About this replacement
Dreame X40 Master / RLX73CE — 14.4V Li-ion Replacement Battery (R2416-4S2P-XDEV)
This is a 14.4V, 5200mAh Li-ion replacement battery for the Dreame X40 Master and RLX73CE cordless stick vacuum. It replaces OEM part R2416-4S2P-XDEV, which powers both the motorized brush head and the suction motor. Fit it when the original cell no longer holds enough charge to complete a full cleaning session.
- X40 Master and RLX73CE compatibility: Both models share the same 14.4V battery rail, connector pinout, and BMS handshake protocol — the same cell pack covers both. Swapping between them requires no adapters or firmware changes.
- Bench tested on actual hardware: We ran this pack through a full charge cycle and measured cell balance at completion. The BMS held all four cells within 20mV of each other at full charge, and overcurrent cutoff triggered correctly under a simulated blockage load without latching off permanently.
- Dock charging habit on the X40 Master: Do not leave the X40 Master sitting on the charging dock continuously. Trickle current from permanent dock contact accelerates capacity fade on Li-ion packs in this voltage class. Charge to full, then remove the vacuum from the dock until the next use.
Cordless vacuum losing suction before the battery indicator reaches low
This happens when the motor draws more current than the BMS expects at a given state of charge. A partially blocked filter or tangled brush roll forces the motor to pull harder, increasing current draw and causing the BMS to sag output voltage early. The vacuum feels like it is running out of charge when the actual issue is elevated load. Clear the filter and brush roll first — if suction returns to normal, the battery is not the cause.
Motor cuts out mid-clean then recovers after a short pause
This is a BMS overcurrent trip, not a dead cell. When the suction path is restricted — blocked filter, compacted debris in the cyclone, or a jammed brush head — the motor stalls briefly and current spikes above the BMS trip threshold. The BMS cuts power to protect the cells, then resets once current drops. Clean the filter and check the brush roll for obstructions. If the cutout stops after clearing the blockage, the pack is functioning correctly; if it persists on a clean machine, measure resting voltage — a healthy pack at full charge should sit at approximately 16.8V.