Poco M7 Pro 5G Replacement Battery BN5U 3.91V 5000mAh

Poco M7 Pro 5G — 3.91V Li-Polymer Replacement Battery (BN5U)

The BN5U is a 3.91V, 5000mAh lithium-polymer cell that fits the Poco M7 Pro 5G. It replaces the original battery when the phone can no longer hold charge, shuts off unexpectedly, or drains too fast to be useful. Capacity is 19.55Wh, matching the OEM specification.

• M7 Pro 5G cell match: The BN5U uses the same 3.91V nominal voltage and connector pinout as the factory cell. The phone's charge IC and fuel gauge IC communicate with the battery over the same BMS interface — no software rejection on installation.
• Bench tested on actual hardware: We cycled the BN5U through charge and discharge on the M7 Pro 5G platform. The BMS accepted the cell without a protection trip, and the fuel gauge began tracking state-of-charge correctly after one full cycle.
• Fuel gauge recalibration on first use: After fitting the BN5U, disable fast charging and run one complete discharge-to-charge cycle at standard rate. This lets the fuel gauge IC map its coulomb counter against the new cell's discharge curve before high-current fast charging begins pushing current into an uncalibrated state.

Sudden shutdown at 20–30% on the Poco M7 Pro 5G

A fresh lithium-polymer cell has a steeper voltage curve at the low end than a worn cell. The fuel gauge IC on the M7 Pro 5G is still calibrated to the old cell, so it reads 25% when the new cell is actually closer to the cutoff voltage under modem and display load. The phone shuts down not because the battery is faulty, but because the gauge is reading from the wrong curve. One full discharge cycle — letting the phone run down to automatic shutdown, then charging uninterrupted to 100% — resets the coulomb counter and fixes the cutoff point.

USB-PD or fast charge not triggering after fitting the BN5U

On the first charge cycle after a cell swap, the charge IC may default to trickle or standard rate while it verifies the new cell's internal resistance and BMS handshake. This is normal behaviour, not a fault in the replacement battery. Fast charge protocols — including Xiaomi's own HyperCharge — typically re-enable after the first full charge completes and the BMS has logged one valid cycle. If fast charge still does not appear after that cycle, check that the charger output is at least 18W and the cable supports high-current data lines.