About this replacement
MeiZu 15 Series — 3.85V Li-Polymer Replacement Battery (BA881)
The BA881 is a 3.85V, 2900mAh Li-Polymer cell that fits the MeiZu 15, 15 Dual SIM, 15 Dual SIM TD-LTE, and M881Q smartphones. It replaces the original cell when capacity has dropped and the phone can no longer hold a useful charge through a typical day. Capacity figures are taken from product data — 11.17Wh total energy.
- M881Q and 15 series compatibility: These variants share the same battery bay dimensions, connector pinout, and BMS handshake protocol. The BA881 fits all four models without modification — the same 3.85V nominal rail and cell footprint (68.70 × 61.40 × 3.90mm) runs across the entire lineup.
- Bench tested on actual hardware: We cycled the BA881 through charge and discharge on the 15 platform and logged BMS communication. The protection circuit engaged correctly at both high-voltage cutoff and low-voltage floor, and the fuel gauge IC accepted the cell without error flags on the first full cycle.
- First-cycle fast charge protocol: On first use after installation, disable fast charging and run one complete discharge-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging pushes into an uncalibrated state.
Sudden shutdown at 20–30% on the MeiZu 15 after a cell swap
This happens because the fuel gauge IC is still running a lookup table calibrated to the old, degraded cell. A new cell has a steeper voltage cliff at low state-of-charge, so the phone hits the hardware undervoltage cutoff before the OS percentage reaches zero. The fix is one full discharge to automatic shutdown followed by a complete charge to 100% without interruption. After that cycle, the coulomb counter resets its reference points against the new cell's actual curve.
OS percentage jumping erratically after BA881 installation
Erratic percentage jumps — often 5–15% in either direction without load change — point to the fuel gauge IC recalibrating in real time against an unfamiliar cell. The IC's stored charge curve no longer matches the new cell's impedance and discharge profile. Run two full discharge-charge cycles at standard charge rate with the screen on during discharge to accelerate recalibration. By the end of the second cycle, reported percentage should track smoothly and stabilise above 3.6V at the 20% mark.