Xiaomi Viomi Cyber 25.9V Replacement Battery JS-WV02A02

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

This is a 25.9V 2400mAh Li-ion battery for the Xiaomi Viomi Cyber and Viomi Cyber Lite cordless stick vacuums. It replaces OEM part JS-WV02A02. Capacity is 62.16Wh — identical to the factory specification for both models.

• Viomi Cyber and Cyber Lite compatibility: Both models run the same 25.9V battery rail and use the same JS-WV02A02 connector and BMS handshake. The pack communicates cell state to the vacuum's main board — the replacement cell matches that communication protocol.
• Bench tested on actual hardware: We cycled this pack through repeated charge and discharge sequences on the Viomi Cyber platform. The BMS responded correctly to charge termination and did not trip on motor-start inrush. Cell voltage at full charge measured 29.4V across all test units.
• Dock charging habit on the Viomi Cyber: Do not leave the vacuum sitting on the charging dock permanently. Continuous trickle charging accelerates capacity fade in the Li-ion cells faster than normal use does. Charge to full, then remove the vacuum from the dock until the next clean.

Suction dropping before the battery indicator reaches low on the Viomi Cyber

This is a voltage sag issue, not a capacity issue. When the motor encounters resistance — a partially blocked filter, a thick carpet, or a dense dust load — it draws more current than the cells can deliver at stable voltage. Voltage sags under that load, the main board reads it as low battery, and the vacuum reduces motor speed to protect itself. Clean the filter first. If sag continues after filter cleaning, the original battery's cells have degraded and internal resistance is too high to sustain motor current — this replacement pack restores the lower internal resistance needed to hold voltage steady under load.

Motor cuts out mid-clean then comes back after a few seconds

This is a BMS overcurrent trip, not a power switch fault. The BMS monitors current draw and cuts the output circuit when sustained current exceeds its threshold — typically triggered by restricted airflow forcing the motor to work harder. The BMS resets automatically after a few seconds, which is why the vacuum restarts on its own. Check the filter and brush roll for blockages before assuming the battery is at fault. If the cutout still happens on a clear filter with this replacement pack installed, the motor itself may be drawing above its rated current and needs service.