Soundcast MLD414 Replacement Battery 3.7V 6800mAh

Soundcast MLD414 / Outcast Melody — 3.7V Li-ion Replacement Battery (2-540-006-01)

This is a 3.7V, 6800mAh (25.16Wh) Li-ion replacement battery for the Soundcast MLD414 and Outcast Melody portable Bluetooth speakers. It matches OEM part number 2-540-006-01 and fits the original battery compartment. Use it when the existing cell no longer holds a full charge or fails to power the speaker through a normal listening session.

• MLD414 and Outcast Melody compatibility: Both models run the same 3.7V single-cell architecture with the same connector footprint and BMS communication protocol. The same part number covers both units — no adapter or wiring change needed.
• Bench tested on actual hardware: We cycled this cell through repeated charge and discharge passes on the MLD414 platform. The BMS accepted the pack cleanly, voltage stepped up normally through the protection circuit, and no overcurrent trips were triggered during high-volume amplifier draw.
• Monthly full-discharge cycle for MLD414 users: If the speaker sits on a desk and gets topped off constantly, discharge it below 20% at least once a month before recharging. Constant shallow cycling without a full discharge causes fuel gauge drift — the indicator reads full while actual capacity keeps shrinking.

Voltage sag on the MLD414 amplifier under loud audio

The MLD414 amplifier draws a short, sharp current spike every time bass hits hard or volume exceeds roughly 70%. On an aging or degraded cell, internal resistance rises enough that this spike drags the terminal voltage below the BMS protection threshold. The speaker cuts audio briefly or shuts down entirely — not because the battery is empty, but because instantaneous voltage collapsed. A fresh cell with lower internal resistance handles these transient spikes without voltage dropping out of the safe window.

Speaker won't charge after being left fully discharged for weeks

Li-ion cells left at near-zero charge for an extended period drop below the minimum voltage USB-C PD chargers will accept — typically under 2.5V per cell. At that point the charger detects no valid load and refuses to begin the charge cycle, so the speaker appears completely dead. Most chargers include a trickle pre-charge mode, but the MLD414 circuit may not wake it cleanly. Connect the speaker to a 5V USB-A source rather than a USB-C PD charger first; the lower-voltage source is more likely to trigger the pre-charge stage and bring the cell back above 3.0V.