Abstract: With the increase in the number of electric vehicles, fire accidents caused by thermal runaway of power batteries have occurred from time to time. Evaluating the risk of thermal runaway is one of the important means to improve the safety performance of electric vehicles, but there is no quantitative evaluation method in the industry. In response to the above issues, an electric vehicle combustion test platform has been established, and a large number of thermal runaway induced electric vehicle fire simulation tests have been conducted. The following reference indicators and some potential indicators that can be used for evaluating the harmfulness of electric vehicle thermal runaway have been extracted: the time interval from the start of the test to the thermal runaway of the power battery can be used as an effective indicator for battery failure warning; The time interval from thermal runaway to vehicle fire and the temperature inside the vehicle can be used as safety indicators for passenger evacuation; The time when the volume fraction of smoke exceeds the standard and its relationship with the time of ignition can be used as a hazard indicator for toxic gases in the cab; The volume fraction of combustible gases inside the vehicle and the intensity of thermal radiation outside the vehicle can be used as indicators to evaluate the risk of explosion and ignition of adjacent vehicles. By proposing the above evaluation indicators, reference can be provided for the subsequent formation of quantitative evaluation methods and related standards.

Key words: electric vehicle, thermal runaway, hazard, assessment scheme