Dialler 442-29 X Replacement Battery 3.7V 700mAh

Dialler 442-29 X / 450-29 X / 470-29 X / 485-21 X — 3.7V Li-ion Replacement Battery

This is a 3.7V 700mAh Li-ion cell for Dialler wireless alarm panels and security system transmitters across the 442-29 X, 450-29 X, 470-29 X, and 485-21 X series. It slots in as the internal backup cell that keeps the panel live during a mains power failure. Capacity is 700mAh (2.59Wh), matching the original factory specification.

• Four-model compatibility: The 442-29 X, 450-29 X, 470-29 X, and 485-21 X share the same 3.7V cell footprint, connector pinout, and charge management circuit. Swapping between these panels uses the same physical cell — the BMS in each model pulls the same float voltage and cutoff threshold.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Dialler-compatible panel test rig. The BMS accepted the cell without fault codes, floated correctly at 4.2V, and the low-battery flag cleared after a full charge cycle.
• Post-installation wait before zone testing: Do not run a diagnostic zone test immediately after fitting this cell. Allow 24–48 hours on float charge first. The panel's charge controller needs time to fully condition the new cell — testing too early will trigger a false low-battery report on the panel display.

Alarm panel losing programming during a power outage after fitting a new cell

A freshly installed Li-ion cell may not yet hold enough charge to sustain panel memory through a full mains outage. The panel backup circuit requires the cell to reach a minimum state of charge — typically above 3.6V — before it will commit to supplying RAM-hold current. If the mains drops before the cell has conditioned, the panel can lose zone assignments, user codes, or event logs. Leave the panel connected to mains for at least 48 hours after fitting the new cell before cutting power for any test.

Siren not sounding during a test trigger after battery replacement

Dialler panels impose a charge-stabilisation delay on the siren output when a new backup cell is detected. The siren circuit monitors cell voltage and holds the output muted for 30–60 seconds after the panel boots with a fresh cell. Triggering a test alarm in that window produces no sound — the panel logs the event but suppresses the siren. Wait at least two minutes after powering the panel with the new cell, then re-run the test trigger. If the siren still does not activate, confirm the cell voltage reads 3.7V or above before investigating the siren wiring.