About this replacement
Soundcast MLD414 / Outcast Melody — 3.7V Li-ion Replacement Battery (2-540-006-01)
This is a 3.7V 5200mAh Li-ion replacement battery for the Soundcast MLD414 and Outcast Melody portable Bluetooth speakers. It matches OEM part number 2-540-006-01 and restores power to units where the original cell has degraded. Capacity figure comes from the product data: 5200mAh / 19.24Wh.
- MLD414 and Outcast Melody compatibility: Both models run the same 3.7V single-cell platform with the same physical footprint (65.96 × 36.80 × 18.90mm) and share the 2-540-006-01 part number. The BMS handshake and connector are identical across both units — one cell covers both.
- Bench tested on actual hardware: We cycled this cell through repeated charge and discharge loads that mirror the combined amplifier and Bluetooth radio draw. The BMS held stable cutoff thresholds at both low-SoC and high-draw peaks without spurious shutdowns.
- Monthly full-discharge cycle for the MLD414: Soundcast speakers are frequently left on a desk and topped off constantly. Let the cell drain below 20% at least once a month before recharging. Constant partial-charge cycling without a full discharge causes fuel gauge drift on the MLD414's charge indicator, making it read full when the cell is already degraded.
Why the MLD414 shows full charge but audio cuts out after extended play
A degraded cell loses usable capacity faster than the charge indicator tracks. The fuel gauge on the MLD414 reads state-of-charge based on voltage curves calibrated to a healthy cell. When the cell ages, its internal resistance rises — voltage sags quickly under amplifier load even when the indicator still shows significant charge remaining. The BMS hits its low-voltage cutoff and shuts the unit down before the indicator reaches empty. Replacing the cell resets that gap between displayed and actual charge.
Audio distorting before the battery indicator reaches empty
This is amplifier clipping caused by voltage sag, not a speaker fault. At high volume, the combined current draw from the amplifier and Bluetooth radio pulls the cell voltage down sharply. When cell voltage drops below roughly 3.4V under load, the amplifier rail can't sustain clean output and the signal clips. The distortion disappears at lower volume because the current draw drops and the sag reduces. If distortion starts earlier in each charge cycle, the cell's capacity has faded — replace it and confirm clean playback at full volume with the indicator above 50%.