Meizu M2 Replacement Battery BT43C 3.8V 2400mAh Li-Polymer

MeiZu M2 Series — 3.8V Li-Polymer Replacement Battery (BT43C)

This is a 3.8V, 2400mAh Li-Polymer cell built to the BT43C specification. It fits the MeiZu M2, M578CA, M578CE, M578, and four additional M578 variants. Swap it in when the original cell no longer holds charge or the phone shuts down unexpectedly under load.

• M2 and M578 platform fit: The M2 and M578 variants share the same physical footprint, flex connector pinout, and charge IC communication protocol — one cell covers all of them without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on M2 hardware. The BMS handed off correctly to the phone's charge IC, and the protection circuit tripped at the expected over-discharge threshold without nuisance cutoffs at normal load.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one full discharge-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging is applied to an uncalibrated cell.

Why the M2 reports wrong battery percentage after a cell swap

The M2 uses a coulomb counter that was trained against the original cell's impedance and discharge curve. A new cell has different internal resistance, so the stored calibration data no longer matches real charge state. The phone reads voltage and maps it to a percentage based on outdated reference points. One complete discharge to automatic shutdown — followed by a full charge to 100% — resets the reference and aligns the readout with actual capacity.

Sudden shutdown at 20–30% on the replacement cell

This happens when the modem or display pulls a surge of current and the cell voltage drops sharply — below the protection circuit's cutoff — even though the percentage display looks safe. On a freshly installed, uncalibrated cell, the fuel gauge IC does not yet know where the real voltage cliff sits. The BMS sees the sag as a fault and cuts power before the OS can react. Let the phone complete one full unconstrained cycle, then check: if shutdown still occurs at 25% or above, confirm the resting cell voltage reads above 3.6V with a multimeter before reinstalling.