About this replacement
NextCentury TR4 Transceiver / RR4 Digital Displays — 3V Li-MnO2 Replacement Battery (CR18505)
This CR18505 lithium manganese dioxide cell is a 3V, 2500mAh replacement for the NextCentury TR4 Transceiver and RR4 Digital Displays. These modules control sensor-activated flush valves in commercial restrooms. When the original cell depletes, the solenoid loses the voltage it needs to trigger, and the flush stops responding.
- TR4 and RR4 platform fit: Both units run on the same CR18505 cell format, sharing a 3V solenoid activation circuit and identical connector housing. One cell covers both modules without modification.
- Bench tested on actual hardware: We cycled this cell through repeated solenoid trigger events and confirmed the BMS holds stable output voltage through the full activation draw spike — no premature cutoff under normal valve load.
- Post-install sensor reset: After fitting the new cell, wave a hand slowly in front of the infrared sensor three times. This runs the built-in self-test flush sequence and confirms the transceiver has accepted the new power source and re-initialised the sensor calibration.
Flusher activating randomly after a new battery is installed
Random phantom flushes after a battery swap usually point to a sensor that has not completed its power-on calibration cycle. When the cell is seated and the cover is closed too quickly, the PIR sensor can lock onto a residual thermal signature from the installer's hands. Remove the battery cover, let the unit sit for ten seconds, reseat the cell, and replace the cover without pausing in front of the sensor. If phantom triggers continue, power-cycle the unit by pulling the cell for thirty seconds before reinserting.
Flusher not activating even with a fresh CR18505 installed
If the valve does not respond after fitting a new cell, check polarity first — the CR18505 is directional and the TR4 housing gives no physical block against reverse insertion. A reversed cell reads as zero load to the control circuit and produces no error indication. Confirm the positive terminal faces the contact marked with the plus symbol inside the bay. If polarity is correct and the unit still does not fire, measure open-circuit voltage at the cell terminals — a genuine CR18505 should read 3.0V to 3.3V at rest.