Ksenia Radius Indoor Siren Replacement Battery 3.7V 2000mAh

Ksenia Radius Indoor Siren — 3.7V Li-Polymer Replacement Battery (KSI7207008.000)

This 3.7V, 2000mAh lithium-polymer cell replaces the internal backup battery in the Ksenia Radius Indoor Siren and Duo wireless repeater. It maintains the siren's ability to sound during a mains power failure, keeping the alarm functional when it matters most. Voltage and capacity match the OEM spec exactly — no modifications needed.

• Radius Indoor Siren and Duo wireless repeater compatibility: Both devices share the same 3.7V Li-Polymer cell format, connector pinout, and BMS handshake protocol — a single part number covers both units without any wiring changes.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a Ksenia siren unit. The BMS accepted the cell cleanly, completed full charge without fault codes, and the siren triggered correctly on simulated alarm activation.
• Post-installation conditioning for Ksenia sirens: Do not run a zone test immediately after fitting this cell. Allow 24–48 hours on float charge before triggering a diagnostic test — the panel needs that window to accept the new cell fully, or it will flag a low-battery fault during the test even when the cell is physically fine.

Alarm panel showing low battery hours after fitting a new cell

This is a BMS reporting lag, not a faulty battery. The Ksenia panel polls the siren's battery voltage at intervals, and a freshly installed Li-Polymer cell starts below the float threshold — typically around 3.6V — until the charger circuit brings it up fully. The panel will continue to log a low-battery event until the cell crosses its acceptance threshold, which usually takes 24–48 hours of uninterrupted mains power. Leave the system powered and check panel status again after that window before assuming the cell is defective.

Siren silent on test after battery swap

A freshly installed cell can cause the siren to delay or suppress its first activation while the internal charge stabilisation cycle completes. This is a built-in protection behaviour — the siren withholds output until the cell voltage stabilises above the minimum trigger threshold. The delay is typically 30–60 seconds from power-on. If the siren still fails to sound after a full 48-hour charge period, check the tamper switch — the siren cover must seat fully or the unit stays in a fault state and will not sound.