About this replacement
MeiZu MX4 Pro — 3.8V Li-Polymer Replacement Battery (BT41)
This is a 3.8V, 3350mAh Li-Polymer replacement battery for the MeiZu MX4 Pro smartphone. It fits models MX4 Pro, MX4SWDS0, and M462U. OEM part numbers BT41, N0004720, and US525972H4 all cross-reference to this cell.
- MX4 Pro, MX4SWDS0, M462U compatibility: These three models share the same 3.8V power rail, physical connector, and BMS handshake protocol. The cell dimensions — 69.85 × 58.20 × 4.54 mm — match the original chassis cavity without modification.
- Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the MX4 Pro platform. The BMS accepted the new cell without triggering an over-voltage or under-voltage cutoff event.
- First-cycle fuel gauge reset: After installing this cell, disable fast charging and run one complete discharge down to auto-shutdown, then charge to 100% uninterrupted. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging begins.
Sudden shutdown at 20–30% on the MX4 Pro after a cell swap
The MX4 Pro's fuel gauge IC retains the discharge curve of the old, degraded cell in its coulomb counter. When the new cell hits a voltage point that the IC maps to "empty," it triggers a shutdown — even though actual capacity remains. This is not a defective cell. One full uninterrupted discharge-charge cycle forces the IC to re-learn the voltage-to-capacity curve of the new cell. After that cycle, reported percentage aligns with real state of charge.
MeiZu MX4 Pro not powering on after storage with a low or flat battery
Li-Polymer cells that drop below approximately 2.5V per cell trigger a BMS lockout to prevent catastrophic discharge damage. The phone will show no signs of life — no boot screen, no charge indicator. Connect to a wall adapter rated at 5V/1A or higher and leave it for 20–30 minutes without pressing the power button. The BMS recovery circuit needs a trickle current to bring the cell voltage above the lockout threshold before the phone will respond. Once the charge LED activates, normal charging has resumed.