About this replacement
Apple iPhone 15 Pro Max — 3.8V Li-Polymer Replacement Battery (NA247)
This 3.8V, 4650mAh (17.67Wh) Li-Polymer cell replaces the original battery in the iPhone 15 Pro Max. It fits models A3082, A3289, A3290, and A3291. Install it when your original cell has degraded below usable battery health, or when the phone shuts down unexpectedly under load.
- iPhone 15 Pro Max model variants: The A3082, A3289, A3290, and A3291 model numbers reflect regional hardware variants of the same iPhone 15 Pro Max chassis. They share the same battery bay dimensions, connector pinout, and BMS handshake protocol — this cell fits all of them.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the iPhone 15 Pro Max platform. The BMS accepted the cell without rejection flags, charge current stepped correctly through trickle, CC, and CV phases, and the coulomb counter initialised on the first full cycle.
- First-cycle fuel gauge reset: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle at standard speed. This lets the fuel gauge IC map the new cell's discharge curve before iOS locks in its capacity estimate — skipping this step is the main cause of erratic percentage readings post-swap.
Sudden shutdown at 20–30% on the iPhone 15 Pro Max after a battery swap
The iPhone 15 Pro Max pulls hard current spikes from the cell during 5G modem bursts and ProMotion display peaks. If the fuel gauge IC hasn't completed a full calibration cycle, iOS's voltage model is still mapped to the old cell's internal resistance curve. The new cell hits a voltage cliff the software didn't predict, and the phone shuts down to protect the SoC — even though charge remains. Run one full discharge to approximately 1–2% followed by a full charge at standard wattage. After that cycle, iOS recalibrates and the shutdowns stop.
USB-PD fast charging not engaging on the first cycle after replacement
After a cell swap, the charge IC on the iPhone 15 Pro Max starts the new cell in trickle mode regardless of what the charger offers. The BMS needs to confirm cell voltage is above the fast-charge entry threshold — typically 3.0V — before it signals the USB-PD controller to step up wattage. If the replacement cell shipped at low state of charge, this trickle phase can last longer than expected. Plug in, leave it connected, and fast charging will engage automatically once the cell clears the threshold; no reset or adapter change is needed.