During third-party testing, the Eaton Hybrid Power System has routinely achieved a 5-7 percent fuel savings versus comparable, non-hybrid models. It may result in a savings of one gallon of fuel per hour when idling.
At the current average diesel price of almost $2.50 per gallon, those savings equate to about $9,000 to $10,000 a truck per year in operation.
The heavy-duty hybrid electric power system features an automated manual transmission with a parallel-type “direct” hybrid system, incorporating an electric motor/generator located between the output of an automated clutch and the input to Eaton’s Fuller® UltraShift® transmission. The system captures energy generated by the diesel engine and recovers energy normally lost during braking and stores the energy in batteries. That electric torque is then sent through the motor/generator and blended with engine torque to improve vehicle performance, operate the engine in a more fuel-efficient range for a given speed and/or operate only with electric power in certain situations.
In this heavy-duty application of Eaton’s hybrid power technology, fuel efficiency and emissions reductions are best achieved both while the truck is rolling or standing still. The system’s batteries power the heating, air conditioning and vehicle electrical systems while the engine is off. When the idle reduction mode is active, engine operation is limited to battery charging, an automatically controlled process that takes approximately five minutes per hour to fully charge the system. In the proposed system design, a proprietary feature minimizes engine vibration during start-up and shutdown during the recharge periods, allowing the driver to rest without interruption.
What is clever about this system (which seems otherwise fairly similar to one being developed by Arvin Meritor) is the integration of the battery pack with the climate control systems to provide for driver comfort ("hotel" loads in industry parlance) while parked, thus limiting idling.
One thing seems strange though, according to the release this system only has enough battery capacity to manage hotel loads for an hour, whereas there the "Comfort Class"battery setup being offered by Peterbilt that only does hotel power, but does it for up to 10 hours (paired with a small diesel fired heater). So are they cheaping out on batteries to compensate for the weight and/or cost of the Eaton generator/motor? Fleets are pretty sensitive on both counts. Hopefully we will see an improvement in battery capacity that would make the system more capable.