Ford Safety Performance of Rechargeable Energy Storage Systems (RESS)

2019Final ReportSuggested APA Format Citation: Masias, A. (2019, July). Ford safety performance of rechargeable energy storage systems. (Report No. DOT HS 812 756). Washington, DC: National Highway Traffic Safety Administration.PDFTech ReportDOT HS 812 756DTNH22-11-C-00214Electric vehiclesElectric batteriesFuel cellsFordrechargeable energy storage systemsRESSelectric vehiclesUnited StatesUnited States. Department of Transportation. National Highway Traffic Safety AdministrationMasias, AlvaroFord Motor Company. Research and Advanced EngineeringUnited States. Department of Transportation. National Highway Traffic Safety AdministrationNHTSA-Vehicle Safety ResearchThis study of rechargeable energy storage systems (RESS) in electrified vehicles had the objective of defining lithium ion battery performance based safety-metrics, safety performance test procedures and metrics that can be conducted at the vehicle level, informed by data at the string, module and pack level. The research involved the identification, review and assessment of existing test procedures to determine adequacy and applicability to this research. To define priority failure events in the RESS, a fault tree Analysis (FTA) was conducted that lead to the identification of crush, overcharge and short circuits as principle fault mechanisms, and provided an under-standing of the key faults within those failure modes. With the FTA and existing test procedures reviews completed, new test procedures were prepared. Test material consisting of cell strings, module and packs, made from three different cell designs and representative of current Li-ion automotive batteries, were fabricated. Testing sources with the ability to handle high energy battery abuse assessments were identified and, through the course of the research, three were used to perform the tests following the developed procedures. The testing included data acquisition for voltage, current and temperature and was supported with photographic and video files that provided the ability to relate physical events to data points of interest to the researchers. The result is a set of re-producible and repeatable test procedures that indicate the threshold levels that should not be exceeded in a vehicle fault event.80