Haier A500 Replacement Battery 21.9V HJ-6101 4000mAh

Haier A500 Series — 21.9V Li-ion Replacement Battery (HJ-6101)

This is a 21.9V, 4000mAh (87.6Wh) Li-ion replacement battery for the Haier A500 cordless vacuum and the A500 Floor Washing Machine 3-in-1 Automatic Mopping & Drying unit. It uses OEM part number HJ-6101 and fits the same battery bay with the same connector and BMS communication as the original. When the factory cell degrades and suction weakens before the indicator hits low, this swap restores full motor voltage.

• A500 and A500 Floor Washing compatibility: Both variants share the same 21.9V battery bay, connector pinout, and BMS handshake protocol. Swapping between vacuum-only and mopping modes puts different current demands on the pack, but the HJ-6101 cell spec covers both draw profiles without triggering a protection trip under normal use.
• Bench tested on actual hardware: We ran this pack through motor-start inrush cycles on the A500 platform and confirmed the BMS holds without dropping into overcurrent protection. Cell voltage under sustained load stayed within the motor controller's operating window across multiple cleaning passes.
• Dock charging on the A500: Do not leave the A500 sitting on the charging dock permanently. Continuous trickle charging after full capacity is reached accelerates capacity fade in Li-ion cells. Charge to full, then remove the vacuum from the dock until the next use.

Suction dropping before the battery indicator reaches low on the A500

This happens when the filter is partially blocked — the motor works harder against the restriction and draws more current than rated, pulling cell voltage down faster than the indicator tracks. The indicator measures state of charge, not motor load, so it can still show two bars while suction has already fallen. Check and clean the filter first. If suction recovers after a clean filter, the battery is not the cause. If suction is still weak after a filter clean, measure pack voltage under load — a degraded cell will sag below 19V during sustained run.

A500 motor cutting out mid-clean then recovering after a few seconds

A momentary BMS overcurrent trip causes this — not a dead battery. On the A500, sustained suction against a blocked nozzle or clogged filter forces the motor to spike current beyond the protection threshold, and the BMS shuts the output to protect the cells. It resets automatically once current demand drops. Clear the nozzle, clean the filter, then restart. If the cutout continues on a clear nozzle and clean filter, the original battery's cells have degraded enough that the BMS trips at normal motor loads — that is when a replacement pack is the fix.