LG Optimus LTE III BL-54SH Replacement Battery 3.7V 1800mAh

LG Optimus LTE III / F260 Series — 3.7V Li-ion Replacement Battery (BL-54SH)

This is a 3.7V, 1800mAh Li-ion replacement cell for the LG Optimus LTE III and the F260 series, including the F260K and F260S variants. It replaces OEM part numbers BL-54SH, EAC62018301, BL-54SG, and EAC62018209. The battery slides into the same rear compartment as the original and uses the same three-contact connector.

• F260 series compatibility: The F260K, F260S, and base F260 share a common battery bay size and the same BMS contact layout as the LTE III. All four models run the same voltage rail and communicate charge state over the same three-pin interface, so one cell covers the whole group.
• Bench tested on actual hardware: We ran this cell through a full charge cycle on an LTE III unit. The BMS accepted the cell immediately, charge current stepped down correctly at 4.15V, and the protection circuit tripped cleanly at the low-voltage cutoff — no false cutoffs mid-cycle.
• Fuel gauge recalibration on first cycle: On first use, disable fast charging if your charger supports it and run one complete discharge down to auto-shutdown, then a full charge to 100%. The fuel gauge IC on the LTE III calibrates its coulomb counter against the actual discharge curve of the new cell — skipping this step causes the OS to read inaccurate percentages for weeks.

Sudden shutdown at 20–30% on the LG Optimus LTE III

The LTE III modem and display pull current in short, sharp bursts. An aged or degraded cell develops high internal impedance — when that burst hits, the cell voltage sags below the BMS cutoff threshold even though the reported percentage still reads 20–30%. The phone shuts off immediately because the protection circuit sees a valid undervoltage event, not a software glitch. A fresh 1800mAh cell with low internal resistance sustains voltage through those load spikes, and the shutdowns stop. After fitting the new cell, run one full discharge cycle so the fuel gauge IC maps the real voltage-to-capacity curve of the replacement.

Battery percentage jumping erratically after a cell swap

The LTE III fuel gauge IC stores a learned discharge curve from the previous cell. When a new cell goes in, the IC applies the old curve to a different cell chemistry profile, so percentage readings can jump 10–15 points up or down as load changes. This is not a fault with the replacement cell — it is the coulomb counter recalibrating. To reset it, charge the phone uninterrupted to 100%, then let the battery discharge to auto-shutdown without topping it up mid-cycle. One complete cycle is usually enough to bring percentage reporting back within 3–5% accuracy.