Daitem BATLI28 3V Alarm System Replacement Battery 2400mAh

Daitem 186-21X Series — 3V Li-MnO2 Replacement Battery (BATLI28 / BATLI38)

This is a 3V lithium manganese dioxide backup cell rated at 2400mAh (7.2Wh), sourced to the BATLI28 and BATLI38 specifications. It fits the Daitem 186-21X alarm panel and a wide range of compatible Daitem security system control panels including the DP8264X, 26021X, and DP8262W. This cell takes over when mains power drops, holding alarm functionality, zone memory, and emergency signalling active.

• 186-21X and DP82-series compatibility: These panels share the same 3V backup rail, BATLI28/BATLI38 connector footprint, and BMS handshake logic. The cell slots into the same tray across all listed models — no adapters or wiring changes required.
• Bench tested on actual hardware: We ran this cell under simulated mains-loss conditions. The BMS accepted charge cleanly, voltage held steady at 3V across the float cycle, and no low-battery fault codes were triggered after the 48-hour conditioning window.
• Post-installation zone testing: Do not run a diagnostic test immediately after fitting this cell. The panel float-charges the new cell over 24–48 hours before the BMS reports a full state. Triggering a zone test before that window closes can return a false low-battery fault on the panel display.

Why the Daitem 186-21X still reports low battery after a fresh cell swap

The 186-21X panel does not read the cell's raw terminal voltage directly — it polls the BMS charge state after a conditioning window. A brand-new BATLI28 cell measures close to 3V on a meter, but the panel's internal threshold check won't clear until the float charge cycle completes. This typically takes 24–48 hours on a powered panel. Cutting that window short by running a test or cycling the panel will reset the timer and extend the fault period.

Alarm panel loses zone programming during a power outage after battery replacement

If the panel drops its zone configuration during a mains failure shortly after a battery swap, the replacement cell has not yet been accepted into active backup duty. The panel requires a full conditioning cycle — typically 48 hours of mains-powered float charge — before it hands off memory retention to the new cell. Swapping the battery and then testing with a mains cut the same day bypasses this window entirely. Restore mains power, allow a full 48-hour charge cycle, then retest the backup scenario.