O2 XDA Star Replacement Battery 3.7V 1200mAh Li-Polymer

O2 XDA Star — 3.7V Li-Polymer Replacement Battery (NIKI160)

This is a 3.7V, 1200mAh Li-Polymer cell for the O2 XDA Star Windows Mobile smartphone. It replaces OEM part numbers NIKI160, 35H00103-00M, and 35H00103-01M. The XDA Star uses a slim pouch-style cell measuring 44.36 × 46.50 × 6.38mm — fitment depends on matching all three dimensions, not just voltage.

• XDA Star compatibility: The XDA Star platform uses a dedicated battery bay sized for this exact cell footprint. The BMS connector pinout carries voltage, ground, and a thermistor line — all three are present on this replacement cell, so the handshake with the Windows Mobile charge IC completes correctly.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the XDA Star platform. The BMS engaged cutoff cleanly at the low-voltage threshold, and the charge IC accepted the cell without fault flags on the first cycle.
• Fuel gauge recalibration on first use: After fitting this cell, run one full discharge to automatic shutdown followed by an uninterrupted charge to 100% before normal use. The XDA Star's fuel gauge IC was calibrated to the original cell's discharge curve — one complete cycle resets the coulomb counter against the new cell's actual capacity.

Why the XDA Star reports wrong battery percentage after a cell swap

The XDA Star uses a fuel gauge IC that tracks charge by counting coulombs against a stored discharge curve from the original cell. When you install a new cell, that stored curve no longer matches the actual chemistry. The IC will read percentage from the wrong baseline, so the displayed figure can be off by 15–25%. One full discharge-to-shutdown followed by a full uninterrupted charge forces the IC to re-anchor its end points and recalculate the curve against the new cell.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC has not yet recalibrated and the cell voltage drops below the BMS protection threshold under load — typically during a call or screen-on burst — before the displayed percentage reaches zero. The cell voltage at shutdown is usually around 3.2–3.3V, which is the BMS cutoff floor. Complete the recalibration cycle first: discharge fully until the phone shuts itself off, then charge to 100% without interruption. After that cycle, the percentage readout and the actual cell voltage will track together correctly.