About this replacement
Dyson DC31 / DC35 Series — 22.2V Li-ion Replacement Battery (17083-2811)
This is a 22.2V, 2500mAh lithium-ion battery for the Dyson DC31, DC34, DC35, and DC44 cordless handheld vacuums. It replaces OEM part numbers 17083-2811, 17083-4211, 917083-03, 917083-05, and several others in that family. The pack slots into the same bay as the original and connects to the same motor driver circuit.
- DC31 / DC34 / DC35 / DC44 platform fit: These models share a common 22.2V power rail, identical battery bay dimensions, and the same BMS handshake protocol. One cell pack covers the full range because Dyson standardised the connector and communication line across this generation of handheld vacuums.
- Bench tested on actual hardware: We ran this pack through full charge and discharge cycles on a DC35 motor unit. The BMS responded correctly to overcurrent events — tripping and resetting without lockout — and cell balancing completed within expected parameters across repeated cycles.
- Dock charging behaviour on this vacuum: Do not leave the DC31 or DC35 sitting on the wall dock between uses. These vacuums trickle charge continuously when docked, and that sustained low-current feed degrades cell capacity faster than normal discharge cycling. Charge to full, then remove from the dock.
Cordless vacuum losing suction before the battery indicator reaches low
This happens when the motor draws more current than the BMS allows under load — usually caused by a partially blocked filter or a tangled brush bar forcing the motor to work harder. The pack's voltage sags under that elevated draw, and the motor controller reduces power before the fuel gauge registers low. Clean the filter and clear the brush bar first. If suction restores immediately, the battery is not the cause — the restricted airflow was pulling the pack below its sag threshold.
Motor cuts out mid-use then recovers after a short pause
This is a BMS overcurrent trip, not a dead cell. When suction is blocked — by a clogged filter, a sealed nozzle, or heavy carpet fibres — current draw spikes and the BMS shuts the output to protect the cells. Releasing the trigger for 10–15 seconds lets the BMS reset and the pack cools slightly. If it trips again immediately on restart, inspect the filter and airway before assuming the battery has failed. A fully clear airpath should hold the pack above its 18V cutoff under normal carpet load.