About this replacement
360 S10 / X100 Series — 14.4V Li-ion Replacement Battery (INR21700 M50T-4S1P)
This is a 14.4V, 5000mAh (72Wh) Li-ion battery pack for the 360 S10, X100, X100 Max, and QH100003 cordless stick vacuums. It replaces OEM part numbers INR21700 M50T-4S1P and N033-4S1P. When the original pack no longer holds a useful charge, this cell restores motor power and suction performance to the unit.
- S10 and X100 platform fitment: The S10 and X100 share the same 14.4V battery rail, connector pinout, and BMS handshake protocol. A single cell format — INR21700 M50T-4S1P in a 4S1P configuration — spans all variants in this lineup, including the X100 Max.
- Bench tested on actual hardware: We ran this pack through charge and discharge cycles on the S10 platform. The BMS communicated correctly with the vacuum's charge controller, accepted a full charge without fault codes, and delivered consistent voltage under motor load across both hard floor and carpet modes.
- Dock charging behaviour on the S10: The 360 S10 docking station does not cut power when the pack reaches full charge. Remove the vacuum from the dock once charging is complete. Leaving it docked indefinitely exposes the cells to continuous trickle current, which degrades capacity faster than normal cycle use.
Suction dropping before the battery indicator reaches low
The S10's motor controller reduces power output when cell voltage sags under load — even if the indicator still shows two or three bars. This happens when individual cells in the 4S pack are mismatched in internal resistance, causing one cell to drag the pack voltage down early. A new matched 4S1P pack eliminates the mismatch. After fitting this battery, the vacuum should maintain consistent airflow through a full cleaning session without early throttling.
Motor cutting out mid-session and recovering after a pause
This is a BMS overcurrent trip, not a dead battery. On the X100 and S10, sustained suction against a blocked filter forces the motor to draw well above its rated current. The BMS reads this as a fault and cuts the circuit to protect the cells. The pack resets after a short rest because the trip is thermal or current-based, not a hard fault. Clear the filter and check the brush roll for hair wrap before assuming the battery is at fault. If the trips continue with a clean filter, check that pack voltage at rest sits above 14.0V.