Williams: Burning fuel may be key to having enough battery power to finish F1 lap

Matt Harman, Williams' technical director of engineering, explains the options available to F1 teams to ensure that they have the necessary electrical energy to complete a lap

The issue is highly topical and risks becoming a thorny subject: the electric motor in Formula 1’s new power units has almost tripled its power, rising from 120 kW last year to 350 kW, but the battery capacity is only slightly greater than the one used up to 2025.

Under these assumptions, it is clear that the available electrical energy is not sufficient to cover an entire lap, which is why active aerodynamics have been developed to reduce drag. But evidently, this may not be sufficient to conserve electrical energy, and teams are now developing novel solutions to avoid finding themselves halfway down a straight with only half the available power.

Matt Harman, Williams’ engineering technical director, spoke on the sidelines of the FW48 livery launch, confirming a preview reported by Motorsport.com: in 2026 we will hear internal combustion engines “singing” even through corners, in the hope of using fuel to recharge the battery.

“Fundamentally, energy recovery on this car is going to be a challenge,” Harman explained. “We know why we have active aerodynamics on the car and therefore we need to make sure that we can maximise that recovery.

“So, one of the things you might see is drivers pulling a lot lower gears than you've ever seen before to try and maximise that type of recovery in very key stages of the lap. As it stands right now, a driver would very rarely pull first gear. You may see that.

“Now, that gives us challenges further on in the car, because that is a stability problem. So then you're into how you control the power unit, how you control some of the stability in the rear of your car, the systems that you have in there to do that.

“There's lots of things that we have to look at and that's one very specific characteristic of this particular car – and also will require the driver to adapt their style to that, because they won't naturally want to do that, I don't think.”

Williams FW48

Photo by: Williams

As a result, Harman confirmed that the team was looking to “promote maximum energy recovery during the lap in every way" that it could, and teased some solutions that could creep into F1 races. He explained that teams “absolutely” would run the engines at maximum revs through some corners to boost electrical power.

The topic was then addressed by Angelos Tsiaparas, Willaims head of trackside engineering.

“Imagine a hybrid road car,” he explained. “Let’s say you have a car with equal thermal and electrical power on it. So, you don't have to press the brake pedal to harvest electrical energy through your electric motor.

“At any point you decide, you can turn the electric motor in negative torque or negative power, let's say, in harvesting mode and effectively burn fuel to create some electricity. This is happening even in the current regulations. It's not something really new.

“It's just that because the electrical element in ‘26 is so much bigger, almost three times more powerful than the previous era of power units, such strategies will become way more potent.”

When asked about how the power units will influence the pecking order in 2026, Harman explained that integration between Formula 1’s new engines and the updated chassis will be key to success this year.

“I think your key performance driver will depend on where the subsystems performance are in their own right. I mean, you know, if you've got a very advanced power unit and chassis integration, you could be at one end of that optimisation. If you've got one that's struggling in some areas, then you may have to change very much the way you run your car.

“It'll be very specific. And, you know, we're finding these things out on a daily basis, which is interesting. It's actually quite exciting.”