Oppo A7x BLP683 Compatible Battery 3.85V 3400mAh

Oppo A7x / PBBM00 — 3.85V Li-Polymer Replacement Battery (BLP683)

This is a 3400mAh 3.85V Li-Polymer battery for the Oppo A7x, A7x Dual SIM, and PBBM00. It replaces OEM part BLP683 directly. Swap it in when the original cell has degraded and the phone can no longer hold a full charge through a normal day of use.

• A7x and PBBM00 cell compatibility: The A7x and its Dual SIM variant share the same physical footprint, connector pinout, and BMS handshake protocol. Any cell meeting the BLP683 spec works across both boards without modification.
• Bench tested on actual hardware: We cycled this cell on an A7x mainboard and confirmed the BMS accepted the handshake, the charge IC reached full termination voltage, and coulomb counter tracking engaged without fault codes through two full cycles.
• First cycle fast charge protocol: On first use after installation, disable VOOC fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate against the new cell's discharge curve before high-current charging pushes into an uncalibrated coulomb counter.

Why the A7x reports wrong battery percentage after a cell swap

The A7x uses a fuel gauge IC that learns a cell's discharge curve over time. When you replace the cell, the IC still references the old curve stored in memory. This makes the percentage readout unreliable — the phone may show 40% when the cell is actually near depletion. One full discharge down to auto-shutoff, followed by an uninterrupted charge to 100%, forces the IC to write a new curve against the replacement cell. After that single calibration cycle, percentage tracking aligns correctly.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage cliff failure, not a capacity problem. When the modem fires or the screen backlight peaks, the cell must sustain voltage under that momentary load. A mismatched or uncalibrated cell can't hold the voltage rail, and the phone shuts down even though the fuel gauge still shows charge remaining. Run the calibration cycle described above first. If shutdowns continue, check that the battery connector is fully seated — a partial connection increases internal resistance and collapses the voltage rail faster under load, typically dropping below the 3.2V cutoff threshold.