oSIST prEN IEC 62973-1:2025/oprAA:2026

oSIST prEN IEC 62973-1:2025/oprAA:2026 is a CENELEC draft amendment to the European standard for railway applications - rolling stock batteries for auxiliary power supply systems, Part 1: General Requirements. It adds European requirements on environmental conditions, preferred system voltage, fire protection, external electrical connections, transport information and testing, so manufacturers, integrators and test labs know what to apply in European railway projects.

What does oSIST prEN IEC 62973-1:2025/oprAA:2026 specify?

oSIST prEN IEC 62973-1:2025/oprAA:2026 specifies European additions to the base Part 1 standard for auxiliary batteries used on railway rolling stock. The amendment focuses on the conditions and interfaces that matter in European use, especially voltage, climate, fire safety and transport.

The document is structured as a European foreword, then ten amendment clauses that modify specific clauses of the base standard, followed by bibliography changes. The modification points are:

• Clause 2 - normative references
• Clause 3.2 - abbreviated terms
• Clause 4.3 - environmental conditions
• Clause 4.4.1 - system voltage
• Clause 4.4.3.4 - low or high temperature performance
• Clause 4.6 - fire protection
• Clause 6.2 - external electrical connections interface
• Clause 8.1 - transportation
• Clause 9.2.5 - shock and vibration test
• Bibliography updates

What are the key requirements of oSIST prEN IEC 62973-1:2025/oprAA:2026?

oSIST prEN IEC 62973-1:2025/oprAA:2026 tightens the European-facing requirements for battery systems by linking them to railway environmental, fire and test standards. In practice, it tells suppliers what conditions to design for and what to document or verify.

Environmental conditions and voltage

Clause 4.3 ties ambient temperature and humidity to EN 50125-1. For ambient temperature, the amendment points to T3, and it allows deviations only by agreement between the end user or system integrator and the cell or battery manufacturer. This matters because the battery is being designed for a defined railway climate rather than a generic indoor environment.

Clause 4.4.1 states that the preferred system voltage of the low voltage supply network is 110 V, including tolerances, according to one of the recommended voltages in EN 50155. That gives designers and buyers a clear preferred electrical interface for the auxiliary power network.

Low-temperature performance and fire protection

Clause 4.4.3.4 adds a low-temperature discharge condition. The battery must still supply the required deep temperature load profile at -18 °C, or at another agreed temperature. This is important for cold-weather service because it links the battery's charged state to its real duty under cold conditions.

Clause 4.6 requires the battery system to comply with the EN 45545 series for railway vehicle fire safety, and also to consider the safety standards for the technologies and integration used. The note says fire protection may be achieved at cell, monobloc, tray or box level, so the design team must show how the chosen construction meets the fire-safety approach.

Interfaces, transport and testing

Clause 6.2 requires the battery system to be designed so that the positive and negative main terminals, and tray terminals, cannot be mixed up or easily short-circuited. This is a practical installation and maintenance safeguard.

Clause 8.1 requires the battery manual to include the valid national regulations and transportation rules for batteries and defect batteries. Clause 9.2.5 extends the shock and vibration test to include float charging operation, which means the test must represent the charging state used in service, not only a static battery condition.

What terms does oSIST prEN IEC 62973-1:2025/oprAA:2026 define?

The amendment adds or uses a small set of technical terms that are central to its application:

• LVPS - Low Voltage Power Supply, the low-voltage supply network for the battery system.
• T3 - the ambient temperature category referenced from EN 50125-1 for rolling stock equipment.
• Deep temperature load profile - the low-temperature duty the charged battery must still supply.
• EN 45545 - the railway fire protection series applied to the battery system.
• Float charging operation - charging mode that must be considered in shock and vibration testing.
• Tray terminals - battery tray terminals that must not be confused with the main positive and negative terminals.
• System voltage - the voltage level of the low voltage supply network, with 110 V preferred here.

Who uses oSIST prEN IEC 62973-1:2025/oprAA:2026?

Battery manufacturers, rolling stock builders, system integrators and railway equipment suppliers use this amendment when designing auxiliary power batteries for railway vehicles. Test laboratories and conformity assessment teams use it to select the correct environmental, fire and vibration conditions.

End users and quality or procurement teams use it to check whether a proposed battery system matches the expected railway voltage, climate, fire safety and transport documentation. The amendment also speaks directly to agreement points between the end user, system integrator and cell or battery manufacturer.

What changed in oSIST prEN IEC 62973-1:2025/oprAA:2026 from the previous edition?

oSIST prEN IEC 62973-1:2025/oprAA:2026 modifies prEN IEC 62973-1:2025 by adding European references and requirements for:

• EN 50125-1 in normative references
• EN 45545 (all parts) in normative references
• LVPS in abbreviated terms
• T3 ambient temperature and humidity conditions
• preferred 110 V system voltage
• low-temperature discharge at -18 °C
• fire protection linked to EN 45545
• polarity protection at battery and tray terminals
• transportation information for batteries and defect batteries
• float charging operation in the shock and vibration test
• EN 50155 in the bibliography

Which standards are used with oSIST prEN IEC 62973-1:2025/oprAA:2026?

What does the oSIST prEN IEC 62973-1:2025/oprAA:2026 document contain?

The document contains the European foreword, a contents page, and the amendment text that replaces or adds specific wording in the base standard. It shows exactly which clauses are updated and how the European additions fit into the original Part 1 structure.

For a technical reader, the useful content is the clause-by-clause change set: environmental conditions, system voltage, low-temperature performance, fire protection, external electrical connections, transport instructions, shock and vibration testing, and bibliography updates. That is the material needed to compare the base standard with the European requirements and apply them in design, testing and documentation.