Meitu M4 Replacement Battery MA4002 3.8V 2100mAh

Meitu M4 — 3.8V Li-Polymer Replacement Battery (MA4002)

This 3.8V, 2100mAh lithium-polymer cell replaces the original MA4002 battery in the Meitu M4 smartphone. It restores power to the display, processor, and connectivity hardware when the original cell has degraded or failed to hold a charge. Capacity and voltage match the factory specification exactly.

• Meitu M4 fit: The M4 uses a fixed connector pinout and BMS handshake tied to the MA4002 part number. This cell matches that pinout, so the phone's charge IC and fuel gauge IC register the battery correctly on first boot.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the M4 platform. The BMS accepted the cell without fault codes, and the charge IC completed a full constant-current to constant-voltage charge sequence without interruption.
• Fuel gauge recalibration on first cycle: 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 its coulomb counter against the new cell's discharge curve before higher charge rates are applied to an uncalibrated cell.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC is still calibrated to the old cell's voltage curve. A new cell holds a steeper voltage cliff near the lower end of its charge window, so the phone hits a real low-voltage cutoff before the percentage readout catches up. The modem and display together pull enough current to collapse cell voltage below the BMS threshold in milliseconds. Run one full discharge to automatic shutdown, then charge uninterrupted to 100% — after that cycle the fuel gauge recalibrates and shutdowns at partial percentages stop.

Phone warm near the battery during the first few charges

A new lithium-polymer cell starts with slightly higher internal impedance than a broken-in cell. The charge IC pushes constant current into that higher-impedance cell, and the extra resistive loss appears as heat in the battery zone. This is normal for the first two to three cycles and reduces as impedance drops with use. If warmth continues beyond the third full charge cycle, check that the phone is not simultaneously running a data-heavy background process during charging, which adds load on top of the charge current.