About this replacement
Apple iPhone 11 — 3.83V Li-Polymer Replacement Battery (616-00641)
This 3.83V Li-Polymer battery delivers 3100mAh (11.87Wh) of capacity for the iPhone 11, covering model variants A2111 and A2221. It replaces the original 616-00641 cell when capacity has degraded through normal chemical aging. Fit is direct — same dimensions at 100.90 × 44.60 × 4.40mm and the same connector layout as the OEM unit.
- A2111 and A2221 coverage: Both variants run the same power architecture, voltage rail, and BMS handshake protocol, so one cell covers the full iPhone 11 lineup regardless of regional SKU differences.
- Bench tested on actual hardware: We cycled this cell on an iPhone 11 mainboard and confirmed the BMS handshake completed correctly, charge IC accepted the cell without flagging a service warning, and capacity reporting settled within the first full cycle.
- First-cycle fuel gauge calibration: After installation, disable fast charging and complete one full discharge-to-charge cycle at standard 5W. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell.
Why the iPhone 11 reports wrong battery percentage after a cell swap
The iPhone 11 uses a coulomb counter and fuel gauge IC that calibrates its percentage model against the previous cell's discharge curve. When a new cell goes in, that curve no longer matches the stored data. The result is percentage readings that jump, stall, or report full charge well before the cell is actually topped up. One complete discharge-to-zero followed by an uninterrupted charge to 100% resets the calibration baseline and brings percentage reporting back into line.
Sudden shutdown at 20–30% on the replacement cell
This happens when the fuel gauge IC still holds calibration data from the old, degraded cell. Under high-draw conditions — modem activity, GPS, or screen-on workloads — the new cell's voltage drops briefly below the hardware cutoff threshold even though the displayed percentage suggests capacity remains. The phone reads this as a voltage cliff and shuts down as a protection measure. Run one full discharge cycle without fast charging to let the coulomb counter recalibrate against the actual cell chemistry, then verify the shutdown no longer occurs below 3.50V on the next discharge.