About this replacement
Navon Mizu M450 — 3.8V Li-ion Replacement Battery (G55134)
This is a 3.8V, 1750mAh Li-ion battery for the Navon Mizu M450 and Mizu M450 Dual SIM smartphones. It replaces OEM part number G55134. Fits both single and dual SIM variants — same cell format, same connector, same BMS handshake requirements.
- M450 and M450 Dual SIM compatibility: Both handset variants use identical battery dimensions (65.50 × 53.85 × 4.36 mm) and the same 3.8V charging rail. The BMS communication protocol does not differ between the two SKUs, so one cell fits both without modification.
- Bench tested on actual hardware: We cycled this cell through a full discharge and charge sequence, confirmed the BMS accepted the charge IC handshake correctly, and verified cutoff voltages at both ends of the curve — no runaway charging, no premature low-voltage lockout.
- Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-charge cycle at standard rate. This allows the fuel gauge IC to map the new cell's discharge curve before high-current charging is introduced into an uncalibrated state.
Sudden shutdown at 20–30% on the Mizu M450
This is a voltage cliff issue, not a capacity issue. When the modem transmits or the screen peaks in brightness, load current spikes sharply. An aged or freshly swapped cell that hasn't been calibrated yet cannot sustain voltage under that spike, and the protection circuit cuts power before the OS can log a graceful shutdown. The fuel gauge IC still reports 20–30% because it hasn't learned the new cell's actual voltage-to-charge curve. One full discharge-charge cycle at standard rate resolves this in most cases.
OS reporting wrong battery percentage after cell swap
The Mizu M450's fuel gauge IC uses a coulomb counter calibrated against the discharge curve of the original cell. When a new cell goes in, the stored curve no longer matches reality — the phone reads percentage from stale data. You'll see the percentage jump or stall at fixed points during discharge. Drain the battery until the phone shuts off on its own, then charge uninterrupted to 100% without fast charging enabled — after that single cycle, the coulomb counter resets its reference points against the new cell.