EV dreamers can’t seem to resist Lotus: The British carmaker’s featherweight Elise convertible inspired the Tesla Roadster in 2008. Sixteen years later, Nyobolt has harnessed a redesigned Lotus Exige, the Elise’s hardtop cousin, to claim breakthrough DC charging times of 5 minutes or less.
The U.K. battery company has partnered with Julian Thomson, the Elise’s original designer, who’s now design director for General Motors Advanced Design Europe. The project team includes the Callum firm, whose renowned namesake is Ian Callum, the former Jaguar Land Rover design chief.
The company’s Nyobolt prototype recently demonstrated its time-saving tech, stuffing its compact battery pack from 10-to-80 percent full in 4 minutes, 37 seconds. That’s music to the ears of anyone who has spent opera-length times waiting for EVs to charge.
Nyobolt’s Reengineered Lotus Claims Five-Minute EV Chargeyoutu.be
The Cambridge-based company managed that snappy charge at Millbrook Proving Ground in Bedfordshire, hooking the two-seat coupe to a mighty 400-kilowatt fast charger after draining the battery dry on track. Nyobolt claims its “Ultra” pouch-style battery will charge at roughly twice the speed of those of today’s fastest-filling production cars. The company further says an unnamed global automaker tested and confirmed the batteries can achieve more than 4,000 fast-charge cycles, the equivalent of 600,000 miles of driving, with a mere 20 percent degradation in energy retention. Shane Davies, Nyobolt’s director of vehicle battery systems, said that longevity includes test cycling the battery from full to empty and back again, beyond the more-cautious parameters of many automakers and battery suppliers.
“We’re making a big play on charging speed,” Davies said. “But literally 0-to-100-percent cycling is what we also want to demonstrate.
“Most OEMs don’t want to stray beyond 80 or 90 percent, but we’re not seeing problems at the cell level.”
At the racetrack, that performance envelope helped this sports car charge at a blistering, consistent 350-KW rate and a peak of about 380 KW; despite both car and charger being held to a constant 500-amp current over most of the charging curve, the lower end of potential voltage.
“We think we could have gone faster,” Davies said, citing 4 minutes as a charging target.
The company isn’t saying much about its chemistry but says it has developed two forms of battery: The Ultra uses patented carbon and metal oxide anode materials, with a low-impedance cell design. An Xtreme version uses a graphite anode to deliver roughly 5-minute charges for material-handling robots, mining, and other industrial applications, with lower nominal voltages and a claimed lifespan of about 25,000 cycles.
Proprietary battery management and oversight is a critical part of the company’s tech, Davies said, including control algorithms to “ensure we have enough processing to monitor the system at the cell level, not just pack level.”
There’s one caveat to that bathroom-break charging time: The Nyobolt carries a relatively tiny, 35 kilowatt-hour pack. That compares with, say, the 84-kWh pack in a Kia EV6 crossover SUV. Even a subcompact Nissan Leaf Plus carries a 60-kWh pack, among the smallest batteries in any U.S.-market EV. With that miniature battery, the company estimates the sports car could deliver a scrawny 250-kilometer range on Europe’s WLPT cycle, which equates to roughly 200 km (125 miles) by U.S. measures. So even if the Nyobolt could add 200 km of range in 5 minutes, in this current application it could manage only about 90 minutes on the highway (at an average speed of 120 km/h) before needing to exit for a refill. The Nyobolt, Davies emphasizes, is more about generating juice quickly for racetrack runs than for demonstrating road-trip capability.
Yet that trade-off highlights a philosophy that’s gaining ground in many EV circles: If cars can charge nearly as quickly as it takes to pump a tankful of unleaded, then battery size and maximum driving range become less of an issue. Integrating a smaller battery sets off a chain of efficiency gains, including weight, price, performance and energy consumption. Even components such as brakes and crash structures can be slimmed down, because they don’t have to deal with as much mass. Each reduction brings a gain in per-kilometer energy efficiency, which counterintuitively extends ultimate range, clawing back some range losses due to the smaller battery.
“If you downsize the pack, you also reduce the cost of the pack and the cost of the vehicle, and the resources that go into a battery,” Davies said.
The happy side benefit is that “you get a much-more agile vehicle as well,” Davies said. He should know: Davies led the power-train software team for the Mercedes-AMG ONE, the roughly US $2.7 million hypercar—limited to 275 copies, all presold—developed by Mercedes-AMG and the Petronas F1 team.
The petite pack helps hold the Nyobolt’s curb weight to 1,250 kilos. That’s significantly higher than the 950 kilos of an Exige S, but still a bantamweight by the standards of modern sports cars.
Davies pointed to the Porsche Taycan, which found many buyers opting for the lighter and more-affordable of two available packs.
“Drivers were going for the smaller battery because the car handled so much better, and they weren’t lugging this huge battery around with it.”
Davies suggested many automakers might find a roughly 55-kWh battery a sweet spot between price, weight, range, and performance. Even on a modest 150-KW charger, roughly the median rate for new public DC plugs in the United States, a car with a 55-kWh Nyobolt pack could fully recharge in roughly 20 minutes. A 350-kilowatt charger, such as Electrify America’s most-powerful units, would cut that charge to about 10 minutes.
Nyobolt say it is engaged in talks with eight global automakers to potentially use its batteries in high-performance EVs. Putting the Callum-engineered Nyobolt on the street is another possibility, for a car that would easily outpace the original Tesla roadster—and definitely when it’s standing still at a charger.
“If we get the right expressions of interest, we might think about a limited run of vehicles,” Davies said.
