Dyson DC61 21.6V Replacement Battery 965874-02 4000mAh

Dyson DC61 / DC62 / DC58 Series — 21.6V Li-ion 4000mAh Replacement Battery (965874-02)

This is a 21.6V, 4000mAh lithium-ion replacement battery for the Dyson DC58, DC61, and DC62 cordless stick vacuum range. It fits the standard battery bay on all listed models and matches the original cell count and voltage rail. Capacity is rated at 86.4Wh, consistent with the OEM specification.

• DC58 / DC61 / DC62 platform compatibility: These models share the same 21.6V six-cell battery architecture, connector pinout, and BMS handshake protocol. A battery that seats and communicates correctly on the DC61 will do the same on the DC62 Animal and DC58 without modification.
• Bench tested on actual hardware: We ran this battery through charge and discharge cycles on a DC62 unit. The BMS accepted the charger handshake on first connection, reported cell state correctly to the vacuum's indicator LEDs, and held rated voltage under sustained motor load without tripping overcurrent protection.
• Dock charging habit on cordless vacuums: Do not leave the vacuum sitting on the charging dock permanently. Continuous trickle charging accelerates capacity fade in Li-ion cells at this voltage class. Charge to full, then remove the battery or vacuum from the dock until the next use.

Suction dropping before the battery indicator reaches low

The DC61 and DC62 motors draw current in proportion to airflow restriction — a partially blocked filter forces the motor to pull significantly more amps than it would on a clear airflow path. This elevated draw causes voltage to sag at the battery terminals before the indicator LEDs register a low charge state. The vacuum reads the sag as a power issue, but the actual cause is the filter restricting airflow and pushing the motor into a high-draw condition. Wash the cyclone filter, let it dry fully for at least 24 hours, then retest — motor draw should return to the rated operating range.

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 or a heavily restricted filter, current draw spikes past the BMS protection threshold and the battery disconnects the output to protect the cells. After a few seconds the BMS resets and power returns. Clearing the blockage or filter restriction removes the current spike and stops the trip from recurring. If the cutout continues on a clear machine, check that the battery terminal voltage reads at or above 21.0V under load — anything below that on a freshly charged pack indicates cell degradation.