Last week I spent a couple days with ePower Engine Systems working my way through a variety of business and technical due diligence issues. As always happens with new clients, it was a full immersion course in how ePower's technology works, what the documented performance of the current tractor is, and how that performance is expected to change as ePower:
- transitions from a four cylinder engine designed for stationary use to an EPA compliant six cylinder engine designed for the trucking industry;
- automates a new charge control system that will opportunistically charge the batteries in a more fuel efficient manner;
- evaluates the potential economic and performance advantages of using a rare earth permanent magnet generator instead of a conventional AC generator; and
- evaluates the potential economic and performance advantages of using a rare earth permanent magnet drive motor instead of a conventional AC induction motor.
ePower's original development work was done using a 197 hp John Deere diesel engine and a Marathon generator with a rated capacity of 115 kW that can be over-rated to 128 kW for brief intervals. In all but the most extreme conditions, the ePower tractor is designed to minimize generator over-rating by using an array of 56 PbC batteries from Axion Power International (NASDAQ:AXPW) for acceleration and hill climbing boost.
Since the current John Deere engine was designed for stationary use with a generator, it is not EPA compliant and its horsepower rating does not account for parasitic engine loads like power steering, air conditioning, airbrake compressor and other accessory and hotel loads. As a result, the maximum sustained generator output of the current tractor is about 93 kW.
ePower recently bought an EPA compliant 240 hp on-road Cummins diesel engine that was salvaged from a wrecked truck. Unlike the John Deere engine, the Cummins engine is rated on net useful horsepower at the flywheel after parasitic loads. It's 32 pounds lighter than the John Deere engine and has an advertised fuel consumption of 6.8 gallons per hour at 1,800 RPM. With the Cummins engine, ePower believes they'll be able to run their existing generator at full capacity without difficulty.
Over the last several months ePower has been conducting fuel economy testing of their current tractor in the Cincinnati region. The topography is best characterized as gently rolling hills with grades of 1% to 3% and typical altitude changes of up to 300 feet. The fuel economy tests were conducted according to SAE J1321 protocols using multiple trips over several 40 to 46.5 mile routes with city, suburban and highway profiles. Data was recorded at average speeds of 55 and 59 mph and any results that deviated from the average by more than 5% were excluded.
The blue bars in following graph show the documented fuel economy of the ePower tractor with a variety of loads ranging from empty to fully loaded. The red blocks at the end of the current fuel economy bars represent ePower's estimates of the incremental fuel savings that should be realizable with (1) the six cylinder Cummins engine upgrade, (2) automation of the charge control circuitry, and (3) integration of a rare earth permanent magnet generator.
For purposes of comparison, the graph also includes a single line for the national industry average across all weight classes and the goals of the DOE's Supertruck program.
Since ePower's ongoing work is by nature a research and development project, there can be no assurances that the planned tractor upgrades can be completed over the next several months or that the third generation tractor will meet current performance expectations.
Disclosure: I am long AXPW.