LG Gray C800 Replacement Battery BL-48LN 3.7V 2400mAh

LG Gray C800 / myTouch Q Series — 3.7V Li-ion Replacement Battery (BL-48LN)

This is a 3.7V, 2400mAh Li-ion battery for the LG Gray C800, myTouch Q, and myTouch Q 4G smartphones. It replaces OEM part number BL-48LN. Fit the new cell when the original no longer holds a charge or the phone shuts off unexpectedly under load.

• Gray C800, myTouch Q, myTouch Q 4G coverage: All three models share the same BL-48LN form factor, connector pinout, and BMS handshake protocol. One replacement cell covers the full platform without modification.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the myTouch Q platform. The BMS accepted the cell immediately, voltage held steady through screen-on and modem-active load, and the protection circuit triggered correctly at the low-voltage cutoff threshold.
• Fuel gauge recalibration on first use: On first installation, disable fast charging and run one complete discharge-to-charge cycle at standard current. The fuel gauge IC is calibrated to the old cell's discharge curve — one full cycle lets it recalibrate against the new cell before high-current charging begins.

Why the myTouch Q reports wrong battery percentage after a cell swap

The LG fuel gauge IC uses a coulomb counter that tracks charge relative to a learned discharge curve from the previous cell. When you swap to a new 2400mAh cell, that stored curve no longer matches the actual cell chemistry. The OS reads from the fuel gauge register, not the cell directly, so the reported percentage reflects the old model. One full discharge from 100% to automatic shutoff — without interruption — forces the IC to remap the curve to the new cell. After that cycle, percentage readings stabilise.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage cliff failure, not a capacity issue. Under combined screen, modem, and app load, cell voltage drops faster than the fuel gauge predicts — especially before the first recalibration cycle. When cell voltage falls below the BMS protection threshold under that load, the phone cuts power immediately even though the reported percentage looks safe. Run the recalibration cycle first. If shutdowns continue after two full cycles, check that resting cell voltage holds above 3.6V after a full charge.