits combined with engineers pushing technology to new limits. What more could we want?

Steve Rogerson, a contributing writer for Mouser Electronics, is a freelance journalist specializing in technology subjects, mainly in electronics and communications, as well as other engineering and technology areas. He also writes about sport and beer. His current work includes editing Vehicle Electronics, a monthly magazine and web site.