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In designing vehicles with significant electric driving range, optimizing vehicle energy efficiency is a key requirement to maximize the limited energy capacity of the onboard electrochemical energy storage system. A critical factor in vehicle energy efficiency is the vehicle mass. Optimizing mass allows for the possibility of either increasing electric driving range with a constant level of electrochemical energy storage or holding the range constant while reducing the level of energy storage, thus reducing storage cost. In this paper, a methodology is outlined to study the tradeoff between the battery cost savings achieved by vehicle mass reduction for a constant electric driving range and the cost associated with lightweighting a vehicle. This methodology enables informed business decisions about the available engineering options for lightweighting early in the vehicle development process. The methodology was applied to a compact extended-range electric vehicle (EREV) concept.

Hardware-in-the-Loop (HWIL) testing is a means for validating and verifying component designs in a system context. Most current HWIL work with electrochemical systems for automotive applications has focused on the pack level, providing valuable feedback to system designers. Further benefits are realized by implementing this concept earlier in the development process; applying test vectors to an individual cell, but attenuating the stimulus and feedback to pack levels. This paper reports on a cell-level HWIL system designed to evaluate electrochemical cells and associated subsystems for advanced hybrid-electric vehicles (HEVs). The architecture of the system is described along with an example of its application applied to a commercially available supercapacitor and a state-of-charge algorithm in an HEV-based configuration.