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As part of a U.S. Department of Energy supported study, the National Renewable Energy Laboratory has benchmarked a Toyota Prius hybrid electric vehicle from three aspects: system analysis, auxiliary loads, and battery pack thermal performance. This paper focuses on the testing of the battery back out of the vehicle. More recent in-vehicle dynamometer tests have confirmed these out-of-vehicle tests. Our purpose was to understand how the batteries were packaged and performed from a thermal perspective. The Prius NiMH battery pack was tested at various temperatures (0°C, 25°C, and 40°C) and under driving cycles (HWFET, FTP, and US06). The airflow through the pack was also analyzed. Overall, we found that the U.S. Prius battery pack thermal management system incorporates interesting features and performs well under tested conditions.

The deionized water/ethylene glycol coolant used in the Ford Focus Fuel Cell Vehicle (FCV) requires very low conductivity (< 5 μS/cm) to avoid current leakage and short circuiting, presenting a unique water chemistry issue. The coolant's initially low conductivity increases as: 1) ions are released from system materials through leaching, degradation and/or corrosion, and 2) organic acids are produced by ethylene glycol degradation. Estimating the leaching potential of these ions is necessary for design and operation of fuel cell vehicles. An on-board mixed-bed, ion exchange resin filter is used to maintain low conductivity by removing leached or produced ions. Various candidate materials were evaluated for leaching potential by exposing them to coolant at the design operating temperature for several months and periodically analyzing the coolant for ions.

Mechanical shock tests for lithium metal and lithium-ion batteries often require that each cell or battery pack be subjected to multiple shocks in the positive and negative directions, of three mutually perpendicular orientations. This paper focuses on the no-disassembly requirement of those testing conditions and on the CAE methodology specifically developed to perform this assessment. Ford Motor Company developed a CAE analysis method to simulate this type of test and assess the possibility of cell dislodging. This CAE method helps identify and diagnose potential failure modes, thus guiding the Design Team in developing a strategy to meet the required performance under shock test loads. The final CAE-driven design focuses on the structural requirement and optimization, and leads to cost savings without compromising cell or pack mechanical performance.