"A Battery is Like a Living Object - It Remembers What You've Done"
Race Tech magazine
"A Battery is Like A Living Object - It Remembers What You've Done."
With battery technology key to the seismic shift towards electrification, Chris Pickering talks to the US CEO of a battery pioneer that deals with some of the world’s most demanding customers.
Cast your mind back to 2012. Lewis Hamilton was already a World Champion with five seasons of Formula 1 under his belt, Toyota was back at Le Mans and the FIA had just announced its plans to launch an all-electric race series called Formula E. In that context, nine years really doesn’t seem like a very long time.
Why nine years? Well, that’s how long those of us in the UK have until the sale of conventional petrol and diesel road cars will be banned. Hybrids will continue to soldier on in some form until 2035, but even their days are numbered. Suddenly the mass-adoption of electric vehicles – for so long a mirage on the horizon – seems very real and very close.
Admittedly, that’s just one market in a vast global industry, and there’s some debate as to whether this highly ambitious target will actually be met. But it’s indicative of a seismic shift towards electrification in road cars, which will have to be reflected in motorsport if we want the sponsorship dollars to keep rolling in.
By far the most challenging aspect of an electric vehicle to engineer is its battery. Electric motors are cheap, light and based on well-proven technology. High power, high energy batteries, on the other hand, are an emerging technology that will decide the success or failure of electric motorsport in the coming years.
One of the pioneers in this arena is Saft, a wholly-owned subsidiary of Total. Headquartered in Paris, with R&D centres in France and the United States, it was one of the first battery suppliers to work on F1 KERS systems – establishing partnerships that endure to this day.
“Our activity in F1 started back in 2006 with sampling high power cells for evaluation, we manufactured the first production cells in 2008 and raced for the first time in 2009,” recalls Annie Sennet, CEO of Saft America and executive vice president of the company's Space and Defense division.
“Lithium ion batteries were still relatively new at that time and Saft was known to be one of the leaders in high power applications, so an F1 team approached our R&D centre in Bordeaux. Our colleagues there referred it over to us here in the United States where we were working on high power projects for the US Department of Defense.”
The brief was basically to provide very high power from a small, rechargeable cell. The closest thing that Saft had on its shelves at the time was a battery system used on the F-35 Joint Strike Fighter, so this was taken as a starting point and tailored to the F1 requirements.
One of the eventual defining requirements was that the cells had to operate at unusually high temperatures in order to minimize the heat removal requirements of the cooling system. Over the years, Saft has been able to progressively push the maximum operating temperatures up further still, enabling teams to minimise the impact to aerodynamic performance that would otherwise be required from a larger radiator for the cooling system.
“In the defence world, everyone wants things that can work at low temperatures, the same for aerospace. For motorsport, we suddenly had a lot people coming to us and saying ‘how hot can you go?’” comments Sennet. “The other big difference is the timescale. With the Department of Defence you might get five years to do it; with Formula 1 it might be six months.”
Much like internal combustion engines, batteries have a sweet spot where they operate best. Higher temperatures can actually boost performance, but the challenge then becomes durability.
“Developing an electrochemistry that could operate and also be recharged at very high temperatures was a really big leap in technology. It relates a lot to the thickness of the electrode and the electrolyte formulation,” Sennet explains.
This comes down to the fundamentals of battery chemistry. A voltaic cell works by allowing electrons to flow from one electrode material to another via an external circuit, thus producing a current. To balance out the flow of negatively-charged electrons, positive ions (liberated at one electrode and absorbed at another) must flow through the electrolyte within the cell. The composition of this material is key to the lithium ions’ ability to move back and forth within the cell, and it can degrade over time.
“These electrolytes are organic, so they tend to degrade faster at higher temperatures. It’s like leaving an apple out in the sunshine as opposed to putting it in the fridge,” notes Sennet.
Formula 1 battery design has evolved rapidly since KERS first appeared. The original regulations, drawn up for the 2009 season, outlined a modest system that was an optional addition to the 2.4-litre naturally aspirated V8 engines used at the time. The power output was capped at 60 kW (80 bhp) and the energy storage system – a battery in most cases – was not allowed to release more than 400 kJ of energy per lap (equating to 6.67 seconds of use at full power). Saft’s customer was one of four constructors to run a KERS system during the 2009 season.
Although technically still legal in 2010, the Formula One Teams Association agreed not to use KERS. But the concept returned for 2011, and so did Saft. Although the energy allowance remained the same, the new regulations increased the minimum weight limit by 20 kg (to 640 kg), tipping the balance firmly in the favour of the KERS-equipped cars. The rules remained the same for the next three seasons, during which time KERS established itself as an accepted part of F1. Elsewhere, the frontrunners in LMP1 sportscar racing had switched to hybrid power from 2012, strengthening the technology’s grip on international motorsport.
The big change in F1 came in 2014 with the introduction of the current 1.6-litre V6 regulations. These saw a complete rethink on the powertrain philosophy, with a far more complicated energy recovery system (ERS), including multiple motor-generator units that would be a core part of the design.
