About this replacement
Sony NWZ-W202 / SBH80 — 3.7V Li-Polymer Replacement Battery (LP401225)
This is a 3.7V, 80mAh Li-Polymer replacement battery for the Sony NWZ-W202 and SBH80 wireless headsets. It matches OEM part number LP401225 and fits the compact cell bay in both models. At 26.20 x 12.00 x 4.00mm, it slots into the same housing as the original cell.
- NWZ-W202 and SBH80 compatibility: Both models share the same LP401225 cell footprint, voltage rail, and BMS handshake protocol — one replacement covers both. The connector pinout and cell dimensions are identical across the two.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the NWZ-W202 platform. The BMS accepted the new pack without error flags, and charge termination cut in cleanly at full voltage.
- First-charge protocol on DECT and wireless headsets: On first use, seat the headset in its charging cradle and run a complete charge cycle before audio playback. The headset's charge controller needs one full cycle to log the new cell and calibrate its charge-state readout accurately.
Why the NWZ-W202 cuts out mid-playback under combined radio and audio draw
The NWZ-W202 runs Bluetooth radio and audio decoding simultaneously from an 80mAh cell. When both subsystems draw current at the same time — particularly during high-bitrate audio or signal reconnection — instantaneous current demand spikes. A degraded or storage-voltage cell can't sustain that spike, so the BMS trips the output to protect the cell. A fresh, fully charged LP401225 cell holds the voltage rail stable through those combined-load peaks without tripping the cutoff.
Base station shows full charge but headset cuts off after short use
This happens when the replacement cell is at storage voltage — typically around 3.6–3.7V — rather than a true full charge. The charge controller reads that as near-full and terminates early. The fix is straightforward: leave the headset seated in the cradle for a complete uninterrupted charge cycle, confirmed by the charge indicator going from active to complete. After that first full cycle, the controller recalibrates and subsequent charges terminate at the correct 4.2V endpoint.