MeiZu BA611 M5 Replacement Battery 3.85V 3000mAh

MeiZu M5 / M611 Series — 3.85V Li-Polymer Replacement Battery (BA611)

The BA611 is a 3.85V, 3000mAh (11.55Wh) Li-Polymer cell that fits the MeiZu M5, M5 Dual SIM, M611, and M611A smartphones. It replaces the original battery when the phone can no longer hold a usable charge or fails to power on without being plugged in. Dimensions are 78.44 × 62.74 × 3.38mm — confirm clearance before seating the cell.

• M5 and M611 platform compatibility: The M5 and M611 share the same battery bay geometry and connector pinout. The BA611 cell speaks to the same fuel gauge IC across both variants, so the BMS handshake completes without modification.
• Bench tested on actual hardware: We ran the BA611 through charge and discharge cycles on the M611 platform. The BMS held cutoff correctly at both the low-voltage floor and the 4.35V charge ceiling without thermal events.
• First-cycle fuel gauge recalibration: On first use after installation, disable fast charging and run one full discharge-to-charge cycle. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before any high-current charging session begins.

Sudden shutdown at 20–30% on the BA611 replacement cell

This happens because the fuel gauge IC is still using the discharge curve it learned from the original, degraded cell. When the modem fires up during a call or the display hits peak brightness, current draw spikes and the new cell's voltage drops faster than the IC expects. The system reads that as a fault and shuts down even though the cell still has capacity. One full discharge-to-charge cycle recalibrates the coulomb counter and the shutdowns stop.

Phone will not power on after the BA611 sat in storage

Li-Polymer cells self-discharge in storage. If the BA611 dropped below approximately 2.5V per cell, the BMS enters lockout mode to prevent damage and the phone will not respond to the power button. Connect to a charger and leave it for 15–20 minutes without attempting to boot — the charge IC needs to trickle current into the cell until it clears the BMS lockout threshold before normal charging resumes. If voltage has recovered above 3.0V, the phone will power on normally.