Huawei Watch GT 46mm Replacement Battery HB512627ECW+ 3.82V 420mAh

Huawei Watch GT 46mm — 3.82V Li-Polymer Replacement Battery (HB512627ECW+)

This 3.82V, 420mAh Li-Polymer cell is a direct replacement for the Huawei Watch GT 46mm (FTN-B19). It restores power to the smartwatch after the original cell has degraded and can no longer hold a charge through a full day of use. Capacity is 420mAh (1.6Wh), matching the OEM specification.

• Watch GT 46mm and FTN-B19 fitment: Both model references use the same 26.40 × 25.30 × 5.10mm cell cavity, the same flex connector, and the same BMS handshake over the protection circuit. One cell covers both variants.
• Bench tested on actual hardware: We ran this cell through the GT 46mm charge controller and confirmed the BMS accepted the new cell without tripping low-voltage lockout. Protection circuit cut in cleanly at the expected threshold with no fault flags.
• Post-swap charge cycle: 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 GT 46mm cannot calibrate its state-of-charge reference without a full charge cycle from near-zero following a cell swap. Skipping this step causes the display to read inaccurate percentages from the first boot.

Why the GT 46mm fuel gauge reads incorrectly after a cell swap

The GT 46mm uses a coulomb-counting fuel gauge IC that tracks charge by measuring current flow over time. When the cell is removed, that running count is lost. The IC wakes with no reference point and estimates state-of-charge from the open-circuit voltage of the new cell. A brand-new Li-Polymer cell at rest sits near 3.8V, which maps to roughly 50–60% on most fuel gauge tables — so the watch may show a misleading mid-range figure on first boot. A full charge cycle from near-zero resets the calibration and aligns the gauge to the actual cell capacity.

Watch not pairing to the Huawei Health app after battery replacement

Removing the battery cuts power to the BLE stack completely, which clears the active pairing session stored in volatile memory. The phone retains its saved device record, but the watch wakes with no matching session — so the Huawei Health app shows the device as unavailable or stuck on "connecting." Open the Huawei Health app, go to the device settings, select "Unpair device," then re-initiate the pairing process from scratch. The watch will generate a new pairing code and restore the connection.