KERS stands for Kinetic Energy Recovery System, which is an automotive system used to recover a moving vehicles kinetic energy under braking. The recovered energy is stored in a reservoir for later use under acceleration. KERS is used in Formula 1 vehicles to recover kinetic energy for future use. The system works by converting the energy of motion when the car decelerates into electrical energy, which is stored in a battery, supercapacitor, or as mechanical energy in a flywheel. The driver can then press a button on their steering wheel, discharging the battery to motion of the drive shaft and giving their vehicle a boost of power. KERS uses three main components to do its job: a Motor/Generator Unit (MGU), a Power Control Unit (PCU), and a storage device. The more efficient the KERS system is, the lower the heat losses, with some systems achieving over 70% round-trip efficiency from capturing energy at the rear axle, converting it to electricity, storing it in the battery, pulling it out of the battery, and then finally converting it to energy at the rear axle again.