About this replacement
LG Optimus S / LS670 — 3.7V Li-ion Replacement Battery (LGIP-400N)
This 3.7V, 2800mAh Li-ion cell replaces the original LGIP-400N battery in the LG LS670 and Optimus S smartphones. It fits the same battery bay with no modification. Capacity figure is from the product specification, not estimated from a comparable cell.
- LS670 and Optimus S compatibility: Both models use the same physical bay geometry, contact pad layout, and voltage rail. The LGIP-400N part number covers the full production run of both variants, so one cell fits either handset without adapter or modification.
- Bench tested on actual hardware: We cycled this cell in an LS670 unit and monitored BMS handshake and charge IC behaviour through two full charge cycles. The protection circuit held cutoff at the correct thresholds and the charge IC accepted the cell without fault flags on both cycles.
- Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle before normal use. The fuel gauge IC on the LS670 references the previous cell's discharge curve — giving it one clean cycle against the new cell lets it recalibrate before high-current charging begins.
Sudden shutdown at 20–30% on the LS670 after a cell swap
This is a voltage cliff issue, not a capacity problem. The LS670's modem and display pull current spikes that the fuel gauge IC cannot predict if it is still calibrated to the old cell's discharge curve. When the new cell voltage drops under that combined load, it crosses the BMS cutoff threshold before the percentage counter reaches zero. The phone shuts down hard even though the displayed percentage suggests charge remains. One full discharge-and-recharge cycle resets the coulomb counter against the actual cell curve and the shutdowns stop.
Phone shows incorrect battery percentage after replacing the LGIP-400N
The fuel gauge IC on the LS670 learns discharge behaviour over time and stores that profile. When a new cell goes in, the stored profile no longer matches the actual cell chemistry, so the percentage reading drifts or jumps erratically. This is not a faulty battery — it is the coulomb counter working from stale data. Discharge the phone until it shuts off automatically, then charge it uninterrupted to 100% without removing the charger. After that single full cycle the gauge IC recalibrates and percentage readings stabilise.