How do the flywheels work?

When the Kinetic Power Booster is at “full charge”, the flywheels spin at 18,000 revolutions per minute. When a car is being charged, the speed gradually falls to 7,000 rpm - at that point the charging is halted because the storage facility is fully discharged. The time it takes to recharge – i.e. get the flywheels back up to maximum speed – depends on the capacity of the grid the facility is hooked up to. With a 50 kW grid it takes around 45 minutes.