Geek Aire CF2 Replacement Battery 21.6V 3200mAh Li-ion

Geek Aire Fan CF2 — 21.6V Li-ion Replacement Battery (INR18650-6S1P)

This 21.6V Li-ion pack replaces the original battery in the Geek Aire CF2 portable cooling fan. It uses a six-cell series configuration (INR18650-6S1P) and carries a rated capacity of 3200mAh (69.12Wh). When the original cells degrade and the fan loses speed or shuts down early, this pack restores full motor voltage.

• CF2 motor voltage rail: The CF2 fan motor requires a stable 21.6V supply to hit all three speed settings. A six-cell series pack is the only configuration that meets this rail — five cells sag under high-speed load, and the motor controller drops to a lower speed mode to compensate.
• Bench tested on actual hardware: We ran this pack through the full CF2 speed range and monitored BMS cutoff behaviour. The BMS held voltage above 19.8V across low and medium speeds and tripped cleanly at the low-cell threshold on a simulated depleted cell — no false cutoffs on the high-speed draw spike.
• First-cycle conditioning on the CF2: Run the fan at medium speed for the first charge cycle. Maximum speed draws peak current from an uncalibrated cell, which can cause the BMS to set conservative capacity limits that persist until the cells are fully conditioned.

Fan speed dropping before the low-battery indicator lights up

This happens when individual cells in the series string age unevenly. The weakest cell sags under high-speed current draw, pulling the pack voltage below the motor controller's threshold before the battery indicator registers low. The indicator reads average pack voltage, not the weakest cell. A new pack with matched cells eliminates this — all six cells sag together, and the indicator triggers at the correct point.

CF2 not reaching maximum speed on a new battery

If the fan won't hit maximum speed after fitting a replacement pack, the BMS may have latched conservative current limits from the first charge cycle. This occurs when high-speed draw runs before the cells are conditioned. Run two full charge-discharge cycles at medium speed, then attempt maximum speed. If the issue persists, check that the pack voltage reads at least 21.0V at rest before spinning the motor.