BQ U Plus Replacement Battery 3.85V 2950mAh Li-Polymer 3080

BQ U Plus / Aquaris U Series — 3.85V Li-Polymer Replacement Battery (3080)

This is a 3.85V, 2950mAh Li-Polymer replacement battery for the BQ U Plus, Aquaris U, and U Lite smartphones. It replaces OEM part number 3080. Use it when the original cell has lost capacity, fails to hold charge, or causes unexpected shutdowns.

• U Plus, Aquaris U, and U Lite compatibility: All three models share the same battery bay dimensions, connector pinout, and BMS handshake protocol — the 3080 part number is common across the range. The cell dimensions are 82.00 × 61.20 × 3.50 mm; verify the bay is clear of debris before fitting.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on BQ Aquaris U hardware. The BMS accepted the cell without rejecting the charge handshake, and voltage held steady through screen and modem load draws without triggering early cutoff.
• Fuel gauge recalibration on first use: After fitting this cell, disable fast charging and run one full discharge-to-charge cycle at standard current. The fuel gauge IC on the BQ U Plus reads against a stored discharge curve — a new cell with a different internal resistance will skew that curve until one full cycle resets the coulomb counter baseline.

Why the BQ U Plus reports wrong battery percentage after a cell swap

The fuel gauge IC on the BQ U Plus uses a coulomb counter calibrated against the original cell's discharge curve. A replacement cell carries different internal resistance, so the IC maps voltage to percentage incorrectly until it recalibrates. You may see the percentage jump several points or the indicator stall at a fixed value. One complete discharge down to auto-shutdown followed by a full charge cycle at standard current resets the counter to the new cell's actual curve.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage cliff issue, not a capacity fault. Under peak load — active modem, bright screen, GPS — the cell's terminal voltage drops sharply below the BMS cutoff threshold even though the reported percentage still reads in the twenties. The fuel gauge IC has not yet mapped the new cell's voltage-to-capacity curve accurately, so it fails to predict the cliff. Run two full discharge-charge cycles at standard current; the IC recalibrates its low-voltage cutoff prediction and the premature shutdowns stop. If they persist after two cycles, check that the connector is fully seated and measure resting voltage — it should read at or above 3.85V after a full charge.