ePower’s Series Hybrid Electric Drive – Unmatched Fuel Economy for Heavy Trucks
Over the last couple weeks there’s been a lot of message board chatter about ePower Engine Systems, a transportation technology company that has selected the PbC® battery from Axion Power International (AXPW) for its series hybrid electric drivetrain for over-the-road freight haulers who drive heavy Class 8 tractors. Since I introduced ePower to Axion and have tracked their progress for a couple years, I called ePower’s CEO Andy Claypole to ask his permission to share what I’ve learned about ePower’s hybrid electric drivetrain.
After a series of phone calls and e-mails, Andy graciously sent me a technical presentation on ePower's series hybrid drive and gave me permission to share the presentation with readers and discuss ePower and its technology in greater detail. Click here to download a copy of ePower's presentation.
ePower Engine Systems LLC is a closely-held advanced transportation technology developer that’s using inexpensive off-the-shelf components to bring series electric drive, the mainstay of the nation’s rail transportation system, to highway transportation. Their goal is to narrow the fuel efficiency gap between 480 ton miles per gallon for railroads and 110 ton miles per gallon for heavy trucks.
In a truck with series electric drive, there is no mechanical connection between the engine and the wheels. Instead, the engine powers a generator and electricity from the generator powers an electric drive motor. This configuration maximizes fuel efficiency by running the engine at its optimal RPM and eliminates the need for complex heavy truck transmissions while delivering the instantaneous peak torque of an electric motor.
In furtherance of their goal to maximize fuel efficiency, ePower takes series electric drive a step further by sizing the generator for steady vehicle state operations at highway speed and using an array of 52 PbC batteries to provide additional power for acceleration and hill climbing, and increased energy savings from regenerative braking. The ePower drivetrain is a true series hybrid electric drive and a first for the trucking industry. The design is suboptimal for mountainous routes with substantial elevation changes, but it’s extremely efficient in flatter terrain.
While a typical Class 8 tractor operating in the US with an 80,000 pound gross vehicle weight achieves fuel economy in the 5.2 mpg range, the same truck with an ePower system will deliver fuel economy of 10 to 14 mpg, values that crush the DOE’s 2018 SuperTruck target of 6.8 mpg for conventional heavy trucks. It works out to an annual fuel savings of roughly 11,500 gallons per vehicle.
During the startup phase, ePower has focused on the retrofit market because around 37% of the 2.7 million trucks in the US-fleet are more than five but less than twelve years old. These trucks have outlived their original drivetrain warranties and are often less efficient than newer trucks, but they have substantial remaining useful life in their chassis, bodies and other components.
The cost of converting a tractor with a conventional diesel drivetrain to a series hybrid electric drivetrain is approximately $70,000 (batteries included) and ePower believes its retrofits will pay for themselves through fuel savings alone in 18 to 24 months.
Currently, ePower is doing all required retrofit work in its own facility. Once its system is fully developed and proven, ePower intends to provide the necessary conversion components in kit form for sale to certified installers including fleet operators and other service entities. It also hopes to license its technologies and systems upstream into the OEM market.
ePower’s original design used absorbed glass mat, or AGM, batteries to provide acceleration and hill climbing boost. Unfortunately, the AGM batteries were poorly suited to long-string use and ePower was not satisfied with the frequency of battery failures. The AGM batteries also tended to degrade rapidly, which impaired acceleration and hill climbing boost while diminishing the efficiency of regenerative braking systems. ePower believes the long-string behavior and high dynamic charge acceptance of Axion’s PbC battery will overcome both of these challenges.
The PbC batteries were delivered to ePower in mid-November and installed in swappable battery boxes that will give ePower the ability to switch back and forth between the old AGM batteries and the new PbC batteries in a couple of hours. During the first week in December, ePower plans to conduct a series of benchmarking tests to compare the on-road performance of the two battery systems in the same vehicle. It will then devote the rest of December to a road show for potential customers. In early January, the first PbC powered truck will be delivered to ePower’s customer and a second AGM powered truck will be brought back into the shop for a PbC upgrade.
I believe the ePower system is intriguing for several reasons. Firstly, it’s a frontal assault on fuel costs, the biggest expense burden in the trucking industry. Secondly, ePower’s initial marketing efforts are directed at medium to large fleet operators who are more inclined to assume the risk of testing an idea in real world conditions instead of devoting years to laboratory work. Thirdly, the ePower system is an extremely efficient use of batteries. Finally, it doesn’t take much market penetration in a million-unit fleet to represent a substantial revenue base for ePower and Axion.
If results from ePower’s prototype demonstrations are favorable, there is a significant likelihood that several large freight operators will purchase multiple retrofits for similar testing programs to determine where series hybrid electric drivetrain would fit into their operations. ePower’s series hybrid electric drive system is not a silver bullet solution for all truckers and all routes, but the economics can be very compelling for firms with established routes and schedules where a series hybrid electric drivetrain can do the required work at a lower cost.
Disclosure: Author is a former director of Axion Power International (AXPW) and holds a substantial long position in its common stock.
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