About this replacement
Vivo iQOO Neo6 SE 5G — 7.74V Li-Polymer Replacement Battery (B-U6)
This is a 7.74V, 2250mAh (17.42Wh) lithium-polymer battery for the Vivo iQOO Neo6 SE 5G (model V2199A). It replaces part number B-U6 when the original cell has degraded and no longer holds adequate charge. Physical dimensions are 86.80 × 63.50 × 5.10mm — confirm clearance before installation.
- iQOO Neo6 SE 5G / V2199A fit: Both model references share the same battery bay geometry, connector pinout, and BMS handshake protocol — the B-U6 cell serves both without modification.
- Bench tested on actual hardware: We cycled this cell through charge and full discharge on the iQOO Neo6 SE 5G platform. The BMS accepted the cell without flagging an incompatibility error, and the charge IC engaged correctly at startup.
- First-cycle fast-charge hold: After installation, disable fast charging for one complete discharge-charge cycle. The fuel gauge IC is calibrated to the old cell's discharge curve — running a full slow cycle first lets the coulomb counter recalibrate against the new cell before high-current charging begins.
Why the iQOO Neo6 SE 5G reports wrong battery percentage after a cell swap
The fuel gauge IC stores a learned discharge curve from the original cell. When a new cell goes in, that stored curve no longer matches the actual voltage-to-capacity relationship of the replacement. The phone reads voltage and maps it against the old curve, so percentages drift — often showing 100% too quickly or dropping sharply near 30%. One full slow discharge to 0% followed by an uninterrupted charge to 100% resets the coulomb counter and corrects the reported values.
Sudden shutdown at 20–30% on the replacement cell
This happens when the modem or display draws a current spike the cell cannot sustain without dropping below the BMS cutoff threshold — typically around 3.0V per cell. A freshly installed cell with an uncalibrated fuel gauge makes this worse, because the displayed percentage doesn't reflect actual remaining capacity. Run two full slow discharge-charge cycles to let the gauge re-anchor its low-voltage endpoint. If shutdowns persist past that, check that the battery connector is fully seated — a high-resistance contact causes voltage drop under load at the same 20–30% range.