Battery Electric Transit Bus Safety and Performance Testing: A Review of Current Practices and Correlation to Battery Failure Modes

Transit agencies globally have been investing in more battery electric buses (BEB) in an effort to combat growing negative externalities stemming from the use of traditional petrochemicals fuels in combustion vehicles. These buses use new battery technologies to cut carbon pollution and promote cleaner, faster, and safer rides. As new electrification technologies continue to penetrate the bus transit market, there is a continuous need to evaluate the safety and performance of these battery systems. To meet the need of ensuring the safety and performance of battery technologies in transit buses, regulations and standards have been established and are continuously refined to prescribe best testing and industry practices. In a joint research effort between The Ohio State University and the Federal Transit Administration (FTA), this paper details the current state of battery standards and regulations and how these standards and regulations tie back to battery failure modes and effects. Given there are numerous different overlapping regulations and standards, this paper presents the generalized testing practices for safety and performance of BEBs. These practices are independent of any specific regulation or standard and represent the current state of the art in battery and BEB testing. The safety tests are referenced to the failure modes and effects that these tests are intended to cover. Furthermore, this paper also presents a summary of the current gaps that exist in BEB safety and performance testing. With this, a more comprehensive understanding of BEB safety and performance testing is established and future needs for testing are identified.