About this replacement
Sony YY7862E / SRS-XB31 / SRS-XB32 / SRS-XB33 — 7.4V Li-ion Replacement Battery (IAJ002NA)
This is a 7.4V 3000mAh Li-ion replacement battery for the Sony YY7862E and SRS-XB31/32/33 portable Bluetooth speakers. It matches the original cell chemistry and connector config. Capacity figures are from the product spec sheet — 3000mAh / 22.2Wh.
- SRS-XB31/32/33 platform compatibility: These three speaker generations share the same battery bay dimensions, connector pinout, and BMS handshake protocol. Swapping between them requires no modification — the voltage rail and cell configuration are identical across the series.
- Bench tested on actual hardware: We ran this pack on the SRS-XB33 under combined Bluetooth radio and amplifier draw at mid-to-high volume. The BMS held steady through repeated amp current spikes without tripping into protection mode. Voltage stayed within spec across the discharge curve.
- Fuel gauge calibration on these speakers: Let the speaker discharge below 20% at least once a month before recharging. Constant top-off charging — plugging in before the battery drops below half — causes fuel gauge drift on the Li-ion cell and accelerates capacity fade over time.
Bluetooth dropping at high volume on the SRS-XB31/32/33
High-volume playback on the XB series pulls current from both the amplifier and the Bluetooth radio simultaneously. On a degraded or deeply discharged cell, this combined draw causes a voltage sag that trips the BMS momentarily — cutting the radio connection before audio resumes. The speaker may appear to reconnect immediately, making the fault look like a wireless issue rather than a power issue. If Bluetooth drops only at high volume and the battery indicator is below 40%, the cell is the cause.
Audio distorting before the battery indicator reaches empty
When the cell voltage sags under amplifier load, the amp clips before the battery indicator shows low. The speaker's fuel gauge reads remaining charge based on resting voltage, not load voltage — so a fatigued cell can show 30% remaining while the amplifier is already starved of headroom. The result is audible distortion, particularly on bass-heavy tracks, well before the low-battery warning triggers. Charge the speaker to 100% and check whether distortion disappears — if it does, the cell is the fault.