Nubia Alpha SW1002 Replacement Battery 3.85V 450mAh

Nubia Alpha SW1002 — 3.85V Li-Polymer Replacement Battery (Li3905T44P6h292752)

This is a 3.85V, 450mAh Li-Polymer cell for the Nubia Alpha SW1002 smartwatch. It replaces the original Li3905T44P6h292752 battery when capacity fade sets in after repeated charge cycles. The Alpha SW1002 is a wrist-worn flexible display watch — this cell powers the display, heart rate sensor, and BLE radio.

• Alpha SW1002 platform fit: The SW1002 uses a compact 27.46 × 26.60 × 5.10mm cell with a specific connector orientation to clear the flexible display assembly. Voltage must match at 3.85V — the PMIC on this platform does not regulate down from a higher-voltage cell.
• Bench tested on actual hardware: We cycled this cell through the SW1002's charge controller and confirmed the BMS accepted the new cell without fault codes. Cut-off voltage at the low end held at the expected threshold with no premature shutdown.
• Fuel gauge IC reset after swap: After fitting this cell, place the watch on its magnetic charger immediately and charge to 100% before first use. The fuel gauge IC on the SW1002 loses its charge reference when the cell is removed — without a full charge cycle from near-zero, the percentage readout will be inaccurate from the first boot.

Why the Alpha SW1002 battery drains faster with always-on display and continuous heart rate active

The SW1002's flexible AMOLED panel and optical HR sensor together draw significantly more current than either feature alone. Always-on display keeps the panel lit at a reduced brightness, but the current is constant. Continuous heart rate polling adds a pulsed LED load on top of that. On a 450mAh cell, running both simultaneously shortens charge intervals noticeably — switching HR to on-demand in the watch settings is the most effective way to extend time between charges.

Watch not pairing to phone after battery replacement

Removing the battery cuts power to the BLE radio and clears the active pairing session. The watch retains its Bluetooth address in flash, but the phone's OS marks the device as disconnected and sometimes drops the bond entirely. If the watch does not reconnect automatically, open your phone's Bluetooth settings, forget the Alpha SW1002, then re-pair from scratch through the companion app. The watch must be at least 20% charged before initiating a new pairing — the BLE stack on this platform will not complete bonding below that threshold.