Motorola QB50 Replacement Battery XT2347 3.91V 4850mAh

Motorola Moto G84 5G / XT2347 — 3.91V Li-Polymer Replacement Battery (QB50)

This is a 4850mAh Li-Polymer cell at 3.91V, built to replace the original QB50 battery in the Motorola XT2347 and Moto G84 5G. The original cell degrades over charge cycles and loses the ability to sustain voltage under screen and modem load. This replacement restores full charge capacity to the XT2347 platform.

• XT2347 and Moto G84 5G fit: Both model designations share the same battery bay geometry, connector pinout, and BMS handshake protocol. The QB50 part number covers both — there is no separate variant between the two.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on XT2347 hardware. The BMS accepted the cell without error flags, and the fuel gauge IC tracked state of charge without erratic jumps once calibration completed.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle. This lets the fuel gauge IC build a discharge curve against the new cell before high-current charging begins on an uncalibrated cell.

Sudden shutdown at 20–30% on the Moto G84 5G after a cell swap

The XT2347 shuts down mid-use because the modem and display together draw enough current to collapse cell voltage below the BMS cutoff threshold — even when the fuel gauge still reads 20–30%. This happens because the fuel gauge IC is still calibrated to the old cell's discharge curve. The new cell hits its voltage floor faster under load than the old curve predicts. One full discharge-charge cycle with fast charging disabled lets the coulomb counter recalibrate, and the shutdowns stop.

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

After installing a new cell, the charge IC on the Moto G84 5G may default to standard 5V charging and refuse to negotiate the higher USB-PD voltage on the first cycle. This is a protective behaviour — the charge IC withholds high-current negotiation until it has confirmed the new BMS is responding correctly. Plug into the original Motorola charger and let the first charge complete at standard rate. On the second cycle, USB-PD fast charge should negotiate normally at the expected voltage handshake.