To change the deeply ingrained prejudices about electric vehicles, Formula E called in the best in the field, including former Formula One champion Williams, to build a fully-fledged all-electric racing car in just two years. And building the car's battery was one of the biggest challenges.
Backed by such automotive engineering heavy weights as McLaren and Williams, the Formula E project partners managed to develop from scratch and in only two years an all-electric racing car capable of going around a circuit for 30 minutes at 250 km/h and accelerating from 0 to 100 km/h in just three seconds.
Williams, the designer of the racing car’s 300kg battery (safety case included) was among the last to join the venture, barely 15 months before the series’ opening, after the original battery supplier backed off.
“It was particularly challenging for two reasons. First was the timeline which was very aggressive. We had a very short period of time to develop a working prototype and carry that through into full scale manufacturing of 45 units,” says Doug Campling, technical lead at Williams Advanced Engineering and one of the principal designers behind the battery system. “Also challenging was the packaging environment presented to us. We were effectively told the volume that the battery had to go into, which, had we been involved early on, we would have probably asked for a few changes.”
However, true to its reputation, Williams took the fast-track project successfully to the finishing line just in time for the first Formula E test events. Though starting from scratch, there was a wealth of technical knowledge to draw from.
Battery with brain
“Williams has been designing its own Kinetic Energy Recovery System (KERS) for its Formula One racing cars for the last two or three years plus we have also done work on things like the Jaguar’s CX75 hypercar,” said Williams’ battery engineering team leader Gareth Yorke, pointing to the hybrid-electric two-seater concept introduced at the 2010 Paris Motor Show. “Williams designing and developing a battery for Formula E is very much building on that experience and constantly improving the way we build things.”
Watch a video from our visit to Williams Advanced Engineering
The 28kw/h lithium ion battery features a smart management system, which is a direct evolution of technology originally developed for Formula One and later used in the Jaguar CX75 supercar.
“The specific thing we have done with this battery is that we have a master control system that looks at the voltage and the temperature of every single cell that we have in there,” Yorke explains. “And what that’s doing is that it’s constantly monitoring the battery to see if there is anything unusual happening and the battery master system, the brain of the battery, has the chance then to manage that, to shut the battery down, to limit the power, etc.”
“The materials we use are specifically selected for their mechanical and thermal properties because thermal management of the battery is extremely important. Because this is a racing application, we are constantly looking and evaluating whether we can use lighter materials to reduce the overall weight.”
Due to the inherently hazardous nature of car racing and the infamous tendency of lithium ion cells to ignition, the whole battery has to be as carefully protected inside the car as the drivers themselves. Williams thus had to crash test the battery for all types of impacts to make sure everything stays in place even in the most extreme circumstances.
“We were the first company that did a successful FIA-controlled crash test on a battery. We did tests for all types of impacts - front, back and the side impacts as well,” Yorke says.
In the case of conventional electric vehicle batteries, range is the number one issue. Formula E’s racing batteries are allowed to run out of juice after only 30 minutes of aggressive driving and will face its very own set of challenges.
“If you are designing a racing car battery, you are limited on space and you are limited on weight,” says Doug Campling. “We had to consider these factors very carefully in our design and that brought some specific challenges for overall robustness. It’s no different from Formula One and a race engine. You want to make it as light as you possibly can, which is prone to reliability issues, which you wouldn’t see in a road car. That’s the same for Formula E, it’s a race battery, it’s not a battery for a road car.”
The batteries are required to achieve consistent output not only across teams but also over a two year period for which the first batch of Formula E cars will be used. Total usable energy, which can be drawn from the battery pack, is 28 kWh.
During the first season of the FIA all electric Formula E Championship, all teams are competing with identical cars built by Spark Racing Technology and equipped with Williams-supplied batteries, Dallara-developed chassis, an electrical engine built by MacLaren and Hewland’s five-speed gearbox.
Limitations of the battery technology have been the major driver for how FIA shaped the first season’s regulations. Unlike in Formula One, each driver competing in Formula E will have two vehicles, swapping them mid-race when the first one depletes its battery.
Swapping cars was preferred by FIA when laying down the rules as changing the securely mounted batteries would be too risky. Charging was out of question, as it would disrupt the race for at least an hour.
The true excitement, at least for the technology enthusiasts, will probably start with the second season when the constructor’s championship will begin. With the ambitious goal to show the world that electric vehicles can be exciting and fast, Formula E hopes to push electric vehicle technology to a new era, with the foremost focus, of course, on the electrical power train and battery technology.
Williams, though not having its own team in the competition, hopes to stay involved and explore the limits of the technology it has developed.
“The FIA states the maximum weight of the battery cells that we can use. But even with that restriction we still think it is possible to make some improvements to the battery that we have today,” says Doug Campling. “Now that we have actually seen how the battery is used in the car, we will certainly be interested in developing batteries with some partners of the series.”
Gareth Yorke expects that improvements in battery chemistry will lead to increasing capacity of Formula E batteries over the next years.
“A lot of this is actually driven by the companies that are working in battery cells themselves. Many companies including our partners are looking at reducing the size of the batteries but maintaining or increasing the power density,” says Yorke.
“So whereas I expect to see batteries getting smaller and smaller, I expect from racing applications that they will just want more and more power and more range. I don’t expect that the cars would change from the battery size point of view.”
Expected to always stay in parallel with its more established and high-profile counterpart Formula One, Formula E doesn’t aim to convert the traditional petrol-loving motor racing audiences. Instead, it wants to attract younger, environmentally conscious public. With all its races being held on completely new city circuits, the message is clearly directed to inspire city dwellers to make their next new car an electric one.
“Electric vehicle technology is a fact of life, it’s here, it’s not a gimmick, electric vehicles are here and they are here to stay,” says Doug Campling, who admits that his heart truly is still in the combustion engine technology as perfected by years of development.
“It will be interesting to see whether Formula E ever deviates away from the conventional single seater layout, to something that is more akin to perhaps how electric vehicles for the road might develop. One can think of how they might use regenerative breaking on the front axle as opposed to just the rear axle and perhaps changing the aerodynamics in the way it is more applicable to an electric vehicle.”