Huawei Ascend P8 Max Replacement Battery HB3665D2EBC 3.8V

Huawei Ascend P8 Max — 3.8V Li-Polymer Replacement Battery (HB3665D2EBC)

This is a 3.8V, 4360mAh Li-Polymer cell that replaces the original HB3665D2EBC battery in the Huawei Ascend P8 Max. It fits the DAV-703L and DAV-713L variants as well. Same dimensions at 130.50 × 63.52 × 3.25 mm, same connector pinout, same BMS handshake the charge IC expects.

• P8 Max DAV-703L and DAV-713L compatibility: Both variants share the same battery bay dimensions, connector layout, and charge IC protocol. One cell covers the entire P8 Max line without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the P8 Max platform. The BMS handshake completed on first connection, and the charge IC accepted the cell without triggering protection flags.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one full discharge-charge cycle at standard rate. This lets the fuel gauge IC map its coulomb counter against the new cell's discharge curve before high-current charging begins.

Sudden shutdown at 20–30% on the P8 Max after a cell swap

The P8 Max fuel gauge IC stores a discharge curve calibrated to the original cell. When a new cell goes in, that stored curve no longer matches the actual voltage-versus-capacity relationship of the replacement. The phone reads 25% remaining, but the real open-circuit voltage has already dropped below the modem's minimum rail — so the device shuts off. Running one full unconditioned discharge-charge cycle forces the coulomb counter to relearn the new cell's cliff point. After that cycle, the reported percentage tracks actual capacity correctly.

Device not powering on after the replacement cell sat in storage

Li-Polymer cells self-discharge in storage. If the replacement cell drops below 2.5V per cell during shipping or shelf time, the BMS enters lockout mode and blocks current flow entirely — the phone shows nothing when you press power. Connect the phone to a wall charger and leave it for 20–30 minutes without pressing any buttons. The charge IC trickle-charges the cell back above the BMS recovery threshold, typically around 2.9V, at which point the BMS releases the lockout and normal charging resumes.