About this replacement
ROOMZ Room Sensor — 3V Li-MnO2 Replacement Battery (CP505050)
This 3V, 3000mAh Li-MnO2 cell replaces the CP505050 battery inside ROOMZ room sensors. These sensors monitor occupancy, temperature, and air quality in meeting spaces, feeding data to building management and conferencing systems. The flat prismatic format — 50.80 x 48.00 x 4.80mm — fits the sensor housing without modification.
- ROOMZ sensor platform: ROOMZ room sensors run a continuous wireless reporting loop alongside onboard environmental monitoring. Both draws share the same 3V cell, so the battery must hold a stable voltage curve across combined low-level loads without sagging prematurely.
- Bench tested on actual hardware: We ran CP505050 cells under a simulated dual-load profile — wireless transmission bursts plus steady sensor polling. The BMS held the output rail within spec across the full discharge curve, with no unexpected cutoff events during the wireless burst cycles.
- First-session calibration: After swapping this cell, let the sensor run through one full reporting cycle before trusting the battery indicator. ROOMZ sensors map battery state against voltage thresholds during normal operation, and the indicator can read inaccurately in the first session after a fresh install.
Why the battery indicator reads wrong after a CP505050 swap
ROOMZ sensors track battery state by comparing the current cell voltage against stored thresholds built up during previous discharge cycles. A brand-new Li-MnO2 cell starts at the top of its voltage curve — typically around 3.0V open circuit — which the sensor firmware may not map correctly until it observes a full operating cycle. During the first session, the indicator may show a low or erratic reading even though the cell is fully charged. Allow the sensor to run through one complete reporting period, and the display will recalibrate to the actual cell state.
Sensor stops transmitting data mid-session after battery install
If the sensor drops off the network shortly after a battery swap, voltage sag under the combined wireless and environmental sensing load is the likely cause. Li-MnO2 cells are sensitive to contact resistance at the terminal interface — even a slight misalignment on the flat prismatic contacts can cause a voltage dip during transmission bursts, triggering the BMS protection circuit. Remove the cell, wipe the battery contacts clean with a dry cloth, and reseat firmly. If the issue persists, check that the cell is seated flush against both contact pads, with no tilt — the 4.80mm thickness spec leaves little tolerance in the housing.