About this replacement
LG KM380 / KF300 Series — 3.7V Li-ion Replacement Battery (LGIP-330GP)
This is a 3.7V, 650mAh Li-ion cell that replaces the original LGIP-330GP battery in the LG KM380, KT520, KF300, KF240, and compatible models. It fits the same physical slot and connector as the factory cell. Use it when the original battery no longer holds enough charge to keep the phone running through normal daily tasks.
- KM380 / KF300 platform fit: These models share the same battery bay dimensions (54.19 × 33.57 × 4.00mm), connector pinout, and BMS communication protocol — that is why one cell covers the full range. Voltage rail is 3.7V nominal across all listed variants.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the KM380 platform. The BMS handshake completed on first connection, charge termination triggered correctly at full capacity, and the protection circuit responded to simulated over-discharge conditions as expected.
- Fuel gauge recalibration on first use: After fitting this cell, run one complete discharge down to automatic shutdown, then charge uninterrupted to 100% without interrupting the cycle. The KM380 fuel gauge IC maps its coulomb counter to the new cell's discharge curve during this first full cycle — skip it and the percentage readout will drift.
Why the KM380 reports wrong battery percentage after a cell swap
The fuel gauge IC on the KM380 stores a learned discharge curve from the previous cell. When you install a new cell, that stored curve no longer matches the actual voltage-to-capacity relationship of the replacement. The IC continues using the old data, so reported percentage drifts away from real state of charge. One full discharge-to-shutdown followed by an uninterrupted charge to 100% forces the coulomb counter to resynchronise against the new cell's actual curve.
Sudden shutdown at 20–25% on the KM380 after replacement
This happens when the cell voltage drops sharply under load — typically during a call or screen-on activity — faster than the fuel gauge IC predicts. The phone hits the low-voltage cutoff threshold before the displayed percentage reaches zero. It is not a faulty cell; it is the fuel gauge reading from a stale calibration profile. Complete one full discharge-charge cycle and confirm resting voltage reads 3.7V on a multimeter before reassembly if the symptom persists.