The marriage between the ERS and the engine is one of the key parts to making a Power Unit work to the best of its abilities, and it’s something that teams focus on every race weekend. It’s all about working out how to deliver and recover the energy in an optimum way. Before a race weekend, simulations are run with the computer working out the ideal set-ups and scenarios. These are then tested out for the first time in the Driver in Loop (DiL) simulator, to create a profile for that specific track. Each circuit will require the ERS system to recover and deploy energy in different ways, so the DiL is a good first step in understanding how the computer results are working. The profile created on the DiL is then moved onto the dyno, where the hardware is really put through its paces. This step is all about seeing what the hardware can deliver. Once work is complete on the dyno, it’s onwards to the race track, to see and understand the reality. Preparing the ERS for each track all depends on the amount of braking performance and cornering performance of the car, to work out how much full throttle time a lap will take – because this will determine how long the MGU-K needs to run, how much energy needs to be taken from the battery, and also how long the MGU-H will be absorbing energy and how much energy it can put into the battery.The learnings are taken from Friday’s practice running and worked on overnight, before then being deployed on Saturday in Qualifying, where the battery can be depleted fully. During the race, the battery will stay at the same state of charge. This is because, unlike in an electric car where you fill the battery and drain it, the ERS recovers what it can, stores it briefly in the lap and deploys it at the best time.