BL263 ZUK Z2 Pro Compatible Battery 3.85V 3100mAh

ZUK Z2 Pro Series — 3.85V Li-Polymer Replacement Battery (BL263)

The BL263 is a 3.85V, 3100mAh Li-Polymer cell that fits the ZUK Z2 Pro, Z2 Pro Ultimate Edition, Z2 Pro Ultimate Edition TD-LTE Dual SIM, and Z2 Pro Exclusive Edition. It restores power to the phone for calls, messaging, apps, and media playback. Swap it when the original cell no longer holds enough charge to carry the phone through a normal day.

• Z2 Pro platform compatibility: Every variant in the Z2 Pro line — including the TD-LTE Dual SIM and Exclusive Edition — uses the same BL263 footprint, voltage rail, and connector pinout. One cell covers all of them.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Z2 Pro mainboard. The BMS accepted handshake on first connection, charge IC ramped up without fault codes, and voltage held steady under sustained screen and modem load.
• Fuel gauge recalibration on first use: After installation, disable fast charging and run one full discharge-to-charge cycle at standard rate. The fuel gauge IC on the Z2 Pro calibrates its coulomb counter against the new cell's discharge curve during that first cycle — skipping it on a fresh cell causes percentage readings to drift for days.

Why the Z2 Pro reports wrong battery percentage after a cell swap

The fuel gauge IC stores a learned discharge curve from the old cell. When a new cell goes in, the IC still references that old curve, so the percentage shown on screen doesn't match actual charge state. One full discharge-to-shutdown followed by an uninterrupted charge to 100% forces the IC to rewrite its reference curve against the new cell. Until that cycle completes, expect the percentage to jump or stall at certain thresholds. After recalibration, readings stabilise within one or two additional cycles.

Sudden shutdown at 20–30% on the Z2 Pro after replacement

This happens when the cell voltage drops below the load threshold under a simultaneous modem and display draw — even though the fuel gauge still shows charge remaining. The BMS cuts output to protect the cell before the percentage reaches zero, which looks like a random crash. Run the fuel gauge recalibration cycle described above first. If shutdowns persist after two full cycles, check that the battery connector is fully seated — a partial connection raises contact resistance and accelerates voltage sag under load. A fully seated, recalibrated cell should hold voltage above 3.5V through the 20% range.