Logitech UE ROLL 533-000122 Replacement Battery 3.7V 3400mAh

Logitech UE Roll / WS600 Series — 3.7V Li-ion Replacement Battery (533-000122)

This is a 3.7V, 3400mAh Li-ion cell replacing OEM part 533-000122 in the Logitech UE Roll and WS600 series portable Bluetooth speakers. It fits the WS600, WS600BL, and WS600VI alongside the UE Roll. Voltage and capacity match the original spec exactly.

• UE Roll and WS600 platform compatibility: All models in this group share the same battery bay dimensions, 3.7V rail, and connector pinout. The BMS handshake is identical across WS600 variants, so one cell services the full line without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a UE Roll unit and monitored the BMS at each stage. The protection circuit responded correctly to both full-charge cutoff and low-voltage disconnect — no spurious trips under normal audio load.
• Fuel gauge recalibration after install: After fitting a new cell, run the UE Roll down to below 20% at least once before topping it off. The speaker's onboard fuel gauge calibrates its empty-to-full range against actual cell behaviour. Skipping this step causes the indicator to read full while the speaker cuts out unexpectedly.

Capacity fade from constant top-off charging on the UE Roll

The UE Roll is typically left on a charging dock or USB cable between uses, which keeps the cell sitting at or near 4.2V for extended periods. Li-ion cells held at peak voltage degrade faster than cells allowed to cycle through a meaningful discharge. Over several months this pattern compresses the usable capacity well below the rated 3400mAh. Letting the cell drop below 20% once a month before recharging slows that degradation noticeably.

Audio distorting before the battery indicator reaches empty

This symptom appears when the cell's internal resistance has risen enough to cause voltage sag under amplifier load, even though the resting voltage still reads mid-range. The amplifier draws a spike of current at higher volumes, and the sagging cell voltage pulls the amp's supply rail below its clean-operation threshold — producing clipping before the low-battery warning fires. A worn cell will show this pattern consistently; a new cell at 3400mAh holds the voltage rail stable through the same current draw. If distortion clears up at lower volume but returns above 70%, the cell is the cause.