Apple iPhone SE 2 Replacement Battery 3.82V 1850mAh

Apple iPhone SE 2 — 3.82V Li-Polymer Replacement Battery (A2312)

This 3.82V, 1850mAh Li-Polymer battery fits the Apple iPhone SE 2nd generation. It replaces part number A2312 when the original cell has degraded and can no longer hold a usable charge. Dimensions are 94.00 × 38.60 × 3.50mm — a direct physical match for the SE 2 housing.

• iPhone SE 2 (A2312) cell match: The SE 2 uses the same A2312 cell across all regional variants. Voltage rail, connector pinout, and BMS handshake requirements are identical across that model run, so one part number covers the full range.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on an SE 2 unit. The BMS accepted charge from both standard 5W and 12W adapters without tripping protection or throwing a charge fault in iOS diagnostics.
• Fuel gauge recalibration on first use: After installation, disable fast charging and run one complete discharge-to-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging begins — skipping this step is the leading cause of erratic percentage readings post-swap.

Sudden shutdown at 20–30% on the replacement cell

The SE 2 fuel gauge IC holds a learned discharge curve from the old cell. A fresh A2312 cell has a steeper voltage cliff under modem and display load than a worn cell — the IC doesn't know that yet. When the new cell voltage dips briefly under load, iOS interprets it as critically low and shuts down, even though the reported percentage still reads 20–30%. One full discharge-charge cycle at standard rate forces the coulomb counter to recalibrate against the new curve. After that cycle, shutdowns at false percentages stop.

Why the iPhone SE 2 reports wrong battery percentage after a cell swap

iOS calibrates battery percentage using a stored discharge model built from the previous cell's behaviour over hundreds of cycles. Swapping in a new A2312 cell means the stored model no longer matches the actual cell chemistry. The result is percentage readings that jump, stall, or drop suddenly — especially between 40% and 15%. Run the phone down to auto-shutdown from a full charge, then charge uninterrupted to 100% without fast charging enabled. That single cycle resets the fuel gauge IC's reference points against the new cell.