HP FA303A#AC3 Bluetooth Headphones Compatible Battery 3.7V 500mAh

HP Bluetooth Stereo Headphones — 3.7V Li-Polymer Replacement Battery (FA303A#AC3)

This 3.7V 500mAh Li-Polymer cell replaces the original battery in the HP Bluetooth Stereo Headphones (FA303A#AC3). It restores wireless audio and call functionality when the original cell has degraded through repeated charge cycles. Capacity is sourced directly from product specifications at 500mAh (1.85Wh).

• FA303A#AC3 and 365830-001 compatibility: Both OEM part numbers reference the same physical cell format — 42.13 x 30.00 x 4.20mm footprint, 3.7V nominal, with the same connector orientation and BMS communication requirements. Swapping either number lands you on the same replacement cell.
• Bench tested on actual hardware: We cycled this cell through the HP headset's charging circuit and confirmed BMS handshake completion, stable cutoff at 4.2V charge termination, and correct low-voltage protection trip below 3.0V under combined audio and Bluetooth radio draw.
• First charge in the base station: Seat the headset in the HP base station and run a complete charge cycle before taking a call. The base station needs that full cycle to log the new cell's state-of-charge curve — skipping it causes the talk-time indicator to read inaccurately for the first several uses.

Why the HP headset cuts out mid-call after a battery swap

The HP Bluetooth Stereo Headphones draw simultaneously from the audio amplifier and the Bluetooth radio during a call. A fresh Li-Polymer cell at partial state-of-charge can't sustain both loads without a brief voltage sag. If that sag dips below the BMS undervoltage threshold — typically around 3.0V under peak draw — the protection circuit trips and cuts power. Running two or three full charge-discharge cycles conditions the cell and stabilises its internal resistance, which reduces sag under combined load.

Base station shows full charge but headset shuts off after a few minutes

A replacement cell shipped at storage voltage (around 3.7V) can fool the base station's charge controller into reading a full charge prematurely. The base sees voltage in the normal range, stops charging, and reports 100% — but the cell hasn't completed a proper formation cycle. Place the headset in the base, leave it for a full uninterrupted charge, and confirm the charging LED completes its full sequence before removing the headset. After that first complete cycle, the base station accurately tracks state-of-charge.