BL-42D1F LG G5 Replacement Battery 3.85V 2800mAh Li-ion

LG G5 / H830 / G5 Lite — 3.85V Li-ion Replacement Battery (BL-42D1F)

This is a 3.85V, 2800mAh Li-ion cell built to replace the BL-42D1F in the LG G5 and its variants, including the H830, G5 Lite, and H840. The G5's removable battery door makes swapping straightforward, but the fuel gauge IC needs attention after any cell replacement. Voltage and capacity figures come directly from product data — 10.78Wh total energy.

• G5 variant compatibility: The G5, H830, H840, and G5 Lite all share the same battery bay dimensions, connector pinout, and BMS handshake protocol — that is why one cell covers all these models without modification.
• Bench tested on actual hardware: We cycled this cell through a full discharge and charge on a G5 unit, confirmed the BMS handshake completed correctly, and verified the charge IC accepted the cell without triggering a fault flag.
• Fuel gauge recalibration on first use: On first installation, disable fast charging and run one complete discharge-to-charge cycle at standard rate. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging begins on an uncalibrated cell.

Sudden shutdown at 20–30% on the G5 after a cell swap

The G5's fuel gauge IC retains the discharge curve from the old, degraded cell. When a fresh cell is installed, the IC's coulomb counter still references the old curve, so it misjudges remaining voltage. Under high-draw moments — LTE transmission, screen-on bursts — the cell voltage drops below the BMS cutoff threshold before the OS reads 0%. One full slow-charge cycle forces the IC to relearn the new cell's voltage-to-capacity curve. After that cycle, shutdowns at inflated percentages stop.

Phone not powering on after the BL-42D1F sat in storage

Li-ion cells that drop below approximately 2.5V trigger a BMS lockout state to prevent cell damage. A G5 showing no response to the power button after storage is almost always in this state — not a dead cell. Connect the phone to a wall charger rated at least 1A and leave it for 20–30 minutes without pressing anything. The BMS recovery circuit will trickle current into the cell until it clears the lockout threshold, after which normal charging resumes and the phone powers on.