The Hymotion PHEV module requires minimal modification to the stock vehicle. All necessary components and safety features are integrated and contained within the module, including: batteries, power electronics, crash sensors, power electronics, charger, battery management system, safety sensors and manual-electric interlock. The system does not require removal of the OEM battery pack and can be installed in less than 2 hours, according to the companies.

After focusing on fleet testing this year, A123systems intends to market the PHEV conversion modules starting in 2008.

It will be certified to meet all applicable new car test standards and will be installed by trained mechanics in less than 2 hours, without any changes to the underlying electronics, mechanics or materially useable space of the production hybrid other than the installation of the plug in the rear bumper.

The applicable market in the US for standard production hybrids will be approaching 1 million through the course of this year. With almost two dozen hybrid models expected by the end of 2008, there will be 5 million standard hybrids on the road by 2010. At an initial 40 mile module installed price of $10,000 supported with a $3,500 tax credit, the payback period for a fleet owner with $3.00/gallon gas is 2.5 years, against an expected life of 10 or more years. The payback period for the average commuter driving 11,000 miles per year would be 5.5 years. These calculations place no value on the net reduction of approximately 100 tons of carbon dioxide and other emissions over the life of the vehicle and take no account of the cost reductions which could accrue from additional materials research and increasing production volumes.

—David Vieau

Vieau urged the senators to apply any tax incentive applicable to customers of factory original plug-in hybrids some years out to tested, standardized plug-in modules offered earlier by qualified companies.

We estimate a fivefold increase in demand for these modules from an increasingly responsive American public as a result of providing for this early responder tax credit.

—David Vieau

The current Hymotion/A123Systems PHEV module is a 5 kWh pack that operates only in the all-electric mode of the conventional Prius—i.e., maximum charge-depletion mode. (As a contrast, the Energy CS Prius—which replaces the OEM pack—has two modes of operation: EV mode and a blended mode designed to deliver better emissions performance.)

A Hymotion PHEV was one of several plug-ins already tested by Argonne National Laboratory to assess fuel economy, energy consumption and emissions. Among their conclusions, the researchers found that NOx and THC emissions from both the Hymotion and Energy CS packs exceeded those of the production Prius in city cycle testing. (Earlier post.)

The issue is currently faced by all the PHEV conversions. The production Prius loads the engine and warms the catalyst during cold-start operations to meet SULEV emissions standards.

With the maximum charge-depletion operation of the Hymotion Prius, the engine is used when a speed or power threshold is reached. If the power required form the engine is large before the catalyst is warmed up, the emissions may be impacted significantly.

—“Testing and Analysis of Three Plug-in Hybrid Electric Vehicles”

Argonne test results found that while NO_x and THC emissions for the production Prius and the PHEV Prius were similar on the first test cycle, subsequent cycles had higher emissions levels for the PHEV since the engine temperature and catalyst temperature were not at the proper operating level.

In consecutive city cycle testing, Argonne found that fuel economy for the PHEV ranged from 148 mpg, up to 200 mpg, and down to 66.4 mpg as the battery depleted. Highway cycle results yielded fuel economy ranging from 112 mpg down to 62.4 mpg.

The Argonne researchers also use a Utility Factor weighted analysis to calculate composite fuel economy and energy usage. A petroleum displacement factor (PDF) characterizes how aggressively electrical energy used in charge-depletion mode displaces petroleum as compared to the charge-sustaining operation of the vehicle. The PHEV-equivalent mileage is the calculated range of the vehicle if it were to operate purely as a full electric vehicle. (See table at right.)

Based on this initial testing project, the Argonne team concluded that there are three primary areas of research required “to create a successful PHEV”:

• The trade-off of battery cost to petroleum displacement.

• Emissions control strategies in charge-depletion operation to maximize petroleum displacement while emissions during cold starts and the many engine restart conditions.

• The impact of reduced engine efficiency due to operation under reduced load during charge-depletion mode.

Resources:

• David Vieau Testimony

• Testing and Analysis of Three Plug-in Hybrid Electric Vehicles (SAE 2007-01-0283)