Apple A3081 iPhone Replacement Battery 3.8V 3500mAh

Apple A3081 / A3286 / A3287 / A3288 — 3.8V Li-Polymer Replacement Battery (NA264)

This is a 3.8V, 3500mAh (13.3Wh) lithium-polymer cell for the Apple iPhone models A3081, A3286, A3287, and A3288. It replaces the original cell when capacity has degraded and the device can no longer hold a usable charge. Voltage and capacity match OEM specification per part number NA264.

• A3081 / A3286 / A3287 / A3288 platform fit: These four models share the same battery bay dimensions, flex connector pinout, and BMS handshake protocol — all four accept the NA264 cell without modification to the battery connector or housing.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a test unit. The BMS accepted charge from both 5W and USB-PD fast charge inputs, communicated cell state to the fuel gauge IC, and held voltage flat across the mid-range discharge window without premature cutoff.
• Fuel gauge recalibration after installation: On first use after swapping this cell, disable fast charging and run one complete discharge-to-charge cycle at standard rate. This lets the fuel gauge IC build an accurate discharge curve map against the new cell before high-current charging pushes current into an uncalibrated state.

Sudden shutdown at 20–30% on the replacement cell

A new cell with an uncalibrated fuel gauge IC will often trigger an abrupt shutdown well above 0% — typically between 20% and 30%. The device's coulomb counter is still referencing the discharge curve from the old, degraded cell. Under modem or display load, the new cell's actual voltage momentarily dips below the threshold the IC expects at that percentage, and the device cuts power to protect the circuit. One full slow discharge-charge cycle forces the IC to relearn the new cell's voltage-to-capacity relationship. After that cycle, the shutdown floor returns to below 5%.

USB-PD fast charge not accepted on first cycle after replacement

After installation, some units will only accept 5W standard charge on the first session and refuse fast charge negotiation. The charge IC treats a new cell with unknown internal resistance as a precaution — it defaults to trickle or standard current until it has profiled the cell once. This is not a fault with the battery or the charger. Plug in at 5W, allow a full charge to 100%, and fast charging will be accepted on subsequent sessions without any further intervention.