Microsoft TLL-00002 Replacement Battery 3.8V 1000mAh Li-Polymer

Microsoft TLL-00002 — 3.8V Li-Polymer Replacement Battery (MCOWX11)

This 3.8V, 1000mAh Li-Polymer cell replaces the original battery in the Microsoft TLL-00002 wireless headset. It restores power to the headset's DECT radio and audio circuits when the original cell no longer holds a usable charge. Dimensions are 43.60 × 27.50 × 5.70mm — confirm these against your existing cell before installing.

• TLL-00002 fit: This pack matches the voltage rail, connector, and BMS handshake required by the TLL-00002. The DECT radio and audio amplifier draw simultaneously, so the cell must satisfy both loads without tripping the protection circuit — this one does.
• Bench tested on actual hardware: We cycled the pack through combined DECT transmission and audio load. The BMS held steady across the draw spike at connection, and the protection circuit did not trip under sustained dual-load conditions.
• First charge in the base station: Place the headset in its base station and run a complete charge cycle before taking any calls. The TLL-00002 base station logs the new cell during that first cycle — until it does, the talk-time indicator will read inaccurately.

Base station not recognising the new pack after installation

The TLL-00002 base station communicates with the battery's BMS before registering a charge state. If the new cell arrives at storage voltage — typically around 3.6V — the base may show no charge activity or a blinking error light. This is not a fault with the cell. Seat the headset firmly in the cradle and leave it undisturbed for at least one full charge cycle. After that cycle completes, the base station handshake resets and the charge indicator should read normally.

Talk time shorter than rated on the first few uses

Li-Polymer cells don't deliver full rated capacity straight out of the packaging. On the first two or three cycles, the electrochemical layers haven't fully activated, so available capacity runs noticeably short. This is expected behaviour, not a defective cell. Run three to five full charge-and-discharge cycles through normal headset use and rated capacity will stabilise — no special conditioning steps are needed beyond regular use.