Eaton hybrid power systems have collectively accumulated more than 300 million miles of service on more than 6,000 package and beverage delivery, refrigerated, refuse and recycling, and utility trucks, as well as city and school buses. The manufacturer of the parallel-type diesel-electric hybrid systems, however, is still hard at work enhancing the fuel economy, performance and payback for its systems.

Recently announced for its hybrid vehicle technology is a new high-capacity lithium-ion battery, which Eaton said increases fuel savings an additional 5% to 10% while also improving performance. In addition, the new battery more than doubles the engine-off capability of the system for job site operations and extends battery life, the company added.

“Drivers will notice faster acceleration with the updated hybrid propulsion system,” said Kevin Beaty, product strategy, manufacturing operations and strategic sourcing manager of hybrid power systems for Eaton. “The new battery is also designed to allow for simplified servicing of internal components.”

Eaton also is introducing a new single-phase 5-kilowatt auxiliary power generator (APG) this fall. The APG option converts high-voltage DC current from the battery to 115-volt AC current that can be used by any number of tools on the job site. The APG unit is more compact and 25 lbs. lighter than Eaton’s previous offering.

“The new APG unit offers a soft-start function that can handle high inrush loads that require an immediate boost of power,” said Gerard DeVito, engineering director for Eaton hybrid power systems. “The APG is also a fully isolated system from the high-voltage battery, which eliminates the need for a separate isolating transformer, which further reduces cost and weight.”

Both the new high capacity battery and APG will be rolled out during the fourth quarter of this year for utility fleet applications. The high capacity battery will be available for city delivery and beverage tractor applications in the third quarter of 2012.

In addition to the new battery and APG, Eaton is offering higher capacity clutches that can handle engines up to 860 ft.-lb. of torque and 300 HP. This increased capacity results in greater vehicle performance for heavier applications, the company noted, including select tandem axle configurations.

Eaton also began offering a remanufactured battery that will provide fleets with an aftermarket option. “Fleets can now extend the life of their hybrid power system for a fraction of the cost of new service units,” said Beaty.

One of the first OEMs to use hybrid systems and one of the main producers of medium-duty hybrid trucks today is Navistar. Its main offering is the International DuraStar Hybrid, a diesel hybrid electric medium-duty model available with a choice of the manufacturer’s MaxxForce engines and automatic and manual drivetrain options.

International’s hybrid vehicle is also equipped with the company’s Diamond Logic Electrical System, which integrates body equipment and the hybrid powertrain as a single piece of equipment. The programmable system features self-calibrating gauges that provide an audible alarm and visible LED indication when displaying a value out of normal operating range. On-board diagnostics monitor electrical modules and capture diagnostic faults, and trouble codes are stored and displayed on the instrument panel’s built-in LCD screen. The International DuraStar Hybrid also can be equipped with the OEM’s AWARE vehicle intelligence system to allow for real-time data collection, reporting and analysis.

Industry efforts aimed at boosting adoption of hybrid trucks continue. The Hybrid Utility Truck Working Group of HTUF (the Hybrid Truck Users Forum operated by CALSTART), which consists of more than 20 large fleets, is now actively working on Class 4 and 5 applications and is reviewing plug-in hybrid requirements. This group is credited with fostering the launch of Class 6 and 7 commercial hybrid trucks from several manufacturers.

Now in use in a growing number of fleets and applications, hybrid systems are still being refined to provide the value their manufacturers promise.