Viomi Cyber Lite 25.9V Cordless Vacuum Replacement Battery

Viomi Cyber Lite / Cyber — 25.9V Li-ion Replacement Battery (JS-WV02A02)

This 25.9V 2400mAh (62.16Wh) lithium-ion battery replaces the original JS-WV02A02 pack in the Viomi Cyber Lite and Cyber cordless stick vacuums. It slots into the same battery housing, connects to the same BMS handshake points, and restores full motor voltage to the cleaning head. Capacity matches the rated spec — 2400mAh at 25.9V nominal.

• Cyber Lite and Cyber platform fit: Both models share the same 25.9V battery rail, identical connector pinout, and the same BMS communication protocol. One replacement cell covers both units without modification.
• Bench tested on actual hardware: We ran this cell through the Cyber Lite's charge cycle and confirmed the BMS handshake completed correctly. The protection circuit tripped at the expected overcurrent threshold during simulated blockage loads and reset cleanly on restart.
• Dock charging on cordless vacuums: Do not leave the vacuum sitting on the dock permanently. Continuous trickle charging accelerates capacity fade in lithium cells at this voltage. Charge to full, then remove from the dock until the next use.

Motor cutting out mid-clean on carpet — what's actually happening

Thick carpet fibres restrict airflow through the brush head and force the motor to draw more current than its rated load. The BMS detects an overcurrent condition and cuts power to protect the cell. This is not a battery fault — it is the protection circuit doing its job. If the vacuum restarts after a few seconds but cuts out again, check the filter and brush roll for blockage before assuming the battery is faulty.

Suction dropping well before the battery indicator shows low

This is voltage sag — when the cell's internal resistance rises, voltage drops under motor load even though the state-of-charge reading looks healthy. A partially clogged filter compounds the problem by forcing the motor to work harder, which deepens the sag further. The indicator reads resting voltage, not load voltage, so it lags the real picture. Clean the filter first; if sag persists after a full charge cycle, the cell has degraded and replacement is the correct fix.