Poco X4 GT BM5G Compatible Battery 3.87V 4950mAh

Poco X4 GT — 3.87V Li-Polymer Replacement Battery (BM5G)

This is a 3.87V, 4950mAh Li-Polymer cell built to the BM5G specification for the Poco X4 GT smartphone. It replaces the original cell when capacity has dropped, the phone shuts down unexpectedly, or the battery no longer holds a usable charge. Rated at 19.16Wh, it restores full device function at the same voltage and physical footprint as the factory cell.

• X4 GT fit: The X4 GT uses a dedicated connector layout and a BMS that handshakes with the Dimensity 8100 power management IC. The BM5G cell matches that connector pinout, cell impedance range, and charge termination voltage — so the fuel gauge IC accepts it without throwing a battery error flag.
• Bench tested on actual hardware: We cycled this cell on the X4 GT platform, monitoring BMS handshake, charge termination at 4.40V, and low-voltage cutoff behaviour. The protection circuit tripped correctly at the expected floor and recovery charging resumed without manual intervention.
• First-cycle calibration on the X4 GT: After installation, disable fast charging for one full discharge-charge cycle. The fuel gauge IC is still calibrated to the old cell's discharge curve. One slow cycle lets the coulomb counter remap to the new cell before high-current fast charging pushes current into an uncalibrated state.

Why the X4 GT reports wrong battery percentage after a cell swap

The X4 GT uses a coulomb counter and a stored discharge curve to calculate the percentage shown on screen. When a new cell goes in, that stored curve still reflects the old, degraded cell. The mismatch causes the OS to report inflated or deflated percentages until the IC collects fresh data. One complete discharge to auto-shutdown and a full charge to 100% without interruption resets the curve and brings the reading back into accurate range.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC has not yet recalibrated the voltage-to-percentage mapping for the new cell. The X4 GT's modem and display draw sharp current spikes that cause cell voltage to sag briefly below the shutdown threshold — even though the reported percentage still looks safe. The phone reads that voltage dip as a critical low and cuts power immediately. Run one full uninterrupted discharge-to-shutdown cycle, then charge straight to 100% — this resets the cutoff mapping and eliminates the premature shutdown.