Roborock F25 21.6V Replacement Battery BCR-61P-4000TS

Roborock F25 / F25 LT / F25 RT — 21.6V Li-ion Replacement Battery (BCR-61P-4000TS)

This is a 21.6V, 4000mAh (86.4Wh) lithium-ion battery for the Roborock F25, F25 LT, and F25 RT robot vacuum. It replaces OEM part BCR-61P-4000TS directly. The F25 series uses this cell pack to drive the suction motor, brush roll, and navigation system through full autonomous cleaning cycles.

• F25, F25 LT, F25 RT compatibility: All three variants share the same 21.6V voltage rail, BCR-61P-4000TS connector layout, and BMS handshake protocol. Swapping between them is not needed — this single cell pack covers the full F25 lineup.
• Bench tested on actual hardware: We ran this pack through charge and discharge cycles on the F25 platform. The BMS communicated charge state correctly to the dock, reported cell voltage accurately to the app, and did not trigger false low-battery cutoffs under normal suction loads.
• Dock charging protocol for the F25: Do not leave the F25 sitting on the charging dock indefinitely between uses. Continuous dock contact keeps the BMS in a trickle-charge state that accelerates cell degradation. Charge to full, then lift the unit off the dock until the next session.

Suction dropping before the F25 battery indicator reaches low

The F25 suction motor draws significantly more current when airflow is restricted — a partially blocked filter or full dustbin forces the motor to compensate, pulling current above the BMS's sustained-draw threshold. The BMS responds by reducing output voltage to protect the cells, which the vacuum interprets as a low-charge state even when capacity remains. The result is a noticeable suction drop while the app or indicator still shows a mid or high charge level. Clean the filter and empty the dustbin first — if suction recovers immediately, the battery is not the cause.

F25 not powering on after battery sits unused for several weeks

Li-ion cells self-discharge at roughly 2–3% per month under storage conditions. If the F25 sits unused for an extended period and cell voltage drops below approximately 2.5V per cell, the BMS enters a deep-discharge protection state and will not pass current to the motor or dock communication pins. Place the unit on the charging dock and leave it connected for at least 90 minutes without interruption — the BMS requires a low-current recovery phase before it will accept a full charge cycle. If the dock LED does not respond after 2 hours, check that dock contact pins are clean and making firm contact with the robot's charge terminals.