About this replacement
MeiZu Pro 7 Plus / M793Q — 3.85V Li-Polymer Replacement Battery (BA793)
This is a 3400mAh 3.85V Li-Polymer cell for the MeiZu Pro 7 Plus (M793Q). It replaces the original BA793 battery when capacity has dropped after repeated charge cycles. It powers the display, processor, modem, and all onboard functions.
- Pro 7 Plus and M793Q fitment: Both model designations refer to the same hardware platform. They share the same battery bay dimensions, the same 3.85V nominal rail, and the same BMS connector pinout. One cell covers both.
- Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the Pro 7 Plus board. The BMS handshake completed correctly, charge current stepped down at the expected 4.35V cutoff, and the fuel gauge IC accepted the new cell without throwing an error flag.
- Fuel gauge recalibration on first cycle: After installing this battery, disable fast charging and run one complete discharge down to automatic shutdown, then charge to 100% on standard current. This gives the fuel gauge IC a clean reference discharge curve for the new cell before fast charge pushes high current into an uncalibrated state.
Sudden shutdown at 20–30% on the Pro 7 Plus after a cell swap
This happens because the fuel gauge IC is still using the discharge curve it mapped to the old, degraded cell. The new cell has a steeper voltage cliff at the low end than the worn cell did, so the phone hits the hardware undervoltage cutoff while the OS still shows charge remaining. The fix is one full unconstrained discharge-charge cycle with fast charging off. After that cycle, the coulomb counter has a fresh baseline and the reported percentage tracks actual cell voltage correctly.
USB fast charge not activating on the first cycle after replacement
On the first connection after a cell swap, the charge IC may default to trickle or standard 5V charging rather than negotiating the higher voltage profile. This is a protective handshake behaviour — the charge IC checks BMS state before committing to fast charge current. Plug in with the screen on and allow the first charge to complete fully at whatever rate the phone accepts. On the second connection, fast charge typically re-engages. If it does not, clear the battery stats in recovery and reboot to trigger a fresh BMS negotiation.