About this replacement
Apple iPhone 13 Pro — 3.85V Li-Polymer Replacement Battery (A2656)
This 3.85V, 3000mAh (11.55Wh) Li-Polymer cell is a direct replacement for the Apple iPhone 13 Pro (A2656). It fits the iPhone 13 Pro and iPhone 13 Pro 5G (A2640). Install it when the original cell has degraded past the point where iOS Battery Health flags service needed.
- iPhone 13 Pro and 13 Pro 5G fit: Both variants share the same battery bay geometry, connector pinout, and BMS handshake protocol — the A2656 part number covers both. No adapter or modification required at the connector.
- Bench tested on actual hardware: We cycled this cell through full charge and discharge on an iPhone 13 Pro unit. The BMS accepted the cell without error flags, and the charge IC stepped through trickle, CC, and CV phases correctly to termination.
- Fuel gauge recalibration on first install: Disable fast charging for the first complete discharge-charge cycle after installation. This allows the coulomb counter to map the new cell's discharge curve before high-current USB-PD charging begins. Skipping this step causes the percentage readout to drift for the first several cycles.
Why the iPhone 13 Pro reports wrong battery percentage after a cell swap
The fuel gauge IC on the iPhone 13 Pro uses a coulomb counter calibrated to the original cell's charge curve. When a new cell goes in, that curve no longer matches what the IC expects. The gauge reads voltage-based estimates until a full cycle teaches it the new cell's actual discharge profile. One complete discharge to automatic shutdown followed by an uninterrupted charge to 100% resets the learning algorithm and brings percentage accuracy back in line.
Sudden shutdown at 20–30% on the replacement cell
This happens when the replacement cell cannot sustain voltage under high-current loads — typically the 5G modem or ProMotion display ramping together. The cell voltage drops below the BMS cutoff threshold even though the fuel gauge still shows charge remaining. It is not a defective cell — it is an uncalibrated gauge hitting a real voltage cliff. Run one full discharge cycle without fast charge, and confirm the shutdown threshold moves below 15% before routine use.