Cecotec Conga 8090 Ultra Replacement Battery 14.4V 5200mAh

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

This 14.4V 5200mAh Li-ion battery replaces the original pack in the Cecotec Conga 8090 Ultra, Conga 8090 Ultra T, Conga 8090 Ultra X, and Conga 9090 Ai robotic vacuum cleaners. It matches the OEM voltage rail, connector, and BMS communication protocol. Capacity is 5200mAh (74.88Wh) — drawn directly from the product specification, not estimated.

• Conga 8090 Ultra and 9090 Ai compatibility: These four models share the same 14.4V battery bay geometry, connector pinout, and BMS handshake sequence. The 9090 Ai runs the same power architecture as the 8090 Ultra line, so one cell serves all four without modification.
• Bench tested on actual hardware: We cycled this battery through charge, standby, and full motor-load draw. The BMS held stable voltage under sustained suction load and tripped correctly at the rated low-voltage cutoff — no false shutdowns, no overcurrent events during ramp-up.
• Dock charging practice for Conga robovacs: Do not leave the Conga on the charging dock permanently. Robotic vacuums kept on continuous dock charge develop capacity fade significantly faster than those charged only when depleted. Charge to full and remove from dock until the next clean cycle.

Suction dropping before the battery indicator reaches low

The Conga 8090 Ultra drives its suction motor from the same cell voltage that powers navigation and sensors. When the battery ages and internal resistance climbs, voltage sags under motor load even though the indicator still reads mid-charge. The motor does not get the voltage it needs, so suction output falls before the low-battery warning fires. A fresh cell with lower internal resistance restores full motor voltage and brings suction back to rated performance across the full clean cycle.

Motor cutting out mid-clean and recovering after a pause

This is a BMS overcurrent trip — not a dead battery. It happens when the filter is partially blocked, forcing the motor to pull more current than the BMS threshold allows. The BMS cuts the cell to protect it, the robot stops, and after a short rest the BMS resets and the unit recovers. Clean or replace the filter first. If cut-outs continue with a clean filter, check that cell voltage at rest reads above 14.0V — below that, the battery is too degraded to sustain load spikes.