Position of the battery packs and traction motor. Click to enlarge.

Weighing about 40 kg, the compact, tri-phase, high-voltage electric motor of the HY-KERS is coupled to the rear of the dual-clutch 7-speed F1 transmission. It operates through one of the transmission’s two clutches and engages one of the two gearbox primary shafts. Thus power is coupled seamlessly and instantaneously between the electric motor and the V12. The electric motor produces more than 100 hp (74.6 kW); Ferrari’s goal was to offset every kilogram increase in weight by a gain of at least one hp.

The motor cuts in during acceleration, providing instantaneous torque when moving away from a standstill and during overtaking, with torque control a function of grip, gear and accelerator pedal angle.

Depending on vehicle speed and engine load—for example in town driving—the hybrid system can also function as a full-electric drivetrain. The result is a direct reduction in consumption and emissions. The motor also features a unique cooling and lubrication system for maximum efficiency under all operating temperatures and loads. The castings of the motor are made in the Ferrari foundry, complete with Prancing Horse motif.

Motor and power electronics. Click to enlarge.

Under braking the electric drive unit acts as a generator, using the kinetic energy from the negative torque generated to recharge the batteries. This phase is controlled by a dedicated electronics module which was developed applying experience gained in F1 and, as well as managing the power supply and recharging the batteries, the module also powers the engine’s ancillaries (power steering, power-assisted brakes, air conditioning, on-board systems) via a generator mounted on the V12 engine when running 100% under electric drive. It also incorporates the hybrid system’s cooling pump.

The flat lithium-ion batteries are positioned below the floorpan of the car inside the aerodynamic underbody. The result is a center of gravity that is even lower than in the standard car. In addition, a part of the weight gained by fitting the electric motor, generator and the batteries is offset by being able to do away with the traditional starter motor and battery.

Stop & Start on the California. Hybrid technology is one of the solutions examined by Ferrari in its on-going research and development into making its production cars more efficient. Experimenting with alternative technologies represents the company’s long-term strategy after the announcement in 2007 of a five-year plan to reduce fuel consumption and emissions across the range.

A Stop & Start system is now available on the Ferrari California, reducing fuel consumption and CO₂ emissions by 6% in the ECE + EUDC combined cycle to 280 g/km—one of the most competitive of any high-performance cars, according to Ferrari. The Stop & Start cuts in after 230 milliseconds—a time so fast that the driver barely notices the engine restarting.

Another principal area of research for reducing fuel consumption has been dedicated to reducing friction within the engine. The Ferrari California’s direct-injection V8, for example, has eliminated the pumping losses created by the changes in pressure below the pistons. Inserting purge valves in the crankcase below the crank throws allows blow-by gas and oil compressed during the combustion phase to leave the crankcase without being drawn back in during the compression phase. This ensures a direct increase in engine efficiency.

In addition DLC (Diamond Like Carbon) coatings on the valve followers and superfinishing of the cam lobes reduces friction in the valve train and contributes to the overall improvement in engine friction.