A lift emergency system is inspected against a precise functional checklist, and its battery is expected to pass that checklist after years of doing nothing. Paper C assembles the evidence trail: the construction requirements of EN 81-20, the remote-alarm functionality tests of EN 81-28, the standby-and-talk verification that mirrors a real entrapment, the coverage of a five-party network, and the cell-level IEC 61951-2, IEC 62133-1 and UN 38.3 documentation that lets a lift manufacturer or modernisation contractor declare compliance with confidence and maintain it across periodic inspections.
EN 81-20:2014, read with the EN 81-50 design-rules standard, is the construction and installation baseline that replaced EN 81-1. Its clause 5.12.3 requires an emergency alarm device and a two-way communication system allowing permanent contact with a rescue service, with clause 5.2.1.6 addressing the alarm means in the car. These clauses establish that the communication function is a permanent, built-in safety feature - not an optional telephone - and that it must remain operational when the normal supply is absent. The emergency-power requirement is therefore implied by the very obligation to maintain the alarm and voice link through an outage.
The lift directive and national lift regulations adopt these clauses into law across the EU and in many neighbouring markets, so the battery supporting the communication system sits within the lift's safety compliance perimeter, not outside it as a mere accessory.
EN 81-28 defines the remote-alarm system and, through manufacturer test guides and inspector checklists, a repeatable functionality test. The examiner triggers the alarm with a single action and verifies that it connects automatically - no dialling by the passenger - to a permanently staffed rescue service, that two-way voice is clear in both directions, that the connection is established within about thirty seconds, that the passenger cannot terminate an established call but can re-initiate it, and critically that all of this still works with the normal power disconnected and the system running on its emergency source. Manufacturers publish step-by-step versions of this test - for example removing the power connector, checking the alarm on backup, and then removing the batteries to verify low-power behaviour.
For the battery this is a full loaded test: the auto-dialler's connection attempts, the amplifier and speaker in actual conversation, and the indicator logic must all run on the pack. A pack that holds standby voltage but sags during a GSM transmit burst will fail the very moment the test reaches 'can the passenger actually be heard'.
The quantitative verification mirrors Paper B's energy budget: with mains removed, the system must demonstrate roughly one hour of standby and at least fifteen minutes of talk - the margin prudent manufacturers double - with the audio remaining intelligible and the auto-dialler able to place and hold the call. In a five-party installation the test must additionally confirm that the car-top, pit, machine-room and duty-room stations can all communicate on backup, and that a multi-party conversation does not pull the rail below its working floor.
This is where delivered-capacity data at the real talk current and across the machine-room temperature range earns its place. A pack characterised only at a benign reference current can pass the bench and fail a cold-shaft inspection; a pack specified with an end-of-life and temperature margin passes the same test years after commissioning.
Where an automatic rescue device is fitted - required or preferred in many markets for entrapment prevention - its own test simulates a mains loss with the car away from the floor and verifies that the ARD brings it safely to the nearest landing, opens the doors and lets passengers leave, completing the sequence within the device's rated time and retaining energy for a controlled retry if needed. The battery evidence here is high-rate capability: the cells must deliver the control, brake-release and (for compact ARDs) drive current without a voltage sag that faults the controller.
High-rate, low-impedance NiMH cells are characterised for precisely this pulse duty, and IEC 61951-2 supplies the standard charge, discharge and endurance methods that frame the claim; the split architecture recommended in Paper B lets the intercom and ARD control circuits be verified independently of the main traction energy store.
Below the lift standards sit the cell-level documents. IEC 61951-2 provides the standard charge/discharge methods, charge retention and the reference endurance regime of at least 500 cycles, which - together with the illustrative fade behaviour shown, faster in cold or heat - underpins the readiness claim across a long service life. IEC 62133-1 establishes sealed-nickel safety under charging, short circuit, forced discharge and mechanical/thermal abuse, with the aqueous chemistry's forgiving, venting failure mode well suited to a device mounted in a shaft. UN 38.3 summaries and a nickel-chemistry declaration then let spare and replacement packs ship to maintenance depots without lithium-battery restrictions.
The animated fade curve is a reminder that readiness is a managed quantity: periodic inspection, gentle maintenance charging and a real capacity margin are what keep the pack at the top of the curve for the lift's whole life.
Stacked in order, the evidence is complete: EN 81-20 fixes the permanent two-way alarm obligation; EN 81-28 drives the single-action, auto-connect, thirty-second, backup-powered functionality test; the standby/talk and five-party verifications prove the energy margin; the ARD test proves the high-rate rescue; IEC 61951-2 characterises the cell; IEC 62133-1 proves its safety; and UN 38.3 clears it for shipping. A NiMH supplier that provides this documentation, matched-lot pack records and delivered-capacity curves lets the lift company clear type examination and recurring inspections with a predictable, repeatable evidence set.
Papers A through C complete the engineering case - duty, sizing and certification - for nickel-metal hydride in lift emergency rescue and communication, where a trapped passenger's ability to be heard and released is the only metric that ultimately matters.
Weijiang Power supplies certified NiMH packs for lift emergency intercoms and ARD control circuits: IEC 61951-2 capacity and endurance reports, IEC 62133-1 sealed-nickel safety evidence, UN 38.3 summaries and nickel-chemistry shipping declarations, matched welded packs with delivered-capacity curves at your talk and surge currents. Share your EN 81-28 station configuration and ARD control duty and we will assemble the evidence your lift compliance file needs.
