Vivo Y32 B-T7 Compatible Battery 3.87V 4900mAh

Vivo Y32 / Y21e Series — 3.87V Li-Polymer Replacement Battery (B-T7)

This is a 3.87V, 4900mAh lithium-polymer battery with OEM part number B-T7. It fits the Vivo Y32, Y32 2021 4G, V2158, Y21e, and two additional compatible models. It replaces the internal cell when the original has degraded, fails to hold charge, or causes unexpected shutdowns.

• Y32 and Y21e series compatibility: These models share the same battery bay geometry, connector pinout, and BMS handshake protocol — all anchored to the B-T7 specification. Swapping between them requires no wiring or adapter changes.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Y32 platform. The BMS accepted the cell, reported state-of-charge correctly after one full cycle, and triggered no protection cutoffs during normal load transitions.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-charge cycle at standard current. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging begins on an uncalibrated cell.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage cliff, not a calibration glitch. A fresh cell with a different internal resistance profile can drop below the SoC cutoff threshold under modem or display load even when the fuel gauge still shows charge remaining. The phone's protection IC sees the voltage sag as a low-cell event and cuts out. One full discharge-to-shutdown followed by a complete charge resets the coulomb counter and typically eliminates this behaviour.

USB-PD fast charge not accepted on the first cycle after swap

Vivo's proprietary charge protocol negotiates current limits through the BMS on the first handshake after a new cell is installed. Until that first cycle completes, the charge IC may default to standard 5V/1A input rather than accepting higher-rate charging. This is not a fault in the cell. Run one full charge at standard current, then reconnect the fast charger — the handshake succeeds once the BMS has logged an initial charge event against the new cell.