Xiaomi Pocophone F1 BM4E Replacement Battery 3.85V 3900mAh

Xiaomi Pocophone Poco F1 — 3.85V Li-Polymer Replacement Battery (BM4E)

This is a 3.85V, 3900mAh Li-Polymer replacement battery for the Xiaomi Pocophone Poco F1, including the Armoured Edition Global Dual SIM variants (M1805E10A). It slots directly into the Poco F1 chassis and connects to the same BMS harness as the original BM4E cell. Swap it when the original cell can no longer hold a full charge or shuts down unexpectedly under load.

• Poco F1 and Armoured Edition compatibility: All listed variants — standard, Armoured Edition, and TD-LTE — share the same BM4E cell footprint, connector pinout, and BMS handshake protocol. One cell fits every variant without modification.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the Poco F1 board. The BMS accepted the cell without fault flags, current draw tracked normally through the Snapdragon 845 load cycle, and the fuel gauge IC responded correctly to state-of-charge reporting.
• First-cycle fast charge protocol: On first use after installation, disable Qualcomm Quick Charge in the developer settings and complete one full discharge-charge cycle at standard rate. This lets the fuel gauge IC recalibrate its coulomb counter against the new cell's discharge curve before high-current fast charging is applied to an uncalibrated cell.

Why the Poco F1 reports wrong battery percentage after a cell swap

The Poco F1 uses a coulomb counter in the PMIC to track charge in and out of the cell. When you replace the cell, the counter's learned curve — built against the old degraded cell — no longer matches the new cell's actual voltage-to-capacity relationship. The phone's OS reads this mismatch and reports percentages that jump or plateau incorrectly. One complete discharge below 5% followed by a slow full charge resets the learned curve and restores accurate reporting.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC is still calibrated to the old cell's depleted voltage curve. The replacement cell hits a steeper voltage drop under modem and display load at the same state-of-charge point, and the BMS trips a undervoltage cutoff before the gauge reads zero. It is not a faulty cell. Run two full discharge-charge cycles without Quick Charge enabled — the PMIC recalibrates the cutoff threshold against the new cell's actual voltage floor, which sits closer to 3.4V under load.