About this replacement
Vivo S16 / V2244A — 3.89V Li-Polymer Replacement Battery (B-X6)
This is a 3.89V, 4500mAh (17.51Wh) lithium-polymer replacement battery for the Vivo S16 and V2244A smartphones. It replaces OEM part number B-X6 and fits the same physical cavity and connector as the original cell. Capacity figures come from our product data, not estimates.
- S16 and V2244A compatibility: Both the S16 and V2244A share the same mainboard platform, battery connector pinout, and BMS handshake protocol — that is why one cell covers both model numbers. Swapping between them does not change anything electrically.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the S16 platform. The BMS accepted the cell without throwing a protection fault, and the charge IC communicated normally with the fuel gauge through the full cycle.
- 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 fast charging pushes current into an uncalibrated state — skipping this step causes erratic percentage readings early on.
Sudden shutdown at 20–30% on a replacement cell in the S16
This happens because the fuel gauge IC is still calibrated to the old cell's voltage-discharge curve. When the new cell hits a voltage cliff — often around 3.5V under modem or display load — the phone cuts power before the gauge reaches 0%. The fix is one full uninterrupted discharge to shutdown followed by a full charge, which forces the coulomb counter to reset its endpoints against the new cell. After that cycle, low-percentage shutdowns typically stop.
USB fast charge not activating on the first cycle after installation
After a cell swap, the charge IC on the S16 can refuse to negotiate fast-charge protocols — including Vivo's FlashCharge — on the first charge cycle. This is a BMS initialisation behaviour: the IC defaults to standard 5V/1A until it has completed one full cycle and confirmed the cell is within expected impedance range. Plug in via a standard charger for the first full charge, let it reach 100%, then switch back to your fast charger. Fast-charge rates restore after that initial cycle.