LG P880 Optimus 4X HD