This International Standard applies to onboard lithium-ion traction batteries for railway applications. This standard specifies the design, operation parameters, safety recommendations, data exchange, routine and type tests, as well as marking and designation. Battery systems described in this standard are used for the energy storage system (ESS) for the traction power of railway vehicles such as hybrid vehicles as defined in IEC 62864-1. Auxiliary batteries to supply power only to the auxiliary equipment are excluded. Subcomponents within the battery systems, e.g. battery management system (BMS) and battery thermal management system (BTMS), are also covered in this standard. Power conversion equipment (e.g. chopper, converter, etc.), inductors, capacitors and switchgear are excluded from the scope of this standard. General requirements for onboard ESS are described in IEC 62864-1:2016. This standard specifies the lithium-ion battery technology but does not prevent the use of battery technologies other than lithium-ion technology for application as traction batteries. A hybrid energy storage system, which uses two or more energy storage technologies combined, e.g. a traction battery and double layer capacitors, is not covered in this standard. However, if different technologies of energy storage systems are used on the same railway vehicle and managed independently, each independent energy storage system is covered by its own standard.