The power of the MGU-K – analogous to the old KERS system – alone doubled to 120 kW (161 bhp). Furthermore, it was now joined by a second heat energy recovery system (MGU-H) that was theoretically unlimited in terms of power. This on its own would place tougher demands on the battery, but the capacity also went up by a factor of 10 – the cars being allowed to deploy up to 4 MJ per lap and harvest as much as 2 MJ.
“Once KERS became ERS it placed much bigger demands on the battery system,” comments Sennet. “We managed to push the power capability further than we initially thought would be possible, but we’ve also been able to provide more energy. Power and energy don’t necessarily go hand in hand: they typically work at odds in terms of electrode designs and material choices. So to push both of those, while reducing weight, and to develop that in a compressed timescale, is very challenging.”
Another milestone came in 2018 when a revised set of regulations limited the teams to two batteries per driver per season. This put an even greater emphasis on battery life. “It was a cakewalk in comparison when you could change the battery six or seven times a season,” jokes Sennet.
The durability challenge relates not just to the chemical and structural design of the cells, but also the hardware and software used in the battery management system (BMS). Once a relatively simple device to monitor the state of the battery and provide basic safety features, this is now a hugely sophisticated piece of engineering in its own right, collecting vast quantities of data and applying complex algorithms to manage the cell as effectively as possible.
“The better you can get at predicting what your battery has experienced, the better you can optimise it for the future,” comments Sennet. “A battery is like a living object – it remembers what you’ve done to it. No two races are the same, so you need to know what it’s been through.
“For instance, if you have a cold race or a hot race; a tight and twisty circuit versus one with lots of long straights; it all wears on the battery differently. But as long as you can track that and characterise it you know how much the battery has got left to give.”
While battery chemistry might be new to F1 teams, datalogging is very much familiar ground. “I’m constantly amazed by our motorsport customers when they show us the data from the battery,” notes Sennet. “They’ll say, ‘this was a rainy race in Canada’ or something like that and there is an appreciable difference in the data. That’s a reflection of the mentality in motorsport – if it’s over-designed by even a few percentage points, they want to know what they can get out of that.”
This competitive spirit has driven a constant process of evolution. Saft began with a development of one of its existing cell designs – an evolution of which continues to be used in some motorsport applications today. Since then, the company has also developed a prismatic pouch cell using the same basic chemistry, which is said to offer improved weight and space-efficiency, cost benefits and safety advantages.
Looking to the future
Saft is still heavily involved in F1 ERS systems, but it has also begun branching out into additional racing series, expressing interest in all-electric and hybrid racing series as the opportunities arise.
The company’s background in F1 has provided it with an ideal starting point for these new challenges. “At the end of the day, it all comes down to the customer’s requirements. Everyone has targets for power, energy, how many charge and discharge cycles it needs to last for, what packaging volume it needs to fit into, and what temperature it needs to run at,” comments Sennet. “At the beginning of our work in Formula 1, the very high temperature, high power requirements were something we hadn’t really seen before, but between aerospace, defence and racing I think we’ve covered pretty much all the possible combinations now.”
Synergies between these various sectors still exist, she says: “It’s remarkable where some of these similarities occur. There are parallels even between the F1 systems and the extreme environmental conditions encountered in deep sea drilling. And it’s not just in the applications but in the customers. We work with NASA and we work with racing customers, and we see the same type of people and the same approach to innovation at both.”
When it comes to road cars, the hottest topic in battery development at the moment is solid state cells. These still use the same principle as other forms of lithium ion, but – as the name implies – they use a solid electrolyte as opposed to the traditional liquid or polymer materials.
“Solid state is definitely going to help with high energy demands, and there are benefits in terms of safety and cost, so I can see a lot of interest from road car manufacturers,” comments Sennet. “It’s not necessarily so much about high power, though, so it’s hard to say if it’ll have as much impact in racing. We still have plenty of way to go with other forms of lithium ion – the term covers a broad range of chemistries, it’s not like NiCad or nickel-metal hydride where they were essentially one technology.”
Which option is used in each motorsport application will depend on the regulations and the duty cycle that’s involved. The batteries used in a fuel cell vehicle, a hybrid and a fully electric racer will vary considerably, on top of which you have different requirements for race duration, price and long-term durability. It certainly won’t be a one-size-fits-all solution.
Even at the top end, though, Sennet believes that the lessons learned from racing will be able to be fed back directly into mainstream applications: “Some of the special tailoring that we do for motorsport might not be transferable to high volume applications, but the basics absolutely can be transferred. The electrode design, the chemical composition, the manufacturing processes are directly applicable.”
In fact, low volume projects in motorsport and defence can be a great enabler for these technologies, she points out: “Road cars face so many more challenges in terms of the production volumes and the labyrinthine safety regulations, so it provides a great platform to develop new ideas before they have to face those challenges. There are a lot of programmes out there to turn defence products into commercial products. In many instances, the commercial market wouldn’t have been able to overcome the high entry costs, but you can test something out in much smaller volumes in motorsport or defence and then apply that to mainstream applications. We refer to it as the race to be second.”
Who knows, maybe by 2030 Lewis Hamilton will be on his 18th World Championship and a 51-year old Kimi Räikkönen will be looking forward to his 28th season in Formula 1? Whatever happens, you can bet that battery technology will play a far greater role in the sport than it does today.