About this replacement
MeiZu Pro 7 / M792Q / M792C — 3.85V Li-Polymer Replacement Battery (BA792 / BA791)
This 3.85V, 2900mAh Li-Polymer cell is a direct replacement for the MeiZu Pro 7 (M792Q, M792C). It fits the internal battery bay and connects to the same flex ribbon as the original BA792 and BA791 units. If the Pro 7 is shutting down early, charging slowly, or not holding charge between uses, the original cell has likely degraded past useful capacity.
- Pro 7 M792Q and M792C compatibility: Both variants use the same 98.46 × 39.40 × 4.20mm footprint, identical connector tab placement, and share the same voltage rail. One cell covers both SKUs — no BMS handshake differences between them.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on a Pro 7 mainboard. The BMS accepted the cell without fault codes, and the charge IC stepped through trickle, CC, and CV phases as expected on a healthy cell.
- Fuel gauge recalibration on first cycle: After installation, disable fast charging and run one full discharge-to-charge cycle before resuming normal use. The Pro 7's fuel gauge IC is calibrated to the old cell's discharge curve — skipping this step with fast charging active pushes current into an uncalibrated cell and leaves the percentage readout inaccurate for weeks.
Sudden shutdown at 20–30% on the replacement cell
This is a voltage cliff problem, not a capacity problem. Under modem or display load, the cell's internal resistance causes a voltage drop that crosses the BMS cutoff threshold — even though the fuel gauge still shows charge remaining. The fuel gauge IC hasn't yet mapped the new cell's discharge curve, so it reads percentage optimistically. Run two full discharge-charge cycles without fast charging to let the coulomb counter recalibrate, and the shutdowns will stop.
USB fast charging not working on the first cycle after replacement
On the first charge after a cell swap, the Pro 7's charge IC defaults to a trickle or standard rate while it verifies cell impedance on the new unit. This is normal — the handshake between the charge controller and BMS requires at least one complete cycle before the fast charge protocol re-enables. Plug in with the standard charger, let the first charge complete to 100%, and fast charging will resume on the next session. Do not interrupt that first cycle.