About this replacement
Daitem SH156AX — 3V Li-MnO2 Replacement Battery (RXU15X)
This is a 3V lithium-manganese dioxide cell rated at 3000mAh (9Wh), direct replacement for the Daitem SH156AX wireless transmitter. It powers the sensor's radio module and keeps communication live between the perimeter device and the main alarm control panel. OEM part number is RXU15X.
- SH156AX transmitter fit: The SH156AX uses a fixed 3V Li-MnO2 rail to drive low-power RF transmission bursts. This cell matches the voltage, physical dimensions (66.20 × 28.60 × 14.20mm), and discharge curve the transmitter's onboard circuit expects. Fitting a different chemistry or voltage breaks the supervisory signal.
- Bench tested on actual hardware: We ran this cell against the SH156AX transmitter circuit and confirmed stable 3V output across the load. The BMS accepted the cell without triggering a false tamper or low-battery flag after the initial 24-hour float period.
- Post-installation supervision window: Do not run a zone or walk-test immediately after fitting this cell. The panel's supervisory polling can misread the new cell as low-voltage during the first stabilisation period. Allow 24–48 hours before initiating any diagnostic test to avoid a false low-battery report.
Why the SH156AX still shows low battery hours after a fresh cell is fitted
The Daitem panel polls each wireless zone on a timed supervisory cycle. When a new Li-MnO2 cell is installed, the transmitter's internal voltage stabilises over several hours as the cell settles under load. If the panel polls during this window, it may log a low-battery event even though the cell is fully intact. This is a timing artefact, not a fault. Wait the full 24–48 hours, then clear the event log from the panel — the flag will not return if the cell is correctly fitted.
Tamper fault appearing on panel immediately after battery swap
A tamper fault on the SH156AX almost always means the sensor casing was not fully closed after accessing the battery compartment. The transmitter has a physical tamper switch that reports to the panel the moment the lid seal breaks. Re-open the unit, seat the new cell, and press the cover firmly until the retaining clips engage. Confirm the panel clears the tamper flag — if it persists, check that no part of the cell is obstructing the lid's full closure.