Daitem SC200AU Replacement Battery 3.7V 700mAh 908-21X

Daitem SC200AU / SC201AX Controllers — 3.7V Li-ion Replacement Battery (908-21X)

This 3.7V, 700mAh Li-ion cell replaces the internal battery in Daitem wireless alarm controllers and sender modules. It fits the SC200AU, SC201AX, Sender GSM G470-30, DP8000, and more than 17 additional Daitem units. Use the OEM part numbers 908-21X or BAT90821 to confirm fitment before ordering.

• SC200AU / SC201AX platform fit: These controllers share the same 3.7V single-cell architecture, connector footprint, and BMS handshake protocol. One cell covers the full controller range without modification.
• Bench tested on actual hardware: We ran this cell through a full charge cycle and monitored BMS communication with the host unit. The cell accepted charge without fault flags and reported state-of-charge correctly to the panel within the expected window.
• Post-swap float charge requirement: Do not trigger a zone test immediately after fitting this cell. Allow 24–48 hours on float charge before running any diagnostic. A cell installed below float voltage will cause the panel to report a low battery fault even though the hardware is functioning correctly.

Alarm panel showing low battery hours after installing the new cell

A freshly installed Li-ion cell often sits below the panel's accepted float threshold — typically around 3.9–4.0V — when it arrives from storage. The Daitem BMS reads state-of-charge continuously and will flag a low battery condition until the cell reaches full float. This is not a faulty cell. Leave the panel powered for 24–48 hours and the fault will clear once the cell charges past 4.1V.

Panel loses saved programming during a mains power outage after battery replacement

If the replacement cell has not completed its initial charge cycle, it may not hold enough capacity to sustain panel memory through a mains dropout. The SC200AU draws a small but continuous standby current, and an undercharged cell can drop below the cutoff threshold quickly under that load. This wipes volatile memory before the mains returns. Allow a full 48-hour conditioning period on mains power after fitting the new cell before testing backup behaviour.