Cecotec Conga 8090 Ultra Replacement Battery 14.4V 6700mAh

Cecotec Conga 8090 Ultra — 14.4V Li-ion Replacement Battery (84815)

This 14.4V, 6700mAh Li-ion battery replaces part number 84815 in the Cecotec Conga 8090 Ultra, Conga 8090 Ultra T, Conga 8090 Ultra X, and Conga 9090 Ai robotic vacuum cleaners. It slots into the original battery bay and connects to the same BMS handshake the charger expects. Capacity is 96.48Wh — matched to the original cell specification.

• Conga 8090 and 9090 Ai platform fit: These four models share the same 14.4V battery rail, connector pinout, and BMS communication protocol. A single cell revision covers all of them — no adapter or firmware change needed.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the Conga 8090 Ultra dock. The BMS negotiated correctly with the charger, voltage held stable through the motor start surge, and the protection circuit tripped at expected thresholds under load.
• Dock charging behaviour on the Conga platform: Do not leave the robot sitting on the dock permanently between cleans. The Conga charges via continuous contact — no active trickle management cuts the current once full. Remove the unit from the dock when the charge cycle completes to avoid accelerated capacity fade.

Suction dropping before the battery indicator reaches low

This happens when the motor draws more current than the BMS expects — usually because the filter is partially blocked. A restricted airflow path forces the motor to work harder, spiking current draw and pulling voltage below the threshold where the robot maintains full suction power. The BMS reads this as a low-battery condition even when charge is still available. Clean the filter before fitting the new battery — a blocked filter will replicate the same symptom on a fresh cell.

Motor cuts out mid-clean then recovers after a few seconds

This is a BMS overcurrent trip, not a dead battery. When suction is sustained against a blockage — carpet fibres packed at the brush roll, or a clogged pre-filter — current spikes past the protection limit and the BMS shuts the motor circuit down briefly. The trip resets automatically once current drops, which is why the robot appears to recover on its own. Clear the brush roll and check the filter; if the cut-outs continue after cleaning, measure resting voltage on the battery — it should sit above 16.0V when fully charged.