The growing importance of electric mobility has led to an increased demand for safety technologies in the automotive sector, such as the flame retardancy of materials used for electric vehicles. The fire protection of a fully equipped rechargeable energy storage system (REESS), including battery, housing, control electronics, etc., against a fuel fire must be tested according to UNECE Regulation No. 100 Annex 8E -Fire Resistance (UNECE-R100-8E). To pass this fire retardancy requirement, the flame retardancy of the housing materials is of great importance. In this study, the flame retardancy of glass-fiber-reinforced polypropylene (PP-GF) tape laminates containing the flame retardant magnesium hydroxide and different GF amounts, as well as sandwich structures of these PP-GF tape laminates with a polypropylene bead foam (EPP) core, are investigated by a limiting oxygen index test, a UL94 test and a cone calorimeter test. Furthermore, a newly developed approach of a bench-scale fuel fire test which simulates the fire treatment of the UNECE-R100-8E on component level is used.

The fire behaviour of electric vehicles (EVs) differs from that of vehicles with combustion engines. Especially the rechargeable energy storage system (REESS) requires special fire protection measures. The fire behaviour of materials for REESS housings plays an important role in the fire resistance of such systems. Full-scale fire resistance tests like gasoline pool fire tests on complete REESS according to the UNECE-R100-8E standard are mandatory for EVs. However, these tests are not applicable for materials used for REESS housings in the material and process development state, due to the high material demand and production costs of the REESS. Standard tests like the limiting oxygen index test, UL94-V test or cone calorimeter test are insufficient to analyse the fire behaviour of thermoplastic and thermoset materials in a gasoline pool fire. This paper describes a bench-scale fuel fire test including several test criteria to evaluate materials for REESS housings on a laboratory scale. This bench-scale fire test is demonstrated on two case studies: fibre-reinforced thermoset plates and thermoplastic sandwich structures.