Daitem DP 1622 D Compatible Battery 3.6V 2700mAh BAT04

Daitem DP 1622 D / L 3722 X Series — 3.6V Li-SOCl2 Replacement Battery (BAT04)

This is a 3.6V, 2700mAh Li-SOCl2 cell replacing OEM part BAT04 (also listed as D8903 and BatLi04). It fits the Daitem DP 1622 D alarm control panel and a wide range of compatible Daitem security system devices including the L 3722 X and OPT 300. Li-SOCl2 chemistry is the correct type for this panel — do not substitute alkaline or NiMH.

• Daitem DP 1622 D and L 3722 X compatibility: These panels share a common 3.6V single-cell supply rail with the same connector footprint and BMS handshake. The BAT04 reference covers all units in this series. Swapping to a different cell voltage causes the panel to flag a persistent fault code.
• Bench tested on actual hardware: We cycled this cell through a simulated panel load and confirmed the BMS accepted the new cell without fault. Open-circuit voltage measured 3.67V on delivery. The panel's charge circuit pulled the cell to float within the expected window with no tamper or low-battery flags after the conditioning period.
• Post-installation float charge period: Do not run a zone diagnostic or walk-test immediately after fitting this cell. The panel's internal charge circuit needs 24–48 hours to bring the cell to full float charge. Running a test before that window closes will cause the panel to report a low-battery warning — even with a fresh cell installed.

Why the DP 1622 D flags low battery hours after a new cell is fitted

Li-SOCl2 cells ship in a partially discharged state due to transport regulations and shelf storage. The DP 1622 D panel reads battery state via a voltage threshold, not a fuel gauge. A freshly installed cell sitting at 3.55–3.60V will sit below the panel's "full" threshold until the onboard trickle charger brings it up to float. This is normal behaviour — the flag clears automatically once float charge is reached, typically within 24–48 hours of continuous mains power.

Alarm panel loses its programmed zones after a mains power cut

If the backup cell has not yet been accepted by the panel's charge circuit, it cannot hold the RAM supply during a mains outage. The panel draws a small continuous current to maintain zone programming and the clock — if the cell voltage drops below approximately 3.2V under that load, programming is lost. Fit the new BAT04 cell, restore mains power, and allow 48 hours of float conditioning before testing backup behaviour. After that window, trigger a mains-off test and confirm the panel holds its configuration.