Shark IW4624 Replacement Battery 18V 3750mAh XBTR540

Shark IW4624 / IW4625 — 18V Li-ion Replacement Battery (XBTR540)

This 18V 3750mAh (67.5Wh) Li-ion battery replaces the original XBTR540, XBTR540DC, and XBTR540DCEU cells in the Shark IW4624 and IW4625 cordless stick vacuums. It powers the motorized brush roll and suction motor through the same BMS handshake the charger expects. Capacity figures are taken from the product data, not estimated from third-party sources.

• IW4624 and IW4625 platform fit: Both models run the same 18V power rail and share an identical battery bay connector and BMS communication protocol — one cell covers both units without modification.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the IW4624 chassis. The BMS accepted the charger handshake immediately, and overcurrent protection triggered correctly under a simulated blocked-filter load before resetting cleanly.
• Dock charging habit on the IW4624: Do not leave this vacuum sitting on the charging dock permanently. Continuous trickle charge accelerates capacity fade in Li-ion stick vacuum batteries faster than nearly any other use pattern. Charge to full, then remove from the dock.

Cordless vacuum losing suction before the battery indicator reaches low

This is almost never a dead battery — it is usually motor voltage sag caused by a partially blocked filter forcing the motor to draw above its rated current. When airflow is restricted, the motor works harder, pulls more amps, and the BMS sees a sustained overcurrent condition before the cell is anywhere near depleted. The voltage at the motor terminals drops, suction weakens, and the battery indicator still reads mid-range because the cell itself has charge remaining. Clean or replace the foam and HEPA filters first, then retest suction before concluding the battery is the fault.

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

This is a BMS overcurrent trip, not a battery failure. On the IW4624, sustained restricted airflow — from a full dustbin, matted brush roll, or clogged post-motor filter — drives amp draw high enough that the BMS trips the output to protect the cell. The battery goes quiet, recovers in a few seconds, then powers back on. The fix is mechanical, not electrical: clear the blockage, empty the bin, and check that the brush roll spins freely. If the trip still occurs after clearing all restrictions, measure resting cell voltage — a healthy 18V Li-ion cell should read between 20.0V and 21.6V fully charged.