Pure drive

Batteries are the neglected part of the technological jigsaw that makes up electric vehicles (EVs). While most attention is focused on the development of drivetrains and the design of the vehicles themselves, the vital power pack tends to be forgotten.

Even for UK battery-development specialist Evida, energy storage is only a part of the picture - albeit, for its team, the most important one. ’We have to understand the duty cycle and the drivetrain, as well as our part of it - the energy-storage system - before we can design a battery pack for a vehicle,’ explained chief operating officer Trevor Power.

For Power and Evida’s newly appointed executive chairman, David Roberts, pure EVs are the area to focus on. ’One of the reasons I joined Evida this summer is that I can see a growing demand in the next 10 years for pure EVs, but with one important caveat: they have to be vehicles with high standards of design and manufacture, and they have to be at a good cost base for the end user,’ Roberts said.

’They’re a bit off at the moment in terms of the cost because they don’t have the volumes; that’s something of a chicken-and-egg situation. But I believe the cost will come down considerably over the next two to three years.’

Roberts has been brought into Evida after some 40 years in the automotive sector, notably with Chrysler and Aston Martin. He joined with a tranche of new senior executives, including a senior engineer and a technical sales manager; Evida’s investors are clearly setting the company on an expansion track.

However, Roberts admitted that his experience of EVs has been limited. ’I’m a petrolhead; I drive fast cars and do crazy things with them. I hadn’t been in an EV until this year, let alone driven one. But when I did, I noticed an instant change in my behaviour. It slowed me down and it made me feel better about myself and my surroundings.’

Evida’s focus on batteries for pure-electric rather than hybrid vehicles resulted from an analysis of the market, Power said. ’Hybrid vehicles have taken off quite quickly; pure electrics are somewhat behind. The use of EVs in the near future will be limited to niches: early adopters; people who are motivated to take on the vehicles and install the charging facilities so they can use them; people with a need to do relatively short journeys in metropolitan environments; people who have off-street parking so they can charge vehicles up. And that is a great thing for a small company such as us. We can latch onto the niche at the start and grow with it.’

Batteries for pure-electric cars are quite different from those for hybrids, Power added. ’They need quite different applications of battery technology. Batteries for hybrids tend to be smaller and they need to deliver a lot of power relative to their size. In a pure EV pack, the focus is very much on maximising the power you can store, because that determines your range. In a hybrid, you’re concerned more with smoothing out the peaks and the troughs in the demand of the vehicle and running the engine efficiently.’

“The use of EVs in the near future will be limited to niches and that is a great thing for small firms”

Evida’s technical centre is in the UK, with manufacturing facilities in China. However, every battery it makes is tailored for a specific vehicle. ’The technical centre [staff] talk to our customers, who tend to be OEMs, first-tier suppliers, start-ups and converters,’ Power said. ’We design bespoke packs for their vehicles to fit a specific space and provide a specific output. We don’t assemble from pre-built modules; everything is specific to the client.’

Power doesn’t believe that car batteries will ever be standardised in the way that small batteries for consumer goods are. ’There are just too many competing requirements and there have to be trade-offs,’ he said. ’Designing a battery pack is a matter of mutual adjustment between supplier and customer. A standardised battery would require too many compromises.’

Evida is focused on lithium-ion technology, which Roberts believes will be the dominant form of EV battery for many years to come. ’The technology we have now is only subject to scale,’ he said. ’My time in automotive tells me that, inevitably, the cost of a battery pack will come down, subject to one thing: volume. There will be process improvements as we go on, but as the volumes go up you’ll see economies of scale in the supply chain and that builds a momentum that brings the cost down faster. The batteries we have now are the ones that will take us into the expansion of the sector.’