24 “This is about building cars for the future and we want to put in the very best technology we can,” says Pearson. “Moving from 400 V to 800 V gives you all those cumulative marginal gains that ultimately end up creating a better system. “We want to be part of developing and demonstrating the technologies that people want to be using in the next 10 years, rather than what has been used for the last 10. But, if, from a third party perspective, a company wanted a 400 V system, it’s very adaptable to scale our battery packs, and change the systems and components to work at different voltage levels.” He says the company would not have been able to develop to the 800 V architecture if it had started even one year earlier, as the supply chain for this niche classic-car application did not exist. As a result, the company is pioneering the way in this space. “We are really the first to do it properly and it’s a very exciting place to be,” he adds. The powertrain layout was one of the first considerations, with the aim of retaining the rear-wheel drive of the original car, as that best suits the suspension and driving characteristics. The team carried out feasibility studies on two potential layouts, eventually choosing a rear-axle, direct-drive solution over a front-mounted, propshaft-coupled unit. Pearson explains: “We chose the direct drive due to the reduction in overall powertrain mass and reduced overall packing volume, which meant we could use the gearbox tunnel and propshaft position for other systems. Fewer rotating parts also meant there was reduced noise, vibration and harshness, and improved powertrain efficiency.” The team consulted a variety of motor and gearbox suppliers, and ultimately selected a combined drive unit that includes a park lock. The unit used on the first two prototype vehicles contains an open differential, but the production cars will feature a locking differential and a higher torque output, giving broader access to the available 400 bhp (and above). Helical cut gears will also be used for the single-speed transmission, which promises superior noise, vibration and harshness performance with a zeroperceivable backlash when changing direction. Temperature is managed by a water ethylene-glycol coolant system, with an oil cooler on standby if hightemperature testing shows it is needed for reliability. Bespoke driveshafts connect directly to the rear wheels, with the motor installed via a bespoke anti-vibration mounting system. The in-house developed Motor Control Unit controls regenerative braking, hill hold and cruise control via the inverter through the bespoke software. “Across the board, almost all of the software is ours,” Pearson explains. “We’ve had a fantastic software engineer working with us from day one, and we have a second starting in December, who is going to come and help take it from initial driving software to full-function software, through all our safety tests.” “Everything is designed to the spirit of ISO 26262 road vehicles – functional safety standards – which is a real rarity in this industry as it is relatively underregulated. We own all that software, and it’s vital for us to be able to control it, be confident in its safety and, potentially, to be able to apply it as a software product to other clients as well.” Outside of the standard park, reverse and neutral drive modes, which mimic what was available on the original vehicle, the company has added its own specific engine-mapping modes. However, where Tesla has its ‘Ludicrous Mode’ for extreme power-dumping performance, the Evice options are, well, a little more refined. January/February 2025 | E-Mobility Engineering The vehicle employs a direct-drive rear-wheeldrive system, minimising rotating parts, and reducing noise, vibration and harshness Everything is designed to the spirit of ISO 26262 road vehicles – a real rarity in this industry as it is relatively underregulated
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