Logitech 533-000107 Portable Speaker Compatible Battery 3.7V 700mAh

Logitech Far East / S-00149 / S100 — 3.7V Li-Polymer Replacement Battery (533-000107)

This 3.7V, 700mAh Li-Polymer cell replaces the OEM battery in the Logitech Far East, S-00149, and S100 portable wireless speakers. It matches the original pack's footprint at 52.60 × 33.60 × 4.00mm and connects via the factory harness. Capacity figure is 700mAh (2.59Wh) as specified in the product data.

• Far East / S-00149 / S100 platform fit: These three Logitech speaker models share the same internal battery bay dimensions, connector pinout, and 3.7V nominal voltage rail. The BMS in each unit is tuned to the same charge termination voltage, so a single cell revision covers all three without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the S100 platform. The onboard BMS accepted the cell, terminated charge correctly at 4.2V, and the speaker's charge indicator responded as expected with no fault codes thrown.
• Fuel gauge reset after swap: After fitting this cell, run the speaker until the low-battery indicator activates — then charge it fully without interruption. Skipping this step leaves the fuel gauge calibrated to the old, degraded cell, causing the battery indicator to read inaccurately from the first use.

Capacity fade from constant desk-top charging on the S100

The S100 and related models are commonly left plugged in on a desk, topping off continuously at 4.2V. Holding a Li-Polymer cell at full charge under ambient heat from the amplifier accelerates electrolyte oxidation and causes measurable capacity loss within months. The BMS cannot prevent this — it only controls charge termination, not prolonged float storage. If the speaker stays on a desk, unplug it once the charge indicator reads full rather than leaving it tethered overnight.

Audio distorting before the battery indicator reaches empty

This happens when a degraded cell's internal resistance has risen enough that the amplifier's current draw pulls the cell voltage below the audio circuit's stable operating threshold — even though the fuel gauge still shows charge remaining. The amplifier clips under the sag rather than cutting out cleanly, producing distortion. A fresh 700mAh cell restores headroom so the voltage rail holds steady under load. If distortion returns on a new cell within weeks, check that the speaker is not sitting in an enclosed space — amplifier heat accelerates the same internal resistance rise.