About this replacement
Zurn P6900-GEN / Z6913-GEN Series — 6V Li-MnO2 Replacement Battery (Flush-3 / 81846001)
This 6V, 5000mAh lithium-manganese dioxide battery replaces the Flush-3 / 81846001 cell in Zurn automatic flush valve systems. It fits the P6900-GEN, Z6912-GEN, Z6913-GEN, and Z6914-GEN sensor flush units. Li-MnO2 chemistry is the correct type for these valves — alkaline cells cannot reliably hold the solenoid activation voltage these units require.
- P6900-GEN and Z69-series valve compatibility: These models share the same battery bay, solenoid voltage threshold, and Flush-3 connector footprint. A single cell powers both the PIR sensor board and the valve solenoid, so the battery must maintain stable output across both draw levels without voltage sag.
- Bench tested on actual hardware: We cycled the solenoid repeatedly across a cold-start draw sequence and confirmed the BMS held output steady through repeated activation pulses. The cell did not trip on the inrush current the solenoid draws at activation.
- Post-install sensor reset on the Z69 series: After fitting this battery, wave a hand slowly in front of the sensor three times to trigger a self-test flush. This confirms the sensor board has accepted the new cell voltage and re-established its detection baseline — skip this and the unit may not activate on first use.
Flusher activating randomly after battery replacement
Random or ghost flushes after a battery swap usually mean the sensor board is working through an unstable startup cycle. During that window, the PIR sensor misreads ambient IR changes as occupancy events and fires the solenoid. The fix is a full power cycle: remove the battery, wait 30 seconds, and reinstall. If phantom flushes continue, hold a hand in front of the sensor until it self-test flushes, then stand clear — this forces the sensor to re-establish its ambient baseline at 6V.
Flusher not activating even with a new battery installed
If the unit will not flush after installation, confirm polarity first — the Flush-3 connector is keyed but the cell can appear seated incorrectly if the contact spring is depressed. Next, check that the replacement cell is Li-MnO2, not alkaline — alkaline 6V cells drop below the solenoid's minimum activation threshold under load. If polarity and chemistry are correct, trigger a manual flush by pressing the override button (where fitted) to confirm the solenoid is functional. A confirmed solenoid fire at 6V rules out a wiring fault and points back to the sensor board.