Meizu M1 BT42 Compatible Battery 3.8V 3100mAh Li-Polymer

MeiZu M1 / Note — 3.8V Li-Polymer Replacement Battery (BT42)

This is a 3.8V, 3100mAh lithium-polymer replacement cell for the MeiZu M1 and M1 Note smartphones. It swaps the original BT42 battery when the existing cell has degraded to the point of unreliable use. Physical dimensions are 75.72 × 60.32 × 4.10 mm — measure your bay before ordering if you are unsure of your variant.

• M1 and M1 Note compatibility: Both models share the BT42 footprint, connector pinout, and the same 3.8V nominal rail required by the Mediatek SoC power management IC. No hardware modification is needed for either device.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on M1 hardware and confirmed the BMS communicates correctly with the charge IC — no runaway charge condition, and cutoff triggers cleanly at the low-voltage threshold.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before the system begins making capacity predictions against it.

Sudden shutdown at 20–30% on the MeiZu M1 after a cell swap

This happens because the fuel gauge IC retains the discharge curve of the old cell in its coulomb counter registers. When the new cell's actual voltage under modem or display load drops faster than the model predicts, the system hits a hard cutoff before the reported percentage reaches zero. The IC interprets a voltage cliff as an emergency, not an empty gauge. One full discharge cycle — letting the phone shut off on its own without intervention — allows the coulomb counter to re-anchor to the new cell's actual capacity.

MeiZu M1 not powering on after the replacement battery sat in storage

Li-polymer cells in storage self-discharge over time. If the cell has dropped below approximately 2.5V per cell, the BMS enters a lockout state and refuses to supply current to protect against an unsafe charge condition. The phone will show nothing — no boot logo, no charging animation. Connect to a wall charger rated at 5V and leave it for 20–30 minutes without pressing any buttons; most BMS circuits include a trickle pre-charge path that slowly raises cell voltage back above the recovery threshold before handing off to the main charge IC.