LGIP-580A Compatible Battery for LG KU990 3.7V 1600mAh

LG KU990 Viewty — 3.7V Li-ion Replacement Battery (LGIP-580A)

This is a 3.7V, 1600mAh Li-ion replacement battery for the LG KU990 Viewty smartphone. It replaces the original LGIP-580A cell. Fits both the KU990 and Viewty KU990 variants.

• KU990 and Viewty KU990 compatibility: Both models use the same battery bay, connector pinout, and BMS handshake. The LGIP-580A spec — 3.7V nominal, single-cell Li-ion — is shared across the entire KU990 line, so one cell covers both variants without hardware modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on KU990 hardware. The BMS accepted the charge protocol without fault flags, held voltage above the low-battery cutoff threshold cleanly, and the phone's charge indicator tracked correctly through each cycle.
• Fuel gauge recalibration on first use: On first installation, disable any fast-charge mode and run one complete discharge-to-charge cycle. The KU990's fuel gauge IC calibrates against the cell's discharge curve on that first cycle — skipping it with high current into an uncalibrated cell causes the percentage readout to drift for weeks.

Sudden shutdown at 20–30% on the KU990 after a cell swap

This is a voltage cliff issue, not a capacity fault. Under modem transmission or screen load, the cell's internal resistance causes a brief voltage sag. If the phone's low-voltage cutoff threshold is hit during that sag, the device shuts down even though the fuel gauge still reads 20–30%. The root cause is the fuel gauge IC using the old cell's discharge curve to estimate remaining charge. One full discharge cycle — from 100% to automatic shutoff, then a full charge — lets the coulomb counter re-anchor to the new cell's actual curve and eliminates most premature shutoffs.

KU990 showing wrong battery percentage after replacement

The KU990's fuel gauge IC stores a learned discharge curve from the previous cell. A new cell with a different impedance profile makes that stored curve inaccurate immediately. The phone reads voltage and translates it to percentage using the old map, so the numbers jump or plateau at unexpected points. Fix this by running one full uninterrupted discharge cycle down to auto-shutdown, then charging to 100% without interruption — this forces the coulomb counter to write a new curve matched to the replacement cell.