Electrolux Osiris 7.2V Replacement Battery S91-0400410-SU2

AEG Electrolux Osiris — 7.2V Li-ion Replacement Battery (S91-0400410-SU2)

This 7.2V, 3400mAh Li-ion battery replaces the original pack in the Electrolux Osiris cordless stick vacuum. It fits the Osiris range including model numbers 900258195, RX7-1-TM, and 900277268, among others. Voltage and capacity match the OEM spec exactly — no modifications needed.

• Osiris platform compatibility: The Osiris series runs a shared 7.2V battery rail across its variants. All listed models use the same connector layout and BMS handshake, so the pack communicates correctly with the vacuum's motor controller without triggering a fault state.
• Bench tested on actual hardware: We ran this pack through full charge and load cycles on an Osiris unit. The BMS held cutoff thresholds within spec under sustained motor draw and recovered cleanly after a full discharge cycle with no fault flags thrown.
• Dock charging habit on the Osiris: Do not leave the Osiris sitting on the charging dock permanently. Continuous trickle charge from the dock accelerates capacity fade in Li-ion cells faster than normal cycling. Charge to full, then remove it from the dock between uses.

Osiris suction dropping before the battery indicator reaches low

The Osiris motor draws significantly more current when airflow is restricted — a partially blocked filter is the most common cause. Under that extra load, the battery's BMS detects a voltage sag and begins throttling power to the motor before the indicator registers low. The vacuum feels like a weak battery when the actual problem is filter restriction driving up current draw. Clean or replace the filter first, then retest — motor draw should return to under 3A at full suction.

Motor cutting out mid-clean and then recovering after a few seconds

This is a BMS overcurrent trip, not a failed battery. When sustained suction restriction forces the motor to pull more current than the BMS threshold allows, the pack shuts off to protect the cells and resets after a brief cooldown. It will keep happening until the restriction is cleared. Check the filter and the brush-roll channel for blockages — once airflow is restored, the BMS should stop tripping under normal carpet load.