Sony SRS-XG300 Replacement Battery 7.4V 6700mAh Li-ion

Sony SRS-XG300 — 7.4V Li-ion Replacement Battery (903867-2S2P)

This 7.4V 6700mAh Li-ion battery replaces the original 903867-2S2P pack in the Sony SRS-XG300 portable Bluetooth speaker. It fits the SRS-XG300 directly and restores wireless operation when the original cell has degraded past usable capacity. Capacity is rated at 49.58Wh, matching the original specification.

• SRS-XG300 fit: The SRS-XG300 uses a 2S2P lithium-ion pack at 7.4V nominal. This replacement matches that voltage rail and cell configuration, so the speaker's onboard BMS communicates with the pack the same way it did with the factory battery.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on the SRS-XG300 platform. The BMS accepted the pack without fault codes, balanced the cells correctly across both charge and audio-load discharge, and held voltage within spec at moderate and high playback volumes.
• Discharge cycling for SRS-XG300 users: This speaker is frequently kept on a desk or charged after short sessions. Let the battery discharge below 20% at least once a month before recharging — constant top-off charging without a full discharge cycle causes fuel gauge drift, which makes the battery indicator unreliable and accelerates capacity fade in the Li-ion cells.

Why the SRS-XG300 shows full charge but audio drops after extended play

This happens when the fuel gauge has drifted from months of shallow cycling — the speaker reports a high state of charge, but the actual cell capacity is lower than the BMS expects. Under amplifier load, the voltage sags faster than the indicator tracks, so the speaker cuts audio protection before the gauge reaches empty. A full discharge down to the BMS cutoff voltage, followed by a complete recharge, resets the gauge calibration. After one or two full cycles, the reported charge level will track actual cell voltage accurately again.

Audio distorting before the battery indicator reaches empty

At high playback volumes, the amplifier in the SRS-XG300 draws a sharp current spike that causes the battery voltage to sag momentarily below the amplifier's clean-power threshold. The amp clips the signal rather than shutting down, which sounds like distortion even though the battery indicator still shows charge remaining. This is a voltage-sag issue, not a speaker fault. Charge the pack fully to 8.4V and test again at the same volume — if distortion disappears at full charge, the cell needs replacement rather than the speaker.