ZTE Nubia M2 Li3936T44P6h836542 Replacement Battery 3.85V 3600mAh

ZTE Nubia M2 / NX551J — 3.85V Li-Polymer Replacement Battery (Li3936T44P6h836542)

This is a 3.85V, 3600mAh Li-Polymer cell built to the same OEM specification as the factory battery in the ZTE Nubia M2 and Nubia M2 Dual SIM (NX551J). It fits all Nubia M2 variants — including the TD-LTE model — that use part number Li3936T44P6h836542. Voltage, connector pinout, and BMS handshake match the originals.

• Nubia M2 variant coverage: The standard M2, Dual SIM, and Dual SIM TD-LTE all share the same battery bay geometry, connector, and 3.85V nominal rail. One cell covers the full NX551J lineup because ZTE used a single battery platform across the variants — no model-specific BMS tuning separates them.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on an NX551J board. The BMS accepted the full 3600mAh charge without triggering a protection cutoff, and the fuel gauge IC registered a valid cell handshake on first contact.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before the coulomb counter locks in its baseline — skipping this step causes erratic percentage readings early on.

Sudden shutdown at 20–30% on the Nubia M2 after a cell swap

This is a voltage-cliff problem, not a cell defect. A fresh Li-Polymer cell has a steeper voltage drop in the lower state-of-charge band than the worn cell the fuel gauge was calibrated to. When the modem fires a high-power burst or the screen peaks brightness, the new cell's voltage dips below the BMS protection threshold momentarily — the phone cuts out even though the gauge still shows charge remaining. The fix is one full discharge cycle without fast charging. Once the fuel gauge IC has mapped the new cell's actual voltage curve, the shutdown threshold aligns correctly and the drop-outs stop.

USB fast charge not activating after fitting the replacement cell

The Nubia M2's charge IC negotiates fast-charge protocol on the first cycle using BMS state data from the previous session. A new cell presents no prior session data, so the charge IC defaults to standard 5V/1A as a safety measure. This is normal behaviour — not a fault with the replacement cell or the charger. Plug in the original charger, let the phone complete one full charge cycle at standard rate, then disconnect and reconnect. On the second connection the charge IC will renegotiate and fast charging will activate.