LG Optimus LTE III BL-54SH Replacement Battery 3.8V 2600mAh

LG Optimus LTE III / F260 Series — 3.8V Li-ion Replacement Battery (BL-54SH)

This 3.8V, 2600mAh Li-ion cell replaces part number BL-54SH in the LG Optimus LTE III, F260, F260K, and F260S smartphones. It matches the original cell's connector, dimensions (68.00 × 48.40 × 5.55 mm), and BMS communication profile. Capacity comes from our product data at 9.88Wh — not inflated third-party figures.

• F260 platform compatibility: The F260K and F260S share the same voltage rail, physical connector, and BMS handshake as the base F260. All variants accept the BL-54SH footprint without modification to the battery bay or flex cable routing.
• Bench tested on actual hardware: We ran this cell through charge and load cycles on an F260 unit. The BMS accepted charge current without fault flags, held voltage above 3.6V under screen-on modem load, and tripped protection cleanly at the low-voltage cutoff threshold.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and complete one full discharge-charge cycle at standard current. This lets the fuel gauge IC learn the new cell's discharge curve before high-current charging pushes current into an uncalibrated state.

Sudden shutdown at 20–30% on the BL-54SH replacement cell

The Optimus LTE III's modem and display together draw sharp current spikes that can pull cell voltage below the BMS cutoff threshold — even when the fuel gauge still shows charge remaining. A new cell with an uncalibrated coulomb counter makes this worse because the reported percentage lags behind actual cell state. The BMS trips on real voltage, not reported percentage, so the phone cuts out before the OS sees 0%. One full slow discharge-charge cycle resets the coulomb counter and tightens the gap between reported and actual charge.

Phone will not power on after the replacement cell sat in storage

Li-ion cells that self-discharge below approximately 2.5V per cell trigger BMS lockout — a protective state that blocks charge current to prevent thermal runaway on a deeply discharged cell. The phone will show no response to the power button and no charging indicator. Connect to a wall charger rated at least 5V/1A and leave it undisturbed for 20–30 minutes; the BMS trickle-charges the cell back above the recovery threshold before allowing normal charge current. If the screen still shows nothing after 30 minutes, check the charger output voltage at the port — below 4.8V is insufficient to wake the protection circuit.