About this replacement
Amazfit GTR 4 47mm — 3.87V Li-Polymer Replacement Battery (PL412631)
This is a 3.87V, 470mAh lithium-polymer cell for the Amazfit GTR 4 47mm smartwatch. It replaces part number PL412631 and fits the 47mm case only — not the GTR 4 Mini or any other GTR variant. Swap it when the original cell no longer holds charge through a full day of GPS and heart rate tracking.
- GTR 4 47mm fit: The GTR 4 47mm uses a dedicated cell footprint — 31.40 x 25.90 x 4.00mm — with a specific flex connector keyed to the watch's power management IC. Only cells matching PL412631's dimensions and connector pinout will seat correctly without stressing the ribbon cable.
- Bench tested on actual hardware: We ran the cell through charge and discharge cycles on the GTR 4 platform and confirmed the BMS accepted the new cell without throwing a low-voltage lockout or refusing the charge handshake at the PMIC.
- Post-swap charge calibration: After fitting this cell, place the watch on its magnetic charger immediately and charge it to 100% before using it. The GTR 4's fuel gauge IC loses its reference point when the old cell is disconnected — without a full charge cycle from near-zero, the percentage readout will be inaccurate for days.
Why the GTR 4 fuel gauge reads wildly wrong after a cell swap
The GTR 4 uses a coulomb-counting fuel gauge IC that tracks charge state by measuring current flow in and out of the cell over time. When you disconnect the old battery, the IC loses that accumulated reference entirely. It then estimates state-of-charge from open-circuit voltage on the new cell, which gives a rough and often wrong starting number. A single full charge cycle — from near-zero to 100% without interruption — lets the IC reset its baseline and restore accurate readings.
Magnetic charge contacts not connecting after reassembly
If the watch sits on the charger but shows no charging indicator, the rear contact pads have likely shifted during back-cover reassembly. Even a fraction of a millimetre of misalignment breaks the magnetic contact circuit. Remove the back cover, reseat the battery connector fully, and refit the cover so all four corner clips engage flush. Then place the watch on the charger and confirm the charging icon appears within five seconds.