22.2V Dyson DC31 Replacement Battery 4000mAh Li-ion

Dyson DC31 / DC35 / DC44 Series — 22.2V Li-ion Replacement Battery (17083-2811)

This is a 22.2V, 4000mAh Li-ion replacement battery for Dyson DC31, DC34, DC35, and DC44 cordless handheld vacuums. It replaces a failed or degraded original cell pack and restores the vacuum's ability to run at full motor voltage. Cross-references include OEM part numbers 17083-2811, 18172-01-04, 917083-03, and 917083-05, among others listed above.

• DC31 / DC34 / DC35 / DC44 platform fit: These models share a common 22.2V battery rail, connector footprint, and BMS handshake protocol. A battery built for one will seat and communicate correctly on the others without modification.
• Bench tested on actual hardware: We ran this cell pack through charge and discharge cycles on a DC35 and a DC44 unit. The BMS negotiated correctly with both chargers, cell balancing activated across all six cells, and protection circuits tripped at the expected overcurrent threshold during a simulated blocked-filter draw event.
• Dock charging habit on Dyson handhelds: Do not leave the vacuum sitting on the charging dock permanently. Continuous trickle charge on Li-ion cells accelerates capacity fade faster than normal cycle wear. Charge to full, then remove the unit from the dock.

Suction dropping before the battery indicator reaches low

This happens because a partially blocked filter forces the motor to draw more current than rated to maintain airflow. The BMS reads an overcurrent condition and throttles output voltage to protect the cells — suction drops even though the battery still shows charge. The indicator tracks cell voltage, not motor load, so the gauge looks fine while performance falls away. Clear the filter first; if suction recovers immediately, the battery is not the cause.

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

This is a BMS overcurrent trip, not a dead battery. When airflow is restricted — blocked nozzle, clogged cyclone, or saturated filter — motor current spikes above the BMS trip threshold and the circuit opens to protect the cells. The BMS resets after a short thermal pause, which is why the vacuum restarts on its own. Check the filter and clear any blockage; if the motor still trips on an unobstructed run, measure resting cell voltage — a healthy pack at full charge should read 25.0V to 25.2V across the terminals.