Abstract
Electric- and hybrid-electric bus deployments have sometimes failed because the operating agencies did not have a clear understanding of how the performance capabilities of any particular bus match up with the requirements of the operational duty cycle. Batteries are frequently subjected to over-discharge and overor under-charge and other operational conditions that progressively degrade the performance and durability of the battery. The Data Acquisition System (DAS) developed by the Center for Energy, Transportation and the Environment (CETE) at the University of Tennessee at Chattanooga (UTC) permits operating agencies to understand, in real time, the impact that an operator and/or service requirement has on the entire electric- or hybrid-electric propulsion system and, more specifically, the batteries. It can be used to increase the utility and successful implementation of a electric- or hybrid-electric bus fleet by providing data on driving techniques, energy consumption versus road/load conditions and the energy requirements of existing and potential routes. In essence, this operational mode of the DAS system performs the functions of a digital storage oscilloscope, thereby enabling sophisticated evaluation and diagnosis. Three prototype DAS units were developed, fabricated, and installed on battery-electric buses operating in Santa Barbara, California, and Emory University in Atlanta, Georgia, and on a hybrid-electric bus operating in Sevierville, Tennessee. The results of these installations will be presented.