LG XG5QBK Bluetooth Speaker Replacement Battery 3.8V 3900mAh

LG XG5QBK / XBOOM Go DXG5Q — 3.8V Li-Polymer Replacement Battery (EAC63558705)

This 3.8V, 3900mAh Li-Polymer battery replaces the original pack in the LG XG5QBK and XBOOM Go DXG5Q portable Bluetooth speakers. It fits both OEM part numbers EAC63558705 and EAC64790804. Install it when the speaker no longer holds charge, powers off unexpectedly, or won't leave the charger.

• XG5QBK and XBOOM Go DXG5Q compatibility: Both models share the same 3.8V battery bay, connector pinout, and BMS handshake protocol — one cell covers both. The fuel gauge IC on the speaker's main board reads cell state-of-charge directly, so the replacement pack communicates the same way as the original.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the speaker platform. The BMS accepted full charge without flagging a fault, and audio output held steady across the draw range from low-volume ambient playback to sustained high-volume output.
• Monthly discharge cycle for XG5QBK users: If you top this speaker off every night before it drops below 50%, the fuel gauge drifts over weeks and reported capacity shrinks faster than the cell actually degrades. Let the speaker discharge below 20% at least once a month before plugging in — it recalibrates the gauge and slows capacity fade on the Li-Polymer cell.

Audio distorting before the battery indicator reaches empty

As a Li-Polymer cell discharges, internal resistance rises. On the XG5QBK, the amplifier draws a surge of current during loud playback — that surge across rising internal resistance causes a voltage dip at the cell terminals. The amplifier clips under that sag before the battery LED has reported empty. This is not a faulty battery; it is the amplifier hitting its minimum operating voltage while the fuel gauge still shows reserve. If distortion starts during high-volume use, drop the volume by 20–30% — the current draw falls, the sag shrinks, and playback clears up. A worn cell accelerates this behaviour; a fresh 3900mAh pack restores the voltage headroom the amplifier needs.

Speaker won't respond to USB-C after sitting unused for weeks

Li-Polymer cells self-discharge in storage. If the XG5QBK sat long enough for the cell to drop below roughly 2.5V per cell, the USB-C PD controller on the speaker rejects incoming charge because the cell voltage is below its minimum acceptance threshold. The speaker appears completely dead — no LED, no response. Connect it to a 5V USB-A charger rather than a USB-C PD source; the lower-current trickle path on 5V is more likely to coax the BMS into recovery mode. Hold the connection for at least 30 minutes before attempting a USB-C PD charge.