About this replacement
Huawei Watch GT4 41mm — 3.87V Li-Polymer Replacement Battery (HB572727EFW)
This 490mAh (1.9Wh) Li-Polymer cell is a direct replacement for the Huawei Watch GT4 41mm. It restores power to the display, heart rate sensor, GPS, and BLE radio when the original cell has degraded or failed to hold a charge. Voltage matches the watch's 3.87V power rail exactly.
- GT4 41mm platform fit: The 41mm GT4 uses a smaller chassis than the 46mm variant, with a distinct cell footprint of 25.60 × 25.00 × 5.40mm. The HB572727EFW matches that footprint. Fitting a 46mm cell here will not work — the connector pitch and cell dimensions differ.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the GT4 41mm platform. The BMS accepted the cell without error flags, and the fuel gauge IC registered correctly after a full charge cycle from near-zero.
- Fuel gauge calibration after swap: Place the watch on its magnetic charger immediately after fitting this cell and charge to 100% before first use. The fuel gauge IC on this platform loses its reference point when the original cell is removed. Without a full charge cycle from near-zero, the gauge will report inaccurate percentages for days.
BLE session loss after battery removal on the GT4 41mm
Cutting power to the GT4 41mm during a cell swap drops the active Bluetooth session stored in the watch's memory. The watch does not automatically re-establish pairing with the phone — it treats itself as a new device. Open the Huawei Health app, navigate to device settings, remove the watch, then re-pair it from scratch. The watch MAC address stays the same, so health data and settings stored in the app are not lost.
Watch shows 0% and will not power on immediately after swap
This is a fuel gauge IC issue, not a faulty cell. When the original battery is disconnected, the IC loses its charge reference and defaults to 0%. The watch may refuse to boot because it reads the battery as critically empty, even though the new cell has residual charge. Place it on the charger for at least 15 minutes until the display shows a charging indicator, then allow it to reach 100% before use. Do not attempt a hard reset until the gauge has completed one full charge cycle from below 5%.