Xiaomi B305GL Cordless Vacuum Replacement Battery 21.6V 4000mAh

Xiaomi Mi G1 Vacuum B305GL — 21.6V Li-ion Replacement Battery (MJGWXDJ)

This is a 21.6V 4000mAh (86.4Wh) lithium-ion battery for the Xiaomi Mi G1 cordless stick vacuum. It fits the B305GL, MJGWXDJ, and Truclean W10 models. The battery slots into the handle housing and powers the brushless motor and suction assembly directly.

• B305GL / MJGWXDJ / Truclean W10 fit: These models share the same 21.6V motor rail, connector pinout, and BMS communication protocol — one battery covers the full group without adaptation.
• Bench tested on actual hardware: We cycled this cell through sustained high-suction draws and confirmed the BMS holds voltage under motor load without nuisance trips. Charge acceptance and cutoff voltages matched OEM specification across multiple charge cycles.
• Dock charging habit on the Mi G1: Do not leave the vacuum sitting on the charging dock continuously. The Mi G1 dock does not interrupt trickle current once full, and cells left on permanent dock charge lose usable capacity faster than cells charged only when depleted. Charge to full, then remove from the dock.

Suction dropping before the battery indicator reaches low

This is a voltage sag issue, not a capacity issue. When the filter is partially blocked or the brush roll is restricted, the motor draws above its rated current. That pulls cell voltage down under load, even when resting voltage still reads healthy. The BMS interprets the sag as a depleted pack and throttles output. Clean the filter and check the brush roll for hair wrap — motor draw should return to normal and the voltage sag will stop triggering early shutdowns.

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

This is a BMS overcurrent trip, not a failed battery. It happens when sustained restricted airflow — blocked filter, tangled brush, or sealed floor head — forces the motor to pull current above the BMS protection threshold. The BMS cuts the circuit to protect the cells, then resets automatically once current demand drops. Clear the restriction first. If the cutout continues after the filter is clean, check that the floor head seal is not creating a full vacuum lock against a hard surface, which spikes draw in the same way.