About this replacement
Shark VM252 / VM252C / QM250 — 10.8V Li-ion Replacement Battery (XBAT CMT4)
This is a 10.8V 1900mAh lithium-ion battery for the Shark VM252, VM252C, and QM250 cordless stick vacuums. It replaces part number XBAT CMT4 directly. When the original cell loses capacity and suction weakens before the indicator hits low, this is the part that restores normal motor voltage.
- VM252, VM252C, and QM250 compatibility: These three models share the same 10.8V battery platform, connector layout, and BMS handshake protocol — one cell fits all three without modification.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a VM252 unit. The BMS engaged correctly at charge termination, and the protection circuit tripped at expected overcurrent thresholds under load simulation.
- Dock charging behaviour on the VM252 series: Do not leave the vacuum sitting on the charging dock continuously. These vacuums trickle-charge when docked and full, which accelerates capacity fade in lithium cells. Charge to full, then remove from the dock until the next use.
Suction dropping before the battery indicator reaches low
The VM252 motor draws higher current when airflow is restricted — a partially blocked filter forces the motor to work harder, pulling the cell voltage down faster than the indicator circuit expects. The indicator reads state-of-charge, not motor load, so suction can degrade significantly while the display still shows partial charge. Clean or replace the filter first. If suction then holds steady, the battery is not the root cause. If suction still drops early with a clean filter, the cell has lost enough capacity that voltage sags under normal motor load — swap the battery.
Motor cuts out mid-clean then recovers after a short pause
This is a BMS overcurrent trip, not a motor fault. When the filter is restricted or a blockage increases resistance in the airpath, the motor draws sustained current above the BMS protection threshold and the circuit cuts power. After a brief pause, the BMS resets and the vacuum starts again. Check the filter and clear any blockage in the nozzle or hose before assuming the battery is faulty. If the cutout persists with a clear airpath, verify the cell is fully charged — a low cell hits the BMS trip threshold faster under load. Charge fully to 12.6V before testing again.