MeiZu M6T Replacement Battery BA811 3.85V 3200mAh

MeiZu M6T / M811 Series — 3.85V Li-Polymer Replacement Battery (BA811)

The BA811 is a 3.85V, 3200mAh lithium-polymer cell that fits the MeiZu M6T, M811, M811T, and M811H. It restores power to phones where the original cell no longer holds a working charge. Capacity figures come from the product data: 3200mAh / 12.32Wh.

• M811-series platform fit: The M6T, M811, M811T, and M811H share the same mainboard voltage rail and connector pinout. The BA811 part number covers all variants because the BMS handshake and charge termination voltage are identical across that board revision.
• Bench tested on actual hardware: We ran the BA811 through charge and discharge cycles on M811-series hardware. The BMS accepted the standard 4.35V charge termination without tripping, and protection circuits responded correctly to simulated short and over-discharge conditions.
• Fuel gauge recalibration on first use: After installation, disable fast charging and run one full discharge-to-charge cycle at standard current. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging pushes current into an uncalibrated state.

Sudden shutdown at 20–30% on the BA811 replacement cell

A fresh lithium-polymer cell has a steeper voltage cliff than a worn original. When the modem fires up for a call or the screen peaks at full brightness, instantaneous current draw can pull the cell voltage below the BMS cutoff threshold — even when the gauge still reads 25%. The fuel gauge IC inherited the old cell's discharge curve, so the reported percentage does not reflect the new cell's actual state of charge at that load point. One full discharge cycle — taken below 10% before recharging — forces the coulomb counter to resync to the BA811's real capacity. After that cycle, shutdowns at mid-charge typically stop.

USB fast charge not working after battery replacement

MeiZu's proprietary fast-charge protocol negotiates between the charger and the phone's charge IC at the start of each session. On the first cycle after a cell swap, the charge IC may default to standard 5V/1A input rather than accept the elevated voltage or current of the fast-charge profile. This happens because the BMS reports an unfamiliar cell state on the first handshake. Charge the phone once at standard speed with the original MeiZu cable and charger, then disconnect and reconnect — fast charging typically resumes from the second session onward once the IC has logged a complete baseline cycle.