Nubia N2 Li3950T44P6h856751 Replacement Battery 3.85V 4900mAh

Nubia N2 / NX575J — 3.85V Li-Polymer Replacement Battery (Li3950T44P6h856751)

This is a 3.85V, 4900mAh (18.87Wh) Li-Polymer cell for the Nubia N2, N2 Dual SIM, N2 Dual SIM TD-LTE, and NX575J smartphones. It replaces OEM part Li3950T44P6h856751 when the original cell degrades, swells, or can no longer hold a usable charge. Dimensions are 83.56 x 67.30 x 4.74mm — verify against the original before fitting.

• N2 and NX575J platform fit: All four listed models run the same 3.85V voltage rail and share the same connector pinout and BMS handshake protocol. One cell part number covers the full variant lineup, including both single and Dual SIM TD-LTE configurations.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the N2 platform. The BMS accepted charge handshake on the first connection, balancing kicked in correctly at top-of-charge, and no thermal events occurred across three full cycles.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate against the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell — preventing early percentage drift or sudden shutdowns.

Why the Nubia N2 reports wrong battery percentage after a cell swap

The N2 uses a coulomb counter and a stored discharge curve to calculate the percentage shown on screen. When you swap the cell, the fuel gauge IC still references the old cell's curve. The new 4900mAh cell has a slightly different voltage-to-capacity profile, so the reported percentage drifts early or reads high before a sudden drop. One full slow discharge down to automatic shutdown, followed by a full charge to 100%, resets the counter against the new curve.

Sudden shutdown at 20–30% on the replacement cell

This happens when the modem or screen pulls a current spike that the cell cannot sustain, causing voltage to sag below the BMS cutoff threshold — even though the gauge still reads 20–30%. It is a calibration issue, not a faulty cell. The fuel gauge IC is cutting out on a voltage cliff it hasn't mapped yet on the new cell. Run one full slow-charge cycle without fast charging; after that the IC learns the actual voltage floor and the shutdowns stop above 3.4V under load.