Poco F3 GT 5G Replacement Battery 3.87V 4900mAh

Poco F3 GT 5G (M2104K10I) — 3.87V Li-Polymer Replacement Battery

This is a 3.87V, 4900mAh (18.96Wh) Li-Polymer cell for the Poco F3 GT 5G (model M2104K10I). It replaces the original internal battery when the device shuts down early, holds charge poorly, or swells after heavy use. Dimensions are 85.45 × 62.00 × 5.60mm — verify against your existing cell before installation.

• F3 GT 5G and M2104K10I compatibility: Both model identifiers refer to the same hardware revision. The battery connector, BMS pinout, and physical envelope are identical across both — one cell fits either designation.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the F3 GT 5G platform. The BMS handshake completed without fault codes, and the charge IC accepted the cell without thermal events across full-rate charging.
• Fuel gauge recalibration after swap: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle at standard rate. This lets the coulomb counter recalibrate against the new cell's discharge curve before high-current charging pushes into an uncalibrated state.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage cliff issue, not a capacity issue. Under sustained modem or display load, a new cell with an uncalibrated fuel gauge IC can hit the BMS low-voltage cutoff while the OS still reads 20–30% remaining. The phone cuts out because the cell voltage drops below 3.2V under load, even though the coulomb counter hasn't caught up. Run one full discharge cycle without fast charging to resync the fuel gauge to the actual cell curve.

USB-PD fast charge not activating on first cycle after replacement

After a cell swap, the charge IC may default to trickle or standard charge on the first cycle while it assesses the new cell's impedance. This is normal BMS behaviour — the controller won't negotiate full fast-charge current until it establishes a baseline. Do not assume the cable or adapter is at fault. Allow the first full charge cycle to complete at standard rate, then fast charging will resume on subsequent cycles once the IC has profiled the new cell.