About this replacement
Sony SRS-XG300 — 7.4V Li-ion Replacement Battery (903867-2S2P)
This is a 7.4V, 5200mAh (38.48Wh) Li-ion replacement battery for the Sony SRS-XG300 portable Bluetooth speaker. It uses OEM part number 903867-2S2P and slots directly into the speaker's internal battery bay. When the original cell loses capacity after repeated charge cycles, this unit restores full wireless audio playback capability.
- SRS-XG300 fitment: The XG300 runs a dual-cell 2S2P Li-ion configuration at 7.4V nominal. This pack matches that voltage rail, connector pinout, and BMS communication protocol — the speaker's protection circuit recognises the pack and allows full charge and discharge cycles.
- Bench tested on actual hardware: We cycled this pack through the XG300's charge circuit and confirmed the BMS handshake, thermal cutoff response, and cell balancing at both high-volume amplifier draw and Bluetooth idle. No false low-battery flags appeared during the discharge run.
- Discharge cycling for fuel gauge accuracy: If the speaker is kept plugged in or topped off constantly, let the battery discharge below 20% at least once a month before recharging. Without a full discharge cycle, the fuel gauge drifts and the indicator becomes unreliable.
Audio distorting before the battery indicator reaches empty
As the pack discharges toward 6.8V, the amplifier stage in the XG300 begins clipping because it can no longer draw the current needed for high-volume output. This causes audible distortion — crackling or compressed audio — while the battery indicator still shows one or two bars. The BMS has not yet hit its cutoff threshold, but the cell voltage has sagged below the amplifier's stable operating point. If this happens consistently, recalibrate the fuel gauge by running a full discharge to automatic shutoff, then charging uninterrupted to 100%.
Speaker won't wake from USB-C after a deep discharge
If the SRS-XG300 sits unused for several weeks, the cell voltage can drop below the USB-C Power Delivery minimum acceptance threshold — typically under 2.5V per cell. At that point, the speaker will not respond to a USB-C cable at all. Connect the speaker to a USB-C charger rated at 5V/1.5A or higher and leave it connected for at least 20 minutes without pressing any button — the BMS needs time to trickle-charge the cells back above the PD acceptance floor before it will negotiate a full charge session.