UMIDIGI A3 Replacement Battery 3.85V 3100mAh 1ICP/5/82/75

UMI UMIDIGI A3 — 3.85V Li-Polymer Replacement Battery (1ICP/5/82/75)

This 3.85V, 3100mAh Li-Polymer cell replaces the original battery in the UMIDIGI A3 smartphone. It matches the OEM part number 1ICP/5/82/75 and fits the physical dimensions of the A3 battery bay at 75.30 × 61.60 × 4.62mm. If your A3 shuts down unexpectedly, charges slowly, or no longer holds a full charge, this cell is a direct swap.

• UMIDIGI A3 fitment: The A3 uses a single-cell Li-Polymer pack with a specific connector pinout that carries both power and fuel gauge data. This replacement matches that connector and communicates with the A3's charge IC, so the battery status display and charge cut-off logic function as they should.
• Bench tested on actual hardware: We ran charge and discharge cycles on the A3 platform and confirmed the BMS accepted the cell without triggering a charge fault. Capacity read-back from the fuel gauge IC landed within normal tolerance of the rated 3100mAh after two full cycles.
• Fuel gauge recalibration on first use: After fitting this cell, disable fast charging in the A3 settings and run one complete discharge down to auto-shutdown, then charge to 100% at standard rate. This gives the coulomb counter a clean reference cycle so percentage readings stay accurate under modem and display load.

Why the UMIDIGI A3 reports wrong battery percentage after a cell swap

The A3 tracks charge state using a fuel gauge IC that builds a model of the cell's discharge curve over time. When the old, degraded cell is replaced, the IC still holds the degraded cell's curve in memory. Until it recalibrates against the new cell, it will over- or under-report the remaining charge. The fix is one full uninterrupted discharge-charge cycle at standard current — no top-up charges halfway through. After that cycle, the IC resets its reference and percentage readings stabilise.

Sudden shutdown at 20–30% remaining on the new cell

This happens when the fuel gauge IC has not yet mapped the new cell's voltage cliff — the point where cell voltage drops sharply under load from the modem or screen. The IC predicts more capacity remains, but the cell voltage sags below the BMS cutoff threshold under that load. The phone shuts off before the displayed percentage reaches zero. Run the recalibration cycle described above, and confirm the A3 is not in a high-brightness or active data session during the first discharge, as that increases load variance. After calibration, the IC anticipates the voltage drop correctly and the shutdown threshold moves to below 5%.