About this replacement
CQR Multibox Sirens — 6V Ni-MH Replacement Battery (BAT6V-0.33A)
This is a 6V 330mAh Ni-MH rechargeable battery for CQR Multibox sirens. It slots into the siren housing as a backup power cell, keeping the siren active during mains power failure. Voltage and capacity match the OEM spec exactly — 6V, 330mAh (1.98Wh).
- Multibox siren compatibility: CQR Multibox sirens use a dedicated backup cell on a float-charge circuit. The panel trickle-charges this cell continuously so the siren stays live during a power cut. This battery sits on that same circuit and accepts the float voltage without issue.
- Bench tested on actual hardware: We ran this cell on a float-charge test rig at 6V and confirmed the BMS accepted the charge cycle without false low-battery flags. Charge acceptance was consistent across the full conditioning period.
- Float charge conditioning after installation: Do not run a zone or siren test immediately after fitting this cell. Allow 24–48 hours on float charge first. Testing before the cell is fully conditioned will cause the panel to report a low battery fault even though the battery itself is fine.
Why your alarm panel still shows low battery after fitting a new cell
CQR Multibox panels read battery state through a voltage threshold on the float-charge circuit. A brand-new Ni-MH cell sits below that threshold until it completes an initial charge cycle. The panel interprets this as a depleted battery and holds the low battery warning. Leave the panel powered and on mains for 24–48 hours — the warning clears once the cell voltage climbs above the panel's acceptance threshold, typically around 7.2V across the cell pair at rest.
Siren silent on test after backup battery swap
Some Multibox siren units apply a short inhibit window after a battery swap to allow charge stabilisation before arming the backup circuit. If you trigger a test within 30–60 seconds of installing the cell, the siren may not respond. This is a circuit-level hold, not a wiring fault. Wait at least 60 seconds after installing and closing the cover, then re-test — the siren should fire normally on the next trigger.