HOBOT Legee D7 Replacement Battery 14.4V 5000mAh

HOBOT Legee D7 / Legee D8 — 14.4V Li-ion Replacement Battery (21700 4S1P-L)

This is a 14.4V, 5000mAh (72Wh) Li-ion replacement battery for the HOBOT Legee D7 and Legee D8 robotic vacuum cleaners. It replaces OEM part number 21700 4S1P-L. When the original pack degrades, the robot loses the sustained power it needs to complete a full cleaning cycle.

• Legee D7 and D8 compatibility: Both models share the same 14.4V architecture, connector type, and BMS handshake protocol, so one pack covers either unit without modification.
• Bench tested on actual hardware: We ran this pack through charge and discharge cycles on the Legee D7 platform. The BMS responded correctly to the robot's charge termination signal and did not trip on motor-start current draw during navigation.
• Dock charging habit on the Legee D7 and D8: Do not leave the robot parked on the charging dock continuously between uses. Constant trickle charging accelerates capacity fade in Li-ion packs. Charge to full, then remove from the dock until the next scheduled clean.

Suction dropping before the battery indicator reaches low

The Legee D7 regulates motor speed based on available voltage from the pack. As a Li-ion cell ages, its internal resistance rises — voltage sags under motor load even when the reported state of charge still reads moderate. The robot interprets this sag as sufficient charge but the motor cannot sustain full suction pressure. A replacement pack with lower internal resistance restores stable voltage under load and brings suction back to spec.

Motor cutting out mid-clean and then recovering

This is a BMS overcurrent trip, not a dead battery. When the Legee D7's filter is partially blocked, the motor works harder to maintain airflow and draws current above the BMS threshold. The BMS cuts power to protect the cells, then resets after a few seconds. Clean or replace the HEPA filter first — if the cutout stops, the battery was never the cause. If it continues with a clean filter, check that pack voltage at rest reads above 12.0V before assuming a cell fault.