Dyson V8 Replacement Battery 21.6V 4000mAh 215681

Dyson V8 Range — 21.6V Li-ion Replacement Battery (215681)

This 21.6V 4000mAh lithium-ion battery replaces the original pack in Dyson V8, V8 Animal, and V8 Absolute cordless stick vacuums. It matches the OEM voltage rail and BMS handshake required by the V8 platform. Capacity data is sourced from product specifications, rated at 86.4Wh.

• V8 platform compatibility: All V8 variants share the same 21.6V bus, dock connector, and BMS communication protocol. A single cell pack covers the full range without adapter or firmware change.
• Bench tested on actual hardware: We ran this pack on a V8 Absolute through repeated suction cycles. The BMS held stable charge acceptance across multiple charge cycles and showed no false low-battery cutoffs under standard floor and upholstery load.
• Dock charging habit for V8 batteries: Do not leave the V8 sitting on the wall dock continuously between uses. The V8 dock applies a trickle charge when the pack reaches full — over weeks, this compresses cell capacity measurably. Charge to full and remove from the dock.

Suction dropping before the battery indicator reaches low

The V8 motor draws significantly more current when airflow is restricted — blocked filters, full bin, or a partial clog in the cyclone head. Under that elevated load, cell voltage sags early and the BMS reads it as a low-charge condition. The machine reduces power before the indicator LED sequence suggests it should. Clean the filter and empty the bin first — if suction recovers immediately, the battery is not the cause.

Motor cuts out mid-session then restarts after a short pause

This is a BMS overcurrent trip, not a dead battery. When sustained suction restriction forces the motor to pull above the pack's rated discharge ceiling, the BMS disconnects output to protect the cells. It resets after a brief cooldown, which is why the vacuum restarts unprompted. Check the post-motor filter behind the ball joint — if it is grey with dust, airflow restriction is the trigger. Clear the filter and confirm resting pack voltage reads above 21V before assuming cell failure.