Haier T20 Cordless Vacuum Replacement Battery 25.2V 4500mAh

Haier T20 — 25.2V Li-ion Replacement Battery

This is a 25.2V Li-ion battery pack rated at 4500mAh (113.4Wh), built to replace the original power cell in the Haier T20 cordless stick vacuum. It fits the T20 platform directly and restores full suction power to the motor. Voltage and capacity match the stock specification from the factory.

• T20 motor rail compatibility: The T20 runs a brushless motor that draws current in short high-demand bursts — especially on carpet or upholstery. This cell's BMS handles those draw spikes without tripping into protection mode during normal use.
• Bench tested on actual hardware: We cycled this battery through load tests matching the T20's motor draw profile. The BMS held stable across restricted-airflow conditions that simulate a partially blocked filter, which is where original cells most often fail early.
• Dock charging behaviour on the T20: Remove the vacuum from the charging dock as soon as the indicator shows full. The T20's dock applies a continuous trickle charge when left connected, and Li-ion cells in this voltage range degrade noticeably faster under prolonged float charging than cells charged only to full and then disconnected.

Suction dropping before the battery indicator reaches low

This is a voltage sag issue, not a capacity issue. When the motor pulls hard against resistance — a blocked filter, thick carpet, or a tight crevice attachment — the cell voltage dips under load even if the resting charge reads normal. The T20's motor controller interprets that sag as a low-battery condition and reduces power to the motor. A degraded original cell sags earlier and harder; a fresh cell at full charge holds the voltage rail steady through those same draw events.

Motor cuts out completely then recovers after a few seconds

This is a BMS overcurrent trip. It happens when sustained restricted airflow — usually a clogged filter — forces the motor to draw more current than the battery protection circuit allows. The BMS cuts power, the motor stops, and after a few seconds the circuit resets and power returns. Replacing the battery without clearing the filter restriction will trigger the same trip repeatedly. Clean or replace the T20 filter first, then confirm the issue is resolved before assuming the cell is at fault.