This is the specification that separates a signalling charger from a general-purpose one, and it is worth asking explicitly. ARTC requires the charger to supply full load with the batteries removed, and to supply the normal operating load while recharging a fully discharged battery, restoring it to at least 75% of capacity within 10 hours. Also required: the charger or the battery must each be able to be isolated without interrupting the bus-bar supply, and the no-break DC supply must hold not less than 45 V DC on a 50 V nominal system. Ripple is specified at 1% or less.
AS 7703 clause 4.2.3 sets the method: battery storage shall be calculated to ensure power is available for the total period required, accounting for the maximum contiguous cloudy days at that location, battery capacity degradation over service life, and availability and reliability calculations. In practice that means three things a generic solar calculation omits: use the worst-month solar resource for that latitude, size to end-of-life capacity rather than nameplate, and apply the temperature derating for the location case rather than for ambient. A site that only just meets its autonomy requirement when new will not meet it in year eight.
It is usually the dominant factor, and it is under-modelled. A signalling location case is a sealed metal enclosure in the sun; internal temperatures well above ambient are normal. VRLA life expectancy falls roughly 50% for every 10 °C sustained above 20 °C, so a 10-year design-life battery in a 40 °C location case is a 2.5-year battery, and the capacity lost to heat cannot be recovered. Note that AS 7720 addresses internal temperature control and ventilation for signalling equipment enclosures for exactly this reason. Measure the case temperature in February before specifying the battery.
ARTC’s DC power supply specification already requires chargers with network connectivity, a web interface, laptop diagnostics and fault and alarm management, so the monitoring path usually exists before anyone specifies monitoring. What it does not usually provide is cell-level condition data. There is currently no AS 7000-series clause mandating remote battery bank monitoring. It is specified project by project and through charger and RTU requirements. The operational case is the same as everywhere else on a rail network: a fault diagnosed remotely is a planned visit inside a possession window; a fault discovered on site is an unplanned one.
Yes, for the specified products. Transport for NSW Asset Standards Authority Type Approval TA 8045.1:2025, “Valen Power – 12 Volt Batteries”, covers the ENVIROX-CELPLUS Carbon Front Terminal range in 100 Ah, 170 Ah and 190 Ah (12EO+FT100, 12EO+FT170, 12EO+FT190). Discipline: Signals and control systems. Mode: Rail (Heavy Rail). Effective 8 December 2025.
This matters more than it may appear, because rail procurement runs a type approval gate on top of the national standards. A product can comply with every applicable standard and still be unacceptable if it is not on the relevant infrastructure manager’s approved materials register. ARTC, for example, requires prototype approval and factory acceptance testing for new or modified designs, and states a procurement preference for products already proven in similar signalling applications.
Practical advice if you are a contractor mid-tender: confirm the register entry before you price the product, and check which edition of each standard the specification cites, several rail and road authority specifications still reference superseded editions.
AS 7703, the national railway signalling power supply standard, sets the conventions: 50 V DC for signalling logic and interlockings, 24 V DC for electronic equipment, 12–15 V DC for level crossing and legacy equipment, and 110/120 V AC for main distribution. ARTC’s level crossing standard specifies 12 V and/or 18 V nominal DC systems with 240 V single-phase AC. Individual rail infrastructure managers add their own network standards on top, so the governing document for any given site is the RIM’s functional specification, not the national standard alone.
For active level crossings, the most quotable Australian figure is from ARTC ESC-03-01 clause 5.3: batteries must operate the level crossing protection, control and train detection equipment, plus any signalling fed from that location, for a minimum of 48 hours with 10% residual capacity under average traffic densities. Note two subtleties that affect sizing: the 48 hours covers the whole location’s load, not just the flashing lights, and the 10% residual means design capacity is effectively 48-hour load ÷ 0.9 before temperature and ageing derating. For other signalling assets, run time is project-specific, ARTC’s signalling power standard states it is defined for each project in the functional specification.
NiCd tolerates a wider temperature range, deep discharge and long neglect better, which is why it persists in legacy signalling installations. Sealed gel VRLA is lower cost, needs no watering, is easier to handle and dispose of, and is explicitly permitted. The pragmatic position most Australian RIMs have reached is that sealed long-life cells should be used wherever possible, which is ARTC’s own wording, with NiCd retained where a specific installation or approval requires it. The deciding factors on a new installation are usually location-case temperature and the maintenance regime, not chemistry preference.
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