Going deeper into the efficiency of the Renault Z.E.15

In electric racing efficiency is key, right?

“Yes, absolutely! Essentially Formula E is an efficiency competition between electrical powertrains. It’s really important to have an efficient car given that the FIA regulations limit the amount of electrical energy available to us. This is limited to 28 kilowatt hours from the Williams battery we use.”

So 28kWh – what is that in layman’s terms?

“If we assume that the average kettle takes about two minutes to boil, you could boil approximately 280 standard kettles from that amount of energy. Then our job is to convert that electrical energy into mechanical efficiency.”

Great! So how do we do that?

“Well, the idea is to maximise that 28kWh available as it is transferred through the powertrain and to the track. This year’s regulations have allowed us to design and develop our own powertrain, which comprises the e-motor, inverter and gearbox, as well as a system to cool it all. So during development our job here at Renault Sport was to optimise the powertrain in order to maximise that efficiency and minimise energy loss in the process. Energy can be lost in different ways, such as resistance within the powertrain, excess heat generated and even lower pressure in the tyres leading to a larger contact patch with the track. We ran various simulations in different conditions to find the best solution for the season, seeing as we cannot touch the powertrain once it has been homologated by the FIA.”

Is there anything else we can do to improve efficiency?

“As with all forms of motor racing it is also vital that we can make the car as light as possible. Regulations dictate that the minimum weight (including driver) should be 888kg, so we try and stay as close to that as possible. It may seem obvious, but being as light as possible can make a huge difference to efficiency.”

And how can we relate all of that to the cars we drive around on the roads? Is there any correlation?

“Absolutely! We spent a lot of time with the electrical and transmission technicians from Renault. With years of experience developing road-going electric vehicles, we wanted to ensure we were on top of all of the latest technology.”

Renault e.dams