IEC 62973-1:2018 applies to various rechargeable battery technologies for auxiliary power supply systems used on rolling stock (e.g. light rail vehicles, tramways, streetcars, metros, commuter trains, regional trains, high speed trains, locomotives, etc.). This document focuses on: - the description of electrical interfaces for the following battery nominal voltages: 24 V, 32 V, 36 V, 48 V, 64 V, 72 V, 87 V, 96 V, 110 V; - the description of electrical interfaces: considering battery load profile and battery capacity sizing parameters (e.g. operating voltage range and charging characteristics). The main objective of this document is to achieve standardization of the electrical interfaces by considering various battery parameters in order to allow for calculating the battery capacity required for a specific load profile for the various battery technologies as detailed in the other parts of the standard.