Vivo IQOO Neo5S B-S9 Replacement Battery 7.74V 2200mAh

Vivo IQOO Neo5S — 7.74V Li-Polymer Replacement Battery (B-S9)

This is a 7.74V, 2200mAh Li-Polymer replacement battery for the Vivo IQOO Neo5S smartphone. It carries OEM part number B-S9 and slots into the Neo5S chassis to restore power to the processor, display, and wireless radios. Use the product data capacity figure — 2200mAh / 17.03Wh — as the reference spec.

• IQOO Neo5S fit: The Neo5S uses a dual-cell Li-Polymer configuration at a nominal 7.74V rail. The B-S9 matches that voltage, connector pinout, and BMS handshake — the phone's charge IC will recognise the cell and accept charge negotiation without triggering a hardware fault.
• Bench tested on actual hardware: We cycled this battery through charge and discharge on the Neo5S board. The BMS held the 4.45V per-cell ceiling correctly, cutoff engaged cleanly at the low-voltage threshold, and the charge IC completed a full cycle without error flags in the system log.
• First-cycle fast-charge calibration: 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 fast charging pushes current into an uncalibrated cell.

Why the IQOO Neo5S reports wrong battery percentage after a cell swap

The fuel gauge IC on the Neo5S learns a cell's discharge curve over time and stores that data in firmware. When you fit a new cell, the IC is still referencing the old degraded curve, so percentage readings can sit 10–20% off actual state of charge. One full standard charge-discharge cycle forces the coulomb counter to recalibrate against the new cell's actual voltage slope. After that cycle, percentage accuracy typically stabilises within two to three further charges.

Sudden shutdown at 20–30% remaining on the replacement cell

This happens when the fuel gauge IC has not yet mapped the new cell's voltage cliff — the point where cell voltage drops sharply under modem or display load. The phone's protection circuit reads that voltage drop as a low-cell event and cuts power before the displayed percentage reaches zero. Run one full discharge down to automatic shutdown, then charge uninterrupted to 100% at standard current. That single cycle gives the coulomb counter enough data to place the low-voltage cutoff at the correct percentage.