Vivo S12 Pro B-T3 Compatible Battery 3.87V 4050mAh

Vivo S12 Pro — 3.87V Li-Polymer Replacement Battery (B-T3)

This is a 3.87V, 4050mAh (15.67Wh) Li-Polymer replacement battery for the Vivo S12 Pro, S12 Pro 5G, S12 Pro 5G 2022 Standard Edition, and V2163A. It replaces the original B-T3 cell when the existing battery shows capacity fade, unexpected shutdowns, or swelling. The dimensions are 83.75 x 61.45 x 4.50mm — confirm your device variant before installation.

• S12 Pro and V2163A compatibility: These models share the same B-T3 cell format, connector pinout, and BMS handshake protocol. The fuel gauge IC on all variants reads the same cell ID — swapping in this cell triggers no lock-out or charge refusal on the main board.
• Bench tested on actual hardware: We ran this cell through full charge cycles and monitored BMS communication, charge IC response, and cutoff voltage. The cell held 3.87V nominal across load cycles and the BMS reported state-of-charge correctly after a full recalibration pass.
• First cycle after installation: Disable fast charging for one complete discharge-charge cycle. The fuel gauge IC is calibrated to the old cell's discharge curve. Running one slow cycle first lets the coulomb counter reset against the new cell before high-current charging starts.

Sudden shutdown at 20–30% on the S12 Pro after a cell swap

This happens because the fuel gauge IC still holds the discharge curve of the degraded original cell. The new cell has a steeper voltage cliff at low charge states — the phone reads 25% but the cell voltage drops below the modem and display load threshold and the BMS trips. The OS sees a hard cutoff and logs it as a crash. One full discharge to automatic shutdown followed by an uninterrupted charge to 100% resets the coulomb counter and clears the mismatch.

USB-PD fast charge not activating on the first cycle after replacement

On the first charge after installation, the charge IC may not receive a valid handshake from the new BMS and falls back to standard 5V charging. This is normal — the BMS on a fresh cell needs one complete cycle before it signals the charge IC to negotiate fast-charge protocols. Plug in with the stock charger, let the first charge complete without interruption, and fast charging will activate automatically on the second cycle. Do not use a third-party charger for this first cycle.