LG CordZero R9 Replacement Battery 21.6V 5000mAh EAC64578401

LG CordZero R9 / R87 Series — 21.6V Li-ion Replacement Battery (EAC64578401)

This 21.6V, 5000mAh (108Wh) Li-ion battery replaces the original pack in the LG CordZero R9, R9MASTER, R87, and BDV1 cordless vacuum cleaners. It matches the OEM voltage rail and BMS handshake the motor controller expects. Fits models referencing part numbers EAC64578401, EAC64578402, EAC63419401, EAC63419402, and EAC63419404.

• R9 and R87 platform compatibility: The R9 and R87 share the same 21.6V battery bay, connector pinout, and BMS communication protocol. One cell format covers both vacuum lines — no adapter or modification needed.
• Bench tested on actual hardware: We cycled this pack through full charge and discharge on the CordZero platform. The BMS negotiated correctly with the charger, current limiting engaged at the expected threshold, and no false low-battery cutoffs occurred during sustained motor load.
• Dock charging habit for CordZero users: Do not leave the vacuum on the charging dock permanently. CordZero vacuums on continuous dock charge develop capacity fade significantly faster than those charged only when depleted. Charge to full and remove from the dock.

Suction dropping before the battery indicator reaches low

The CordZero motor draws higher current when the filter is partially blocked — the vacuum works harder to pull the same airflow. Under that sustained high draw, a degraded cell pack sags below the motor controller's minimum voltage threshold before the indicator registers low. The vacuum loses power to protect itself, even though the displayed charge looks adequate. A fresh 21.6V pack with full cell capacity holds voltage under that load where a worn pack cannot.

Motor cuts out mid-clean then recovers after a short pause

This is a BMS overcurrent trip, not a fault with the motor itself. When suction is restricted — blocked filter, clogged brush roll, or a sealed floor surface — the motor demands current above the BMS cutoff threshold. The BMS disconnects to protect the cells, the motor stops, and after a brief thermal reset window the vacuum restarts. Check and clean the filter first. If the trip persists on a clear filter with a worn battery, the aged cells are spiking internal resistance high enough that normal motor-start draws trigger the overcurrent threshold — replace the pack and verify the restart occurs cleanly at full charge.