Energy management and walking the tightrope between flat out raw pace and usable energy available is the cornerstone of strategy in the ABB FIA Formula E World Championship. It's all about choosing moments and knowing when to push, and getting that balance right over a 45-minute plus one lap E-Prix.
"Energy management is everything in Formula E," says Maximilian Guenther (BMW i Andretti Motorsport). And he's right. Nailing the trade-off between managing the finite amount of energy at their disposal and going flat out is the perennial battle for drivers and engineers over the course of any E-Prix.
Making the most of usable energy available and conquering energy management over a race distance of 45 minutes plus one lap is often the difference between silverware and coming home empty handed.
Here's the lowdown.
In Formula E, drivers start each race with 52kWh of usable energy out of a total battery capacity of 54kWh. They'll aim to use every last jolt of juice from that 52kWh allowance - leaving nothing on the table.
The more a driver pushes the accelerator, the greater the drain on their usable energy. If they flew flat out for the full race distance, they'd over-consume and get slapped with a penalty.
If a driver does get it wrong and goes over that limit, the remaining 2kWh buffer allows them to safely make their way back to the pits.
Knowing when to pounce and when to conserve is absolutely key for any driver looking to make the points. It's all about picking moments.
To maximise usable energy, add energy back into their cells and go faster for longer, drivers will work with their engineers to plan the best points around every Formula E circuit to lift and coast, while losing the minimum amount of ultimate lap time.
They have to calculate and decide the ideal moment to come off the power ahead of the braking zones, in a bid to reduce overall energy consumption over the course of the race.
Additionally, drivers can pull on the regenerative braking, or regen, paddle on their steering wheel to harvest kinetic energy back from the motors - pushing up to 75 per cent of energy captured during lift and coast back into the car's battery.
Slipstreaming, too, can prove key on the faster circuits on the calendar. Running in the draft of a car is more efficient, as the driver ahead is the one punching their way through the air, leaving a pocket of reduced air resistance for those following behind to take advantage of.
The racers that get all of the above just right can find themselves with up to a third more usable energy than they started the race with - key to fending off others, getting those overtaking manouevres done and pulling a gap out-front.
The other thing teams and drivers have to factor in is the energy reduction employed under Full Course Yellow (FCY) or when then MINI Electric Pacesetter Safety Car is called into action.
Here, drivers aren't running at racing speeds, so less energy is being used. To compensate, a 1kWh energy reduction is made for every lap the race is neutralised, although no energy reductions will be made if a neutralisation period extends into the final five minutes of a race.