Apple iPhone 8 Plus Replacement Battery 616-00367 3.82V 3300mAh

Apple iPhone 8 Plus — 3.82V Li-Polymer Replacement Battery (616-00367)

This 3.82V, 3300mAh lithium-polymer cell is a direct replacement for the Apple iPhone 8 Plus, covering model variants A1864, MQ8F2LL/A, and iPhone 8+ designations. It matches the OEM part number 616-00367 and fits the original battery bay without modification. Capacity and voltage are pulled from product data, not estimated.

• iPhone 8 Plus and A1864 platform fit: These models share the same battery bay dimensions, connector pinout, and BMS handshake protocol. The 109.60 × 49.70 × 3.68mm cell envelope matches the OEM footprint precisely, and the flex connector carries the same authentication and temperature sense lines the iPhone 8 Plus logic board expects.
• Bench tested on actual hardware: We cycled this cell on an iPhone 8 Plus logic board and confirmed the BMS completed charge termination cleanly at 4.35V, with no false cutoff during the modem transmit spikes that commonly trip underspec cells.
• Fuel gauge recalibration on first cycle: On first use after installation, disable fast charging and run one full discharge down to auto-shutdown, then charge to 100% on a standard 5W adapter. This gives the fuel gauge IC one complete reference cycle against the new cell's discharge curve before high-current charging begins.

Sudden shutdown at 20–30% on the iPhone 8 Plus after a cell swap

This happens when the fuel gauge IC is still calibrated to the old cell's internal resistance curve. The replacement cell has lower impedance, so the coulomb counter miscalculates remaining capacity and triggers a protective shutdown before the cell is actually depleted. The modem and display create a combined load spike that drives cell voltage below the shutdown threshold for a split second — enough to cut power. Run one full discharge-to-shutdown cycle without fast charging, then a full charge, and the gauge IC will remap to the new cell's curve.

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

The iPhone 8 Plus charge IC negotiates fast charge only after it reads valid temperature and authentication data from the battery's flex connector. On a new cell, the BMS may not pass authentication on the first connection attempt, causing the phone to fall back to 5W standard charging. Disconnect the battery flex, reseat it firmly, and power on again — the charge IC renegotiates the handshake. If fast charge still does not engage, complete one full standard-charge cycle first; the BMS initialises fully after the first complete charge termination at 4.35V.