Cecotec Conga Rockstar 900 Replacement Battery 29.6V 3000mAh

Cecotec Conga Rockstar 900 Series — 29.6V Li-ion Replacement Battery (84776)

This 29.6V 3000mAh Li-ion battery replaces OEM part 84776 in the Cecotec Conga Rockstar 900, 901, Rockstar 3000 IA, 9500 Connected 3000 IA, and over 28 additional Conga Rockstar models. It fits the robotic vacuum's battery bay and connects to the same BMS handshake the original cell used. Voltage and capacity match factory spec exactly — 29.6V, 3000mAh, 88.8Wh.

• Rockstar 900 series compatibility: These models share a common 29.6V battery platform with the same physical connector, bay dimensions, and BMS communication protocol. Swapping cells across this line works because the charging circuit and cutoff thresholds are identical across the range.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on a Conga Rockstar unit and confirmed the BMS handshake initialised correctly, cutoff voltage held at the expected low-cell threshold, and charge acceptance reached rated capacity without thermal events.
• Dock charging habit for the Rockstar platform: Do not leave the Conga Rockstar sitting on the charging dock continuously between uses. The Rockstar's dock delivers a trickle charge once full, and sustained trickle charging degrades Li-ion cell capacity measurably faster than charge-then-remove cycles. Charge to full, then lift the unit off the dock.

Suction dropping before the battery indicator reaches low on the Rockstar 900

This happens because the Rockstar's motor draws significantly more current when the filter is partially blocked or the brush roll is restricted. That extra draw causes the cell voltage to sag under load, triggering the BMS to reduce power delivery before the state-of-charge indicator catches up. The indicator reads remaining capacity at rest, not under load — so the gap between perceived charge and actual motor performance widens fast when airflow is restricted. Check and clean the filter first; if suction recovers, the battery is not the cause.

Motor cuts out mid-cycle then restarts a few seconds later

This is a BMS overcurrent trip, not a dead battery. When suction is blocked — by a clogged filter, tangled brush roll, or debris jam — the motor draws above its rated current to maintain airflow, and the BMS cuts power to protect the cell. After a few seconds the BMS resets and the motor restarts. Remove the filter, clean it fully, and clear any brush roll obstruction. If the fault stops after cleaning, the battery is functioning correctly; if it persists on a clear filter, verify the replacement cell's BMS trip threshold matches the 29.6V platform spec.