Vivo Y93 B-F3 Replacement Battery 3.85V 3900mAh

Vivo Y93 / Y93s Series — 3.85V Li-Polymer Replacement Battery (B-F3)

This is a 3.85V, 3900mAh (15.02Wh) Li-Polymer cell that replaces the original B-F3 battery in the Vivo Y93, Y93s, Y93st, and V1818CA. It restores full phone function — calls, apps, camera, and screen — when the original cell has degraded past usable capacity. Dimensions are 88.50 × 62.50 × 4.16mm, matching the original cell footprint exactly.

• Y93 series fit: The Y93, Y93s, Y93st, and V1818CA all share the same B-F3 cell specification — same voltage rail, same physical envelope, and the same BMS connector pinout. One part number covers the full model range.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on Y93 hardware. The BMS handshake completed correctly, the charge IC accepted the cell without fault codes, and the fuel gauge IC began tracking state-of-charge within the first full cycle.
• First-cycle fast charge tip: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle at standard rate. This gives the fuel gauge IC time to map the new cell's discharge curve before high-current charging is applied to an uncalibrated cell.

Why the Y93 reports wrong battery percentage after a cell swap

The Y93 uses a fuel gauge IC that tracks battery state based on a stored discharge curve built up from the old cell. When a new cell goes in, that stored curve no longer matches the actual cell chemistry, so the reported percentage drifts — sometimes by 10–20%. The fix is one full calibration cycle: discharge the phone until it shuts off automatically, then charge uninterrupted to 100% without fast charging enabled. After that cycle, the fuel gauge IC recalibrates its coulomb counter against the new cell and percentage readings stabilise.

Sudden shutdown at 20–30% on the replacement cell

This happens when the cell voltage drops sharply under high load — modem activity, screen at full brightness, or GPS — before the fuel gauge IC reads 0%. The original cell's internal resistance rises with age, so the phone's shutdown threshold was calibrated to a degraded voltage curve. A new cell has lower internal resistance but the fuel gauge IC hasn't learned its curve yet, causing a mismatch at the voltage cliff around 3.5–3.6V. Run the calibration cycle described above; after one full discharge-charge cycle the IC maps the new cell's floor correctly and premature shutdowns stop.