IEC 62973-4-2021 pdf Railway applications – Rolling stock – Batteries for auxiliary power supply systems – Part 4: Secondary sealed nickel-metal hydride batteries

4.2 Definition of battery type General 4.2.1 A battery consists of a number of cells or battery modules and/or assembled in trays, crates, and then assembled in a battery box. A cell consists of positive and negative plates, electrolyte, metal container and sealing cap. Positive and negative terminals, which are apart by a separator, are housed and sealed in the metal container with a sealing cap. The sealing cap consists of a positive terminal, a pressure release valve and an insulator which are insulated to a negative part that forms a container. The container wears an insulating envelope. The positive active material is nickel hydroxide, and the negative active material is hydrogen absorbed nickel-alloy. The electrodes are surrounded by electrolyte, an aqueous solution mainly of potassium hydroxide (KOH), and distilled or deionized water. The electrolyte does not chemically change or degrade due to charge/discharge cycles.
The interface system between the battery charging system and the battery box as shown in Figure 4 consists of: a) Battery voltage sensing and regulation; maximum ±1 % tolerance (see (1) in Figure 4); b) Temperature data acquisition, (2a), including wiring (2b) to the sensor (3); typically, better than ±2,5 K tolerance; c) Temperature sensor (3): maximum tolerance ±2 K for the specified temperature range preferably attached to the battery, minimum one sensor per battery system (see (3)); The choice of the temperature sensor shall be agreed between the system integrator and the suppliers of the battery and battery charging system; d) Position of the temperature sensor (3) within the battery box (4); e) Cabling between battery and battery charger; part of system integration in the rolling stock (5). The system integrator will check if and how the effect of the wiring needs to be compensated, considering voltage drop in the power cables and resistance in the temperature sensor wires. The impact of the sensor wiring depends on the type of temperature sensor, data acquisition system and/or location of the voltage sensor. If there are significant influences, it is possible to compensate these influences in the battery charger control system upon agreement between the system integrator and the manufacturer of the battery charging system. With the recommended temperature sensors, the influence of the wiring resistance on the temperature acquisition can be neglected.