Nubia N1 Replacement Battery 3.85V 4900mAh Li3849T44P6h956349

Nubia N1 / NX541J — 3.85V Li-Polymer Replacement Battery (Li3849T44P6h956349)

This is a 3.85V, 4900mAh lithium-polymer cell for the Nubia N1 (NX541J) smartphone. It replaces OEM part Li3849T44P6h956349 and fits the same physical bay with the same connector. At 18.87Wh, it matches the original energy specification exactly.

• N1 and NX541J compatibility: Both model numbers refer to the same hardware platform. The N1 was sold under the NX541J designation in several markets. The battery bay dimensions, connector pinout, and BMS handshake requirements are identical across both variants.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the N1 platform. The BMS accepted the cell without triggering low-voltage lockout, and the charge IC cycled through CC and CV phases cleanly at standard current.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-charge cycle at standard current. This lets the fuel gauge IC map the new cell's discharge curve before the coulomb counter begins reporting percentage to the OS. Skipping this step is the primary cause of erratic percentage readings after a cell swap.

Sudden shutdown at 20–30% on the Nubia N1 after a cell swap

The N1's fuel gauge IC retains the discharge curve learned from the original cell. When a new cell is installed, the IC's stored curve no longer matches the actual voltage-to-capacity relationship of the replacement. Under load spikes — screen-on, active LTE, or GPS — the cell voltage drops sharply at the low end of the curve, and the IC reads a hard cutoff before the displayed percentage reaches zero. This is a calibration gap, not a cell defect. Run one full discharge to below 5% followed by an uninterrupted charge to 100% at standard current. After that cycle the fuel gauge recalibrates and the premature shutdowns stop.

Phone won't power on after the replacement cell sat in storage

Li-polymer cells self-discharge in storage. If this battery shipped or sat unused at or below 2.5V per cell, the BMS enters a protective lockout state and blocks normal charging current. The phone will show nothing — no charging animation, no boot. Connect the device to a wall adapter, not a PC port, and leave it for 20–30 minutes without pressing the power button. Wall adapters deliver enough trickle current to bring the cell above the BMS re-enable threshold of approximately 2.7V per cell. Once the charging indicator appears, the BMS has exited lockout and normal charging resumes.