Vivo V15 Pro B-G1 Compatible Battery 3.85V 3700mAh

Vivo V15 Pro / 1818 — 3.85V Li-Polymer Replacement Battery (B-G1)

This is a 3700mAh (14.25Wh) Li-Polymer cell for the Vivo V15 Pro (model 1818). It replaces the original B-G1 battery when capacity has dropped, the phone shuts down unexpectedly, or the original cell no longer holds a usable charge. Voltage is 3.85V nominal — match this before fitting any cell to this board.

• V15 Pro and 1818 compatibility: Both model identifiers reference the same hardware revision. The battery connector, BMS handshake, and charge IC are identical across V15 Pro units sold under either number. One cell fits both.
• Bench tested on actual hardware: We cycled this cell through charge, full discharge, and a second charge sequence on a V15 Pro unit. The BMS accepted the cell without error flags, and the charge IC ramped normally through CC and CV phases.
• First-cycle fast charge protocol: On first use after installation, disable fast charging and run one complete discharge-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging pushes current into an uncalibrated state.

Sudden shutdown at 20–30% on a new B-G1 cell

A freshly fitted cell can trigger abrupt shutdowns while the percentage indicator still reads 20–30%. This happens because the fuel gauge IC is still calibrated to the old cell's discharge curve. When the new cell's actual voltage drops under screen or modem load, it hits the hardware cutoff before the gauge catches up. Running two full discharge-charge cycles at standard rate resolves this — the coulomb counter resets to the new cell's parameters after those cycles complete.

USB fast charge not activating after cell replacement

After a B-G1 swap, some V15 Pro units charge at standard rate only, even with a fast-charge adapter connected. The charge IC on this board performs a handshake with the BMS on first cycle — if the cell voltage is low from storage, the IC defaults to a conservative charge rate until it confirms cell health. Charge the phone fully once at standard rate. On the second charge session, fast charging typically re-engages as the IC accepts the new cell's impedance profile.