Nissan’s recently unveiled 2017 Note, a Japan-market 5-door, is powered by what the company claims is the world’s first series-type hybrid propulsion system in a compact automobile. The Note and its so-called e-Power system show that Nissan engineers have learned to adopt elements of the battery-electric Leaf driveline (including the 80-kW/107-hp traction motor) to a hybrid configuration, albeit without plug-in capability.
The introduction of e-Power, which is slated to spread to other Nissan and possibly Renault vehicles, expands upon Nissan’s comparatively limited hybrid approach represented by the single motor, CVT-based, P2-type system as used in the 2017 Rogue Hybrid.
Nissan calls e-Power "a gateway to 100% electric cars" and provides “all the benefits of an EV without having to worry about charging the battery." Eliminating EV range anxiety and minimizing system costs appear to be the primary drivers behind the series-hybrid strategy. The company is betting on the new Note e-Power to draw customers in Japan, where more than half the passenger vehicles sold are now hybrids.
Technically a series hybrid has only an electric transmission path between the power source and the driven wheels. Diesel-electric railroad locomotives exemplify this configuration, with the diesel turning at constant speed to spin an electric generator which then powers traction motors at the locomotive’s rail wheels (trucks).
BMW’s i3 range-extender is the only true series hybrid car currently available—and it’s a B-segment compact, so it’s unclear where Nissan is staking its “world first” claim. The i3’s twin-cylinder ICE only provides power to charge the battery, where the Chevrolet Volt’s (sometimes labeled a series hybrid) Voltec electric transaxle is capable of clutching the combustion engine into the final drive via a planetary gearset to provide extra power in certain driving situations.
Series hybrids have also been built by engineering consultancies including FEV and AVL in recent years to demonstrate the type’s efficiency potential. Some have even used Wankel rotaries rather than piston engines.
Nissan’s Tokyo announcement on the Note was intentionally light on technical detail, with chief powrtrain engineer Naoki Nakada stating that minimizing the car’s battery size was a key program bogey, aimed at reducing cost (and mass).
He also noted that the Note’s lithium-ion batteries are “one-twentieth the size” of those in the Leaf, “and made to fit under the front seats without having to sacrifice interior space." If Nakada-san was speaking specifically about the battery’s total capacity that would calculate to 1.5 kWh, as the Leaf battery is rated at 30 kWh.
The ICE is Nissan’s 1.2-L gasoline triple is taken from the Micra and is calibrated for 2,500-rpm operation to charge the battery pack. To view Nissan video: https://youtu.be/TPSRE9e06wg
Recently Renault-Nissan Alliance chairman Carlos Ghosn said publicly that the new e-Power hybrid system is “definitely cost-competitive with diesel,” adding that it carries a 27% cost premium (similar to that of a comparable diesel) versus a conventional gasoline powertrain. Ghosn indicated that e-Power is capable of delivering diesel-like fuel efficiency.