About this replacement
Harman/Kardon SOHO — 3.7V Li-Polymer Replacement Battery (P462539)
This 3.7V 480mAh Li-Polymer cell replaces part number P462539 in the Harman/Kardon SOHO on-ear Bluetooth headphones. It restores wireless audio playback and call functionality when the original cell has degraded. Dimensions are 40.50 × 25.46 × 5.12mm — confirm against your existing cell before fitting.
- SOHO platform fit: The SOHO headset runs a single-cell 3.7V Li-Polymer pack with a BMS that monitors cell voltage and reports charge state to the paired device. This replacement uses the same connector pinout and BMS handshake parameters as the original P462539.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the SOHO platform and confirmed the BMS completed its handshake, reported charge state accurately, and held stable voltage under combined Bluetooth radio and audio driver draw.
- First-cycle charging protocol: Seat the headset in its charging cradle immediately after fitting and let it complete one full charge cycle before use. The SOHO base station logs the new cell during this cycle — skipping it causes the charge indicator to report inaccurately for the first several uses.
Why the SOHO cuts out mid-call on a new battery
The SOHO headset draws simultaneously from the Bluetooth radio and audio driver during calls. That combined load pulls more current than audio playback alone, which causes a voltage sag on cells that haven't completed their first conditioning cycle. The BMS interprets the sag as a low-cell event and cuts output to protect the cell. Running two to three full charge and discharge cycles brings the cell to rated capacity and eliminates the sag that triggers the cutoff.
Base station shows full charge but headset shuts off after a few minutes
A new Li-Polymer cell ships at storage voltage — typically around 3.6V — not at full charge. The base station's charge indicator can read this as "charged" before the cell has actually been topped up through a proper charge cycle. The headset then shuts off quickly because the cell never reached its rated 3.7V working voltage. Fix: place the headset in the cradle and leave it undisturbed until the charge indicator confirms a complete cycle, then verify the resting cell voltage reads at or above 3.7V before use.