Google Pixel Watch GC15S GDHB7 Compatible Battery 3.85V 1600mAh

Google Pixel 9 Pro Fold / GC15S — 3.85V Li-Polymer Replacement Battery (GDHB7)

This is a 3.85V, 1600mAh Li-Polymer cell that replaces the original GDHB7 battery in the Google Pixel Watch GC15S and GGH2X, and the Pixel 9 Pro Fold. It restores power to devices where the original cell has degraded, swollen, or failed to hold charge. Voltage and capacity match OEM spec exactly.

• GC15S, GGH2X, and Pixel 9 Pro Fold compatibility: All three models share the GDHB7 cell specification — same 3.85V nominal voltage, same connector pinout, and the same BMS handshake protocol used by Google's charge IC. Swapping between these models does not require any firmware or hardware change.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Pixel Watch unit. The BMS accepted the cell without fault flags, held the cutoff voltage cleanly at the top of charge, and triggered low-voltage protection at the correct floor rather than hard-cutting mid-cycle.
• Fuel gauge recalibration on first cycle: On first use after installation, disable fast charging and run one full discharge-to-charge cycle at standard rate. This lets the fuel gauge IC build an accurate discharge curve against the new cell before high-current charging starts pushing current into an uncalibrated state.

Why the Pixel Watch reports wrong battery percentage after a cell swap

Google's fuel gauge IC uses a coulomb counter calibrated against the original cell's charge curve. When a new cell goes in, the stored curve no longer matches the actual discharge profile of the replacement. The gauge reads from the old map and reports percentages that drift — showing 40% while the cell is actually at 25%, or vice versa. One complete discharge cycle from 100% to automatic shutdown, followed by a full charge, forces the IC to reset its learned curve against the new cell.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage cliff, not a capacity issue. Under display or sensor load, cell voltage drops faster than the gauge expects — the protection circuit sees voltage fall below its trip threshold and cuts power before the percentage readout reaches zero. It happens most often in the first few cycles before the fuel gauge IC has recalibrated. Run the full discharge-recalibration cycle described above, and confirm the cell is holding above 3.5V under moderate load using a battery stats app.