Logitech UE Boombox 533-000108 Replacement Battery 3.7V 1100mAh

Logitech UE Mini Boombox — 3.7V Li-Polymer Replacement Battery (533-000108)

This 3.7V, 1100mAh Li-Polymer battery replaces the original cell in the Logitech UE Mobile Boombox and Mini Boombox series, including models 880-000248, 886-000015, and S-000136. It fits the slim internal bay and connects to the same BMS circuit the original cell uses. Capacity comes from the product specification at 4.07Wh.

• Mobile Boombox and Mini Boombox series fit: These models share the same 3.7V single-cell architecture, connector pinout, and BMS handshake, so one replacement cell covers the full platform.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a UE Mobile Boombox unit. The BMS accepted the cell without fault codes, balanced normally at full charge, and held the protection thresholds at both ends of the voltage window.
• Monthly discharge cycle for Boombox users: Because this speaker often sits on a desk charging between short sessions, the fuel gauge drifts when the cell never fully discharges. Let the speaker play down past 20% at least once a month before reconnecting the charger — this recalibrates the gauge and slows capacity fade on the Li-Polymer cell.

Audio cutting out at high volume on a freshly charged Boombox

At high volume, the amplifier pulls a sharp current spike on top of the Bluetooth radio draw. If the cell has any internal resistance — from age or a prior deep discharge — the combined load drags the cell voltage below the BMS low-voltage threshold momentarily. The BMS trips the output to protect the cell, and audio cuts. A new cell with lower internal resistance handles the combined amp-plus-radio draw without the sag that trips protection. If it still cuts at high volume after fitting the new cell, check that the connector is fully seated — a loose pin adds contact resistance that mimics a degraded cell under load.

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

Li-Polymer cells self-discharge slowly in storage. If the Boombox sits unpowered long enough, the cell drops below the minimum voltage the USB charging circuit will accept — typically under 2.5V. At that point the charger sees no handshake and does nothing. Apply a constant 5V USB source and leave it connected for at least 20–30 minutes without interruption; the protection circuit needs a sustained trickle to pull the cell back above the acceptance threshold before normal charging can begin. If the indicator still shows no activity after 45 minutes, the cell has over-discharged past recovery and needs replacement.