Sony WH-1000XM3 Replacement Battery 3.7V 1000mAh SP624038

Sony WH-1000xM3 / WH-XB900N Series — 3.7V Li-Polymer Replacement Battery (SP 624038)

This is a 3.7V, 1000mAh Li-Polymer battery for the Sony WH-1000xM3 wireless headphones and compatible models in the WH series. It restores power to headphones where the original cell has degraded, stopped holding charge, or failed entirely. Fits WH-1000xM3, WH-CH710N/B, WH-XB900, and WH-XB900N using OEM part numbers SP 624038, SM-03, 1588-0911, and LIS1662HNPC.

• WH-series compatibility: These models share the same 3.7V single-cell Li-Polymer architecture, connector pinout, and BMS handshake protocol. Sony consolidated the power design across this headphone range, so the same cell works across all four models without modification.
• Bench tested on actual hardware: We cycled this battery in a WH-1000xM3 unit and confirmed the BMS completed its handshake on first charge. The protection circuit responded correctly to both over-charge and over-discharge cutoff thresholds during testing.
• First-cycle charge protocol for WH headphones: Place the headphones on the USB-C charge cable for a full, uninterrupted charge before use. The WH-1000xM3 firmware reads cell state during the first charge cycle to calibrate the battery indicator — skipping this causes the charge display to read inaccurately for the first week of use.

Why the WH-1000xM3 cuts out mid-call on a new battery

The WH-1000xM3 runs three simultaneous loads during a call: Bluetooth radio, active noise cancellation DSP, and microphone processing. On a freshly installed cell that hasn't completed its first full cycle, the resting voltage sits around 3.6–3.7V and sags under combined draw. The BMS interprets this sag as a low-cell condition and triggers a protective cutoff before the cell is actually depleted. Running two or three full charge-discharge cycles brings the cell to rated capacity and eliminates the sag that causes the dropout.

Battery indicator stuck at full — then headphones cut off without warning

This happens when the replacement cell arrives at storage voltage (typically 3.6–3.7V) and the firmware reads that as a near-full state without a calibration cycle. The indicator shows full because no discharge reference point exists yet. The headphones then shut off abruptly once the cell hits the BMS low-voltage cutoff, with no warning from the indicator. Fix this by running one complete charge from flat to full via USB-C, which lets the firmware establish accurate low and high voltage reference points for the indicator.