Huawei G7002 Smartwatch Compatible Battery HBC80S 3.7V 800mAh

Huawei Fit G7002 Series — 3.7V Li-ion Replacement Battery (HBC80S / HBC85S)

This is a 3.7V, 800mAh Li-ion cell for the Huawei Fit G7002 smartwatch and compatible wearables in the same family. It replaces the original cell when the watch no longer holds charge, shuts down unexpectedly, or fails to power on. Dimensions are 54.50 × 34.10 × 4.50mm — confirm against your existing cell before fitting.

• G7002, C288S, C2205, C2285 and related models: These watches share the same battery bay dimensions, connector pitch, and fuel gauge IC protocol. One cell covers all of them — the BMS handshake and charge termination voltage are consistent across the range.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on compatible hardware. The BMS accepted charge correctly, hit cutoff at the expected 4.2V ceiling, and held voltage through a standard discharge sweep without triggering premature protection trips.
• Fuel gauge recalibration on first use: On first installation, let the watch discharge to auto-shutoff, then charge uninterrupted to 100%. This gives the fuel gauge IC one complete cycle against the new cell's discharge curve before it starts reporting percentages — skipping this step causes erratic percentage readings for the first several days.

Why the Huawei Fit reports wrong battery percentage after a cell swap

The Fit uses a coulomb-counter fuel gauge IC that builds its discharge model against the original cell over time. When you fit a new cell, the IC is still running the old model — the curve no longer matches the actual cell chemistry. The watch will show inflated or deflated percentages until the IC re-maps. One full discharge-to-shutoff followed by a complete uninterrupted charge cycle resets the baseline. After that single cycle, percentage readings stabilise.

Watch shuts down at 20–30% with no warning

This is a voltage-cliff failure — not a capacity problem. Under the load spike from the display backlight or GPS polling, the cell voltage dips sharply below the BMS cutoff threshold even though the fuel gauge still reads 20–30%. It typically means the original cell has lost internal resistance tolerance, not total capacity. Fit the replacement cell and run the full recalibration cycle above. If the symptom persists on the new cell, check that the connector is fully seated — a high-resistance contact at the flex connector mimics this exact failure at the same percentage band.