BBK VIVO X27 Pro B-G3 Compatible Battery 3.85V 3900mAh

BBK VIVO X27 Pro — 3.85V Li-Polymer Replacement Battery (B-G3)

This is a 3.85V, 3900mAh (15.02Wh) Li-Polymer cell that replaces the original B-G3 battery in the VIVO X27 Pro, VIVO X27 Pro Dual SIM, V1836T, and V1836. It fits the same footprint as the factory cell at 72.95 x 62.42 x 5.00mm. If your X27 Pro no longer holds charge through a typical day, this cell restores capacity to factory spec.

• X27 Pro / V1836 platform fit: The V1836 and V1836T share the same battery bay geometry, connector pinout, and BMS handshake protocol. One SKU covers both variants without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a V1836T unit. The BMS communicated correctly with the system, charge IC accepted the cell without error flags, and the fuel gauge IC tracked state-of-charge through a full cycle.
• First-cycle fast charge hold-off: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate against the new cell's discharge curve before the charge IC pushes high current into an uncalibrated cell. Re-enable fast charging after that first full cycle completes.

Why the X27 Pro reports wrong battery percentage after a cell swap

The VIVO X27 Pro uses a coulomb-counter fuel gauge IC that builds its charge model from learned discharge curves on the original cell. When you fit a new cell, the IC still references that old learned curve, so the percentage shown on screen can be off by 10–20%. The fix is one slow, uninterrupted discharge from 100% to automatic shutdown, followed by a full charge to 100% without interruption. After that cycle, the IC resets its reference points against the new cell's actual curve. Percentage accuracy stabilises within two or three further cycles.

Sudden shutdown at 20–30% on the replacement cell

This happens when the modem, screen, or processor pulls a current spike the cell cannot sustain without its terminal voltage dropping below the BMS cutoff threshold — even though the fuel gauge still shows charge remaining. It is a cell-voltage floor problem, not a capacity problem, and it is most common before the fuel gauge IC has recalibrated. Run the recalibration cycle described above first. If shutdowns continue after two full cycles, check that the connector is fully seated — a partial connection raises contact resistance and worsens voltage sag under load, typically causing cutoff below 3.4V.