Energy management is key to the ABB FIA Formula E Championship and one of its unique identifying features. It can be the difference between winning, finishing on the podium or running out of juice, and adds another level of drama to the closely fought racing.
"Energy management is everything in Formula E," Maximilian Guenther (BMW i Andretti Motorsport) summed up after his podium finish last time out in the 2020 Marrakesh E-Prix.
To emphasise the point, if you were to drive a Formula E car flat out for the full duration of the race, the battery would be long dead and you would be nowhere near the finish line.
During the race, the drivers have a limited battery capacity at their disposal, so good energy management is vital. This means that their driving style and tactics must be adapted to these special conditions to ensure they have enough energy remaining to finish the race.
Here are some of the key areas that the drivers must focus on to manage their energy:
1. Knowing when to take it slow: In conventional motorsport, drivers are hard on the accelerator down the straight before braking as late as possible for the corners. Formula E drivers have a very different approach, they will reduce their speed into the corners several metres in advance to save energy - so any overtaking moves need to be made with this in mind.
2. Tactics: Some drivers attempt to complete the first half of the race at a constant speed, which gives them leeway in the final phase to go on the offensive. Guenther has favoured this method in both in his victory in Mexico City and his second place in Marrakesh, this effective race planning meant he had plenty of energy leftover and was able to make the decisive passes during in the closing stages.
An alternative strategy is to attack at the beginning of the race and then secure your position with more economical and defensive driving. Reigning Formula E Champion, Jean-Eric Vergne (DS Techeetah) demonstrated this masterfully in Marrakesh, progressing through the field from 11th on the grid to be battle for the podium. The Frenchman ended the race in third but would have been higher if not for an incredible dummy pass by Guenther.
3. Braking: Vergne also made use of another key feature to conserve energy in Marrakesh. In Formula E, lost braking energy can be recovered by regen. By pulling a paddle on the steering wheel, up to 75% of the energy consumed during lift and coast can be recovered. Vergne was particularly successful in Marrakesh in partially making up for the energy consumed during his overtaking. After the race, Guenther said of his rival: "His recuperation during the race was impressive."
When it goes wrong: But teams and drivers are not always able to manage energy as well as Guenther and Vergne. At the 2019 Mexico City E-Prix, an extended safety car phase compromised calculations made before the race.
The result, Pascal Wehrlein (Mahindra Racing) ran out of energy on the home straight with victory all but assured and in the same race, the Nissan e.dams pair of Oliver Rowland and Sebastien Buemi were also caught out after they also over-consumed the useable energy in their batteries.