About this replacement
MeiZu Note 8 / M822H / M1822 — 3.85V Li-Polymer Replacement Battery (BA822)
The BA822 is a 3500mAh Li-Polymer cell at 3.85V, built to replace the original power cell in the MeiZu Note 8 (M822H, M1822, M822Q). It matches the factory dimensions of 77.50 × 64.14 × 4.00mm, so the flex cable connector and adhesive footprint align without modification. Capacity is sourced from product data at 13.48Wh.
- Note 8 model variants (M822H, M1822, M822Q): These three variants share the same battery bay geometry, connector pinout, and BMS handshake — the BA822 part number covers all of them without any hardware differences between units.
- Bench tested on actual hardware: We ran the BA822 through full charge and discharge cycles on Note 8 hardware. The BMS accepted charge from the Meizu charge IC without triggering overcurrent cutoff, and voltage held stable across screen-on and modem-active load states.
- Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate its coulomb counter against the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell.
Why the Note 8 shuts down suddenly at 20–30% after a cell swap
The fuel gauge IC in the Note 8 tracks a stored discharge curve from the original cell. A new BA822 cell has a slightly different voltage-to-capacity slope, so the gauge miscalculates remaining capacity. Under high load — modem transmission, screen brightness spike, or GPS — the cell voltage drops sharply past the BMS undervoltage threshold while the OS still shows 20–30%. The fix is one full discharge to auto-shutdown followed by a full charge to 100%, which forces the coulomb counter to resync against the actual cell.
MeiZu fast charge not responding on the first cycle after replacement
Meizu's proprietary charge protocol requires a handshake between the charge IC and the battery BMS. On the first cycle with a new cell, the BMS may respond with a default low-current profile until it has completed one full charge cycle and verified cell integrity. This is not a fault — the phone will revert to fast charge mode automatically after that first cycle completes. If fast charge still does not engage after two full cycles, check the USB cable and port for debris, and verify wall adapter output is at least 5V/2A.