About this replacement
Cecotec Conga 8090 Series — 14.4V Li-ion Replacement Battery (U099-4S1P)
This is a 14.4V, 6800mAh Li-ion replacement battery for the Cecotec Conga 8090, Conga 8090 Ultra, Conga 8090 Ultra T, and Conga 8090 Ultra X robotic vacuum cleaners. It slots into the same bay as the original and connects via the same OEM-spec connector. Capacity is 6800mAh — use the figures above, not third-party listings.
- Conga 8090 platform fit: All variants in this line — 8090, 8090 Ultra, 8090 Ultra T, and 8090 Ultra X — run the same 14.4V architecture and share the U099-4S1P battery format. The BMS handshake, cell count, and connector are identical across the range, so one SKU covers all of them.
- Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on a Conga 8090 unit. The BMS negotiated correctly, the unit accepted charge without fault codes, and the motor drew current within the expected range across both hard floor and carpet load profiles.
- Dock charging habit on the Conga 8090: This robot's charging dock applies a trickle current once full rather than cutting off entirely. Leaving it docked continuously accelerates capacity fade in the cell. Charge to full, then remove the robot from the dock until the next cleaning cycle.
Suction dropping before the battery indicator shows low
The Conga 8090 motor draws significantly more current when the filter is partially blocked or the intake path is restricted. Under that load, the cell voltage sags earlier than the battery indicator expects, so the robot behaves as if it is running low when the charge gauge still reads mid-level. The BMS reads actual cell voltage, not the displayed estimate. Clean the filter and check the intake path — if suction recovers and the robot completes its run, the battery is fine and the restriction was the cause.
Motor cuts out mid-run then recovers after a short pause
This is a BMS overcurrent trip, not a dead cell. It happens when the motor sustains a higher-than-rated draw — usually because a blocked filter forces it to work harder to maintain airflow. The BMS cuts power to protect the cells, then resets once the draw drops. The fix is not a new battery. Clear the filter, check for debris wrapped around the brush roll, and confirm the intake is clear. If the motor runs without cutting out after that, the trip was load-driven, not a battery fault.