Vivo S6 5G B-M7 Compatible Battery 3.87V 4350mAh

Vivo S6 5G / G1 5G — 3.87V Li-Polymer Replacement Battery (B-M7)

The B-M7 is a 3.87V, 4350mAh Li-Polymer cell that powers the Vivo S6 5G and G1 5G (V1962, V1962A). It slots into the same battery bay as the original and connects to the same fuel gauge IC and charge controller. Capacity figures come from the product data — 16.83Wh at nominal voltage.

• S6 5G / G1 5G platform fit: These models share the same mainboard layout, connector pinout, and BMS handshake protocol. One cell covers the full variant range listed — V1962 and V1962A included.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on S6 5G hardware. The BMS accepted the cell without fault codes, and the charge IC transitioned through trickle, CC, and CV phases cleanly.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one full discharge-to-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging begins on an uncalibrated cell.

Sudden shutdown at 20–30% on the S6 5G after a cell swap

A new Li-Polymer cell has a steeper voltage cliff than a worn cell the fuel gauge IC was originally trained on. When the S6 5G pulls high current — 5G modem switching, screen-on bursts — the cell voltage dips below the BMS cutoff threshold even though the reported percentage is still 20–30%. The phone interprets this as a hard low-voltage event and shuts down. One full slow-charge cycle after replacement retrains the coulomb counter and aligns the percentage display with the actual cell discharge curve.

USB fast charge not activating on the first cycle after replacement

Vivo's proprietary fast charge protocol requires a BMS handshake before the charge IC raises current above the standard 5V/1A baseline. On the first cycle with a new cell, the BMS may not complete that handshake until the cell has been charged once at standard rate. If fast charge fails to activate, complete one full standard charge, allow the phone to boot fully, then reconnect the original charger. Fast charge should negotiate correctly on the second cycle.