About this replacement
HyperX Cloud Flight / Cloud Alpha Series — 3.7V Li-Polymer Replacement Battery (PL644050)
This 3.7V, 1500mAh Li-Polymer cell replaces the original PL644050 battery in the HyperX Cloud Flight, Cloud Flight S, Cloud Flight Wireless, and Cloud Alpha wireless headsets. It restores full wireless audio operation when the original cell has degraded and no longer holds charge. Voltage and capacity match the OEM spec exactly — 3.7V, 5.55Wh.
- Cloud Flight and Cloud Alpha compatibility: These models share the same battery bay dimensions and connector pinout. The PL644050 cell fits each variant without modification. The BMS in each headset reads cell voltage on insertion and will reject a pack that sits below the wake threshold — a fully charged cell clears this every time.
- Bench tested on actual hardware: We ran this cell in a Cloud Flight unit and monitored BMS handshake on initial insertion. The protection circuit logged the new pack within seconds, charge acceptance began immediately, and the headset reported normal charge status through the LED indicator.
- First-cycle charge protocol for Cloud Flight: Place the headset in the charging cradle and leave it for a complete uninterrupted charge cycle before first use. The Cloud Flight's onboard fuel gauge calibrates against the new cell during this cycle — skipping it causes the battery indicator to misread remaining capacity for the first several sessions.
Why the Cloud Flight cuts out mid-session on a new battery
The Cloud Flight draws from two loads simultaneously — the 2.4GHz wireless radio and the audio DSP. Under combined load, a cell at storage voltage (around 3.6V) can sag below the BMS cutoff threshold briefly, triggering a shutdown. This is not a faulty cell. Charge the battery fully before the first use and the resting voltage will be high enough that sag under combined draw stays above the cutoff point. After two or three full cycles the cell's internal resistance settles and mid-session dropouts stop.
Headset shows full charge on the base but shuts off after a short time
A new cell shipped at storage voltage (typically 3.6–3.7V) can fool the Cloud Flight's LED indicator into displaying a full charge state before the fuel gauge has calibrated. The headset then cuts off sooner than expected because the gauge has no accurate baseline for the new cell's capacity curve. Run one complete charge-to-discharge-to-charge cycle without interruption to let the BMS map the cell. After that cycle the indicator will track remaining capacity accurately. If the problem persists after three cycles, check that the cradle contacts are clean and seating flush — poor contact interrupts the charge current and leaves the cell partially filled.