LG Optimus C40 Replacement Battery BL-41ZH 3.7V 1500mAh

LG Optimus L50 / Leon Series — 3.7V Li-ion Replacement Battery (BL-41ZH)

This is a 3.7V, 1500mAh Li-ion replacement battery for the LG Optimus C40, Optimus L50, Leon, and Leon 4G smartphones. It uses OEM part number BL-41ZH (also cross-referenced as EAC62378407, BL-41ZHB, and EAC62778201). If your original battery no longer holds a charge or causes unexpected shutdowns, this cell matches the original voltage rail and connector layout.

• Leon and Optimus C40/L50 platform fit: These models share the same battery bay dimensions, 3.7V nominal voltage rail, and connector pinout. The BMS on each device handshakes with the same cell chemistry, so no firmware workaround or adapter is needed across the lineup.
• Bench tested on actual hardware: We ran this cell through full charge and load cycles on the Leon platform. The BMS accepted the cell without fault flags, charge current stepped down correctly at full state of charge, and the protection circuit tripped cleanly at the low-voltage cutoff threshold.
• Fuel gauge recalibration on first cycle: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle. The fuel gauge IC on these LG models calibrates against the cell's discharge curve on that first full pass — skipping this step often causes the percentage readout to drift or jump erratically for days.

Sudden shutdown at 20–30% on the Leon and Optimus C40

This is a voltage cliff problem, not a capacity problem. When the modem transmits or the screen brightness spikes, the cell must deliver a short burst of high current. An aged or degraded cell cannot hold voltage under that load — it collapses below the BMS cutoff threshold even though the fuel gauge still reads 20–30%. A fresh 1500mAh cell with lower internal resistance handles the current spike without the voltage drop, so the phone no longer cuts out. After fitting the new cell, confirm the open-circuit voltage reads at or above 3.7V before first boot.

Phone shows wrong battery percentage after cell swap

The coulomb counter and fuel gauge IC in these LG devices hold a calibration map built around the old cell's discharge curve. After a replacement, that map no longer matches the new cell, so percentage readouts jump, stall, or drop suddenly. The fix is one full uninterrupted discharge-to-charge cycle with fast charging disabled. By the end of that cycle, the fuel gauge IC has rewritten its reference points against the new cell and the percentage display stabilises.