Lenovo ZUK 2 BL268 Replacement Battery 3.85V 3400mAh

Lenovo Zuk 2 / Z2131 — 3.85V Li-Polymer Replacement Battery (BL268)

This is a 3400mAh 3.85V Li-Polymer cell that replaces the original BL268 battery in the Lenovo Zuk 2, Z2 Rio 2016 Edition, and Z2131 smartphones. The cell matches the original voltage rail and physical footprint at 104.30 × 38.90 × 4.60 mm. Install it when the original cell no longer holds a charge or causes unexpected shutdowns.

• Zuk 2 / Z2131 platform fit: The Z2131 hardware shares a single battery bay spec across the Zuk 2 and Z2 Rio 2016 Edition — same connector orientation, same BMS handshake voltage, same 3.85V nominal rail. One cell part number covers all three variants.
• Bench tested on actual hardware: We cycled the BL268 replacement through charge and discharge on the Z2131 board. The onboard charge IC accepted the cell without fault flags, and the BMS cutoff triggered correctly at the low-voltage threshold during deep discharge testing.
• Fuel gauge recalibration on first use: After fitting this cell, disable fast charging for one full discharge-charge cycle. The fuel gauge IC on the Zuk 2 is calibrated to the old cell's discharge curve — running a single slow cycle first lets the coulomb counter reset its reference points before high-current charging begins.

Sudden shutdown at 20–30% on the Zuk 2 after a cell swap

The Zuk 2's modem and display draw a combined current spike that the fuel gauge IC cannot predict accurately until it has mapped the new cell's discharge curve. If the replacement cell's internal impedance differs from the original, voltage sags sharply under that load — dropping below the hardware shutdown threshold even though the reported percentage still reads mid-range. This is a calibration issue, not a faulty cell. Run two full slow-charge cycles and the fuel gauge IC will remap the voltage-to-percentage relationship against the actual cell behaviour.

OS battery percentage jumping erratically after BL268 replacement

The Android fuel gauge IC on the Z2131 stores learned discharge data from the old cell in non-volatile memory. After a cell swap, the coulomb counter is feeding real current data into a lookup table built for a different cell — percentages jump because the mapping no longer fits. Clear the battery stats partition in recovery mode, then run the phone from 100% down to automatic shutdown without interruption. After that single full cycle, the IC rebuilds its reference table against the new BL268 cell and percentage readings stabilise.