Does AS/NZS 5139 apply to a stand-alone power system?

Sometimes, and the exclusions are the part most people get wrong. AS/NZS 5139:2019 applies to battery systems used with power conversion equipment between 12 V and 1500 V DC with a capacity of at least 1 kWh and no more than 200 kWh. It expressly excludes:

• telecommunications applications
• uninterruptible power systems complying with AS 62040
• premises with critical power continuity requirements, such as acute care hospitals
• electric vehicles, portable equipment and transportable structures

So a 55 kWh SAPS serving a rural property is generally in scope. A battery bank at a telecommunications site is not. A UPS battery in a data centre is not. Where 5139 does not apply, the standards that do are different, AS 3011 for secondary batteries installed in buildings, AS 2676 for their installation, maintenance and testing, AS 4044:2024 for the charger, and AS 60896.22:2023 for valve-regulated lead-acid product requirements.

Amendment 1 (2025) added material worth knowing if you are designing an enclosure or a room: a formal “battery room” definition requiring a dedicated room, a garage or storeroom does not qualify, new clearance figures including 600 mm at the front and 900 mm above in restricted locations, and a new appendix for calculating cell short-circuit current.

We answer this in detail because getting it wrong in either direction is expensive: applying 5139 where it does not belong adds cost and delay, and missing it where it does apply fails inspection.