‘Electric Refueling’ Claims Minutes to Charge Le Mans Car

Philip Oakley 2nd July 2019

The Le Mans BEV race team claiming superfast charging says it will use the concept of ‘electric refueling’ in the iconic endurance event by 2023.

InMotion claims it will be able to charge a vehicle in two minutes using a rate of two 600kW chargers – that’s more than 14 times the speed of a standard rapid charger and almost six times the speed of a 120kW Tesla Supercharger.

However, before that much development needs to take place, with the team using a Ginetta race car chassis, stuffed full of battery modules and motors, to charge in seven and a half minutes using one 350kW charger.

Yet, behind this refueling concept lies a team of students at the Eindhoven University of Technology in the Netherlands. It claims to have stolen a march over commercial rivals thanks to an academic focus. As team manager Noud Schoenmakers told TU-Automotive: “Because it’s a university research project, rather than purely commercial, the time constraints are less and more budget can be put into R&D.”

Electric refueling requires very high charging voltage and is achieved by keeping the batteries cool at a temperature between 44°C and 50°C. This means the batteries are charging at their optimum temperatures, similar to how the Volkswagen ID.R’s batteries are charged when it has completed a one lap run at the Nordschleife. Schoenmakers said that under-cooled or over-cooled batteries result in battery degradation, meaning the batteries do not charge as quickly and their lifespan when charged is reduced.

Currently, the team is developing its technology in a Ginetta race car chassis, which will not be the car that races at Le Mans in four years time. The battery in the Ginetta has voltage of 657-volts and a maximum capacity of 52kWh. It can recharge from 20% to 80% in seven and a half minutes, using one 350kW charger. The powertrain, meanwhile, has maximum output of 400kW. With the car weighing 3,196.7 pounds, it can reach 62mph in 3.5 seconds. However, with all that voltage, charging a car with InMotion’s technology is a lot more hazardous than current systems.

The Vision, meanwhile, will have two 600kW chargers, produced by Dutch EV charging specialists Heliox, with the batteries operating in the same temperature range as on the Ginetta. Schoenmakers said that the team is “aiming to be faster than the GTE-Pro class”, which sets lap times around the 3:50 mark. With a charging time of 2 minutes from the powerful 600kW dual chargers, a pitstop should be roughly the same time as a car which is refueling.

The power will be supplied from a “large battery buffer inside the pitlane”, Schoenmakers told us. “This buffer is large enough to supply the required power to charge the batteries; also, the buffer can be charged during the race.”

Pitstops will be largely similar to any other Le Mans entrant, Schoenmakers said. Every 10 laps, which equals out to a 45 minute stint at Le Mans, the car will pull up into the box outside the team’s garage and the two 600kW chargers – or the single 350kW charger in the case of the Ginetta – will be plugged in. The team will then be able to change the tyres, fix any minor problems with the car, or change the driver. Starting next year at Le Mans, cars will have to refuel first and then change tyres or fix issues, but it’s not clear if this will be the same for InMotion.

350kW charging is not unheard of in the automotive world. The CharIN initiative, with automakers such as Volkswagen, BMW, Ford and Hyundai involved, is pioneering a 350kW charging system for road cars. Dr Richard Collins, senior technology analyst at IDTechEX, told TU-Automotive that charging a 52kWh battery in seven and a half minutes with this amount of power was “feasible, although the constant quick charging will degrade the battery at a higher rate”.

Because it’s a 24-hour race, battery degradation shouldn’t matter too much. However, it will be a lot more relevant to road cars, since batteries are expensive and not easily replaceable in current BEVs. One thing which can dramatically change the performance and charging of a battery is temperature, with Collins quick to stress that the temperatures InMotion is planning to use – 44°C to 50°C – are typically “on the high side for battery temperatures”. However, he also said that batteries can be “prepped for optimised charging and performance” at certain temperatures, much like with Volkswagen ID.R electric record setter using charging temperatures to get the most performance out of the battery, and how Tesla prepares its cars for charging as to charge quickly and for optimal performance. It’s very possible InMotion is doing something similar.

InMotion will be in the experimental ‘Garage 56’ class, meaning it’s not racing any of the other 60-odd competitors – it’s racing the race itself, in an attempt to get to the end. If it can finish an undoubtedly gruelling 24 hour race, the team will have achieved its aim. The next step, maybe the hardest, will be the ultimate challenge: to develop the electric refueling technology for use on the road.