High power and high density in EV batteries - the Formula 1 approach

Paul McNamara, Technical Director of Williams Advanced Engineering tells Simon Duval Smith about the racing company’s Adaptive Multi-Chem technology and how technology transfer from Formula 1 will benefit volume production EVs in the future

Paul McNamara

Paul McNamara

Increasing the energy and power density of batteries is widely regarded as electrification’s greatest challenge. With the industry ramping up production of electric and hybrid vehicles, there is significant demand for new battery technologies. Manufacturers are usually faced with a compromise between energy and power density as they try to minimise the size and weight of battery packs for a target performance level. Williams Advanced Engineering’s Adaptive Multi-Chem technology uses a state-of-the-art, bi-directional DC/DC converter to deliver high energy and high power density in a single pack.

Use of Adaptive Multi-Chem technology enables a 37% increase in energy density for a target power density. The system is highly adaptable, with semi-independent sizing of energy and power cells through the use of scalable blocks. A compact thermal management system is able to provide sufficient cooling without unnecessary bulk, improving packaging. Paul McNamara says that Adaptive Multi-Chem will allow the use of novel, ultra-high energy and power dense cell technologies in a variety of high performance applications including motorsport, performance cars and aerospace.

The Williams Advanced Engineering stand at the CENEX show on September 4&5 features a battery module that incorporates Adaptive Multi-Chem technology, with a total stored energy of 60kWh, with a core battery mass of 345kg. Peak deployment power is 550kW (20 second pulse), and peak regeneration power is 550kW (10 second pulse).

A powerful partnership with Unipart

The Multi-Chem project is separate from the manufacturing initiative that Williams has with Unipart Manufacturing, as Paul tells me: "Yes, in that one project is a technology development programme and the other is a factory. The Hyperbat initiative is to allow us to manufacture, in relatively low volume, up to 5,000 units per year, complete battery packs. What we are offering the industry is our expertise as a tier 1 supplier of batteries, completely engineered and validated and certified." Through its partnership with Unipart, Williams has gained the advantage of Unipart's existing manufacturing facility, with its economies of scale in labour and equipment, as Paul says. "For us, as a motorsport organisation, we needed a partner to bring that industrialisation experience to the project."

Cell structure for high energy and high density

The Multi-Chem technology will be incorporated into the Hyperbat production portfolio as Paul tells me: "We will be able to make the Multi-Chem batteries at Hyperbat but what we are showing here today is a new technology; something that the industry has been talking about for some time. At present, in most cell products, one either has high power cells or high energy cells, one can't have both. Simply put, one can have high capacity, but not take out high power, or one can have very high power but you cannot store a large capacity. The industry keeps asking for both so what we are doing is combining high power cells with limited their limited energy storage capacity, with some cells that have high energy storage but with limited power capacity. These high power cells would typically be used to drive a cycle such as the need for high power in short bursts, as in a race car going around a track, with Multi-Chem, we can also provide the 'deep cycle' element."

Towards the magic bullet battery technology?

The global battery and automotive market has been waiting, since the first electric car at the turn of the 19th century, for better battery chemistry with high power density, lighter weight and technology that will give greater real-world range. Paul says that Multi-Chem is intended to take the existing chemistry and optimise it. "We are looking at existing technology and, trying to predict where it will go, and find the best possible 'pack' one can make from it. If someone does come along with a magical chemistry then we will not need to do all of this. Our judgement is that no-one is going to produce an 'industrialise-able' magic new chemistry in anything less than say, 15 years. Therefore the engineers need to say, 'This is what the industry and the chemistry can provide for us, how do I take that and make the best product?'

Electric vehicle makers and pundits often boast of the 100% efficiency of EV powertrains and this makes an interesting counterpoint to Formula 1 engineering, where the efficiency of powertrains has been lifted to more than 50% - comparing favourably with the accepted 30% efficiency of road-going vehicle powertrains. Paul says that there is a definite technology transfer from Formula 1: "There is no doubt that what Williams is bringing to the road car market has come from the Formula 1 background, whether that is in aerodynamics, lightweighting or electrification but I do think that OEMs are not highly focused on providing better, more efficient solutions. Whether that is on their electric vehicles or indeed on internal combustion-engined vehicles."

Cell and battery construction technology - a combined approach

Battery cell technology can be broadly divided between pouch and cylinder or other shape units within the battery construction; Paul says that the Multi-Chem solution is a combination of these formats. "The module that we are showing here at CENEX has cylindrical cells for the energy storage and pouch cells for the power."

Monitoring of cell condition, performance, voltage differences, gas production and safety issues have been much discussed in the seminars at CENEX and these challenges require increasingly complex sensor technology. With the combination found in the Multi-Chem battery pack, Paul says that the Williams Advanced Engineering team has had to design some very special monitoring systems. "The two types of cell have to be separated and controlled with a DC-DC converter between them because they will end up sitting at different voltages and one needs to be able to regulate the voltage for the different parts of the unit. What we have is a single board in each module that is combining the measurement, the control, and the DC-DC transfer between the cell elements. These boards are all 'talking' to a master Battery Management System ((BMS) that is regulating the behaviour of each of these modules. A large part of the innovative technology is the electronics hardware and software, that we have developed totally in-house."

This is an important innovation as if cells of varying voltage and capacity behaviour were connected in series, as in many EV battery packs, the most discharged cells would dictate charging etc rates, as Paul says, "Yes, one must manage the various cells actively, not passively."

Cost and technology transfer

Technology like this costs, but is application-essential as Paul tells me, "Yes, it is definitely more costly but you have to know what your application is. What we are showing at the CENEX show today is very much geared towards motorsport and high performance and low volume applications. This is where we see the first application of this type of technology because those applications need the very high power, and they want energy storage, in a comparatively lightweight package. The technology can then trickle down to the mainstream, through the control technologies, through the economies of scale and the learning that will come from that."

I ask Paul if the hard- and software cost is amortisable in a volume production application; he says the software is the key to building volume: "The good thing about the software is that it can build through lots of different industry applications, places that it comes from and can be used in. The philosophy that we have embraced on the hardware side is to go for a relatively low-powered DC-DC convertor in each module that we can then mass produce, rather than one bespoke unit per pack."

A very special supply chain

The UK is often mooted as an intellectual powerhouse but poor on turning great ideas and inventions into profitable production realities, Paul says that Williams' supply base is a mixture of local and global. "We do work globally but virtually all the parts, excepting the cells, come from the UK. Cells are from the Far East, and the US. If you look at the module we are showing, it has Samsung cells, the pouches are from A123."

Advanced EV tech - a great opportunity for the UK?

The UK is often mooted as an intellectual powerhouse but poor on turning great ideas and inventions into profitable production realities, Paul says that Williams' supply base is a mixture of local and global. "We do work globally but virtually all the parts, excepting the cells, come from the UK. Cells are from the Far East, and the US. If you look at the module we are showing, it has Samsung cells, the pouches are from A123."

I ask Paul if the rise of EV technology and its inevitably innovation-rich landscape could bring a lot of jobs and revenue back to the UK R&D and manufacturing base? He says that cell manufacture will stay in low-cost locations but that sophisticated control and management can be the UK's forte. "What we are saying is that the cells that you can source globally, from China for example, can be incorporated into the new generation of intelligent power sources, we then apply a lot of clever engineering on top, we can use those and add a lot of value."