Vivo B-M1 V17 Replacement Battery 3.87V 4300mAh

Vivo V17 / V19 Series — 3.87V Li-Polymer Replacement Battery (B-M1)

This is a 3.87V, 4300mAh Li-Polymer replacement battery for the Vivo V17, V19, V19 Neo, and PD1948 smartphones. It uses OEM part number B-M1 and matches the original cell's voltage, capacity, and physical dimensions at 78.60 × 62.20 × 5.20mm. Install it when the original cell no longer holds charge through a normal day of use.

• V17, V19, V19 Neo, and PD1948 compatibility: These four models share the same battery bay geometry, connector pinout, and BMS handshake protocol. The B-M1 cell fits all four without modification to the flex cable or adhesive retention points.
• Bench tested on actual hardware: We cycled this cell on a V19 Neo unit and confirmed the BMS accepted the cell on first insertion, reported state of charge correctly, and passed USB charge negotiation without error flags in the system log.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging begins pushing into an uncalibrated coulomb counter.

Sudden shutdown at 20–30% on the replacement cell

A new B-M1 cell can trigger sudden shutdowns between 20–30% if the fuel gauge IC is still calibrated to the old, degraded cell's discharge curve. The old cell had a steeper voltage drop at low charge — the gauge learned that curve. The new cell holds voltage longer, but the gauge still cuts power at the same voltage threshold it associated with "empty" on the old cell. Run one full discharge to under 5% and a complete charge to 100% without fast charging — this resets the coulomb counter baseline and eliminates the premature cutoff.

USB fast charge not working after battery replacement

Vivo's proprietary fast charge protocol requires the charge IC to negotiate with the battery BMS before ramping current. On the first cycle after a cell swap, the BMS may not complete this handshake, so the phone falls back to standard 5V charging. This is not a fault with the cell — it is a one-cycle initialisation behaviour. Complete one full standard charge to 100%, then reconnect the original fast charger and the protocol negotiation will complete normally at approximately 9V input.