Marshall Emberton 3 Replacement Battery 7.4V 3400mAh

Marshall Emberton 3 — 7.4V Li-ion Replacement Battery (B0797)

This is a 7.4V 3400mAh (25.16Wh) Li-ion replacement battery for the Marshall Emberton 3 portable Bluetooth speaker. It fits the Emberton III under both naming conventions. When the original cell degrades and the speaker stops holding a useful charge, this battery restores full function.

• Emberton 3 / Emberton III compatibility: Both names refer to the same hardware generation. The battery connector, cell voltage, and BMS handshake are identical across both variants — one part number covers both.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the Emberton 3 platform. The BMS accepted the pack without error flags, and the fuel gauge calibrated correctly within the first two cycles.
• Monthly discharge cycle on daily-use speakers: If this speaker sits on a desk and gets topped off constantly before dropping below 50%, discharge it fully below 20% at least once a month before recharging. Constant shallow cycling causes fuel gauge drift and accelerates capacity fade on the Li-ion cell faster than normal use would.

Audio distorting before the battery indicator reaches empty

The Emberton 3 amplifier draws a sharp current spike at high volume. When the cell voltage sags under that combined amplifier and radio load, the amp clips before the battery indicator triggers low-battery cutoff. The speaker sounds distorted — but the indicator still shows charge remaining. This is voltage sag, not a capacity problem. If distortion appears consistently at high volume during the last third of a charge cycle, the cell has degraded below the point where it can sustain peak current draw. A fresh cell at 3400mAh holds voltage under that spike and clears the distortion.

Speaker won't wake from USB-C after sitting unused for weeks

Li-ion cells left discharged for extended periods drop below the USB-C PD minimum acceptance voltage — typically under 2.5V per cell. At that level, the BMS blocks the charge path to protect the cell, and the speaker appears completely dead on any USB-C cable. Connect the speaker to a USB-C charger and leave it undisturbed for 20–30 minutes without expecting an immediate response. The BMS runs a trickle pre-charge sequence to bring the cell back above the acceptance threshold — around 3.0V per cell — before normal charging resumes. If the speaker still shows no sign of life after 45 minutes, the cell has dropped too far to recover and the battery needs replacement.