MeiZu BT50 Blue Charm Metal Replacement Battery 3.8V 3100mAh

MeiZu Blue Charm Metal / Meilan Metal — 3.8V Li-Polymer Replacement Battery (BT50)

This is a 3.8V, 3100mAh Li-Polymer cell that replaces the BT50 battery in the MeiZu Blue Charm Metal, Meilan Metal, Blue Charm Metal Dual SIM TD-LTE, and M57A. It restores power to the processor, display, and wireless radios when the original cell has degraded past useful capacity. Voltage and dimensions match the OEM cell exactly: 72.65 × 62.85 × 4.25 mm.

• Blue Charm Metal / Meilan Metal platform fit: These model variants share the same battery bay dimensions, connector orientation, and BMS handshake protocol — the BT50 part number covers all of them without modification.
• Bench tested on actual hardware: We ran the cell through charge and discharge cycles on a Blue Charm Metal unit. The BMS accepted charge immediately, voltage held steady under display and modem load, and no thermal anomalies appeared at the charge IC.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and complete one full discharge-charge cycle at standard current. This lets the fuel gauge IC map its coulomb counter against the new cell's discharge curve before high-current charging pushes current into an uncalibrated state.

Sudden shutdown at 20–30% on the Blue Charm Metal after a cell swap

A fresh Li-Polymer cell has a steeper voltage cliff near the bottom of its discharge curve than a worn original. The Blue Charm Metal's modem and display draw current spikes that pull the cell voltage below the BMS cutoff threshold before the OS percentage gauge reaches zero. The fuel gauge IC is still reading state-of-charge from the old cell's stored curve, so the reported percentage and actual cutoff voltage don't match. One complete calibration cycle — full discharge to automatic shutdown, then uninterrupted charge to 100% — corrects the mapping and pushes the shutdown point back toward 5–8%.

USB fast charge not activating on the first cycle after replacement

On first insertion of a new BT50 cell, the charge IC on the Blue Charm Metal may not negotiate the proprietary fast-charge protocol because the BMS hasn't yet completed its initialisation handshake with the phone's PMIC. The phone will charge at standard 5V/1A instead of the higher-current rate. Disconnect the cable, power the phone off and back on fully, then reconnect — this resets the PMIC negotiation sequence. After one standard-rate charge cycle completes, fast charging typically activates on the next plug-in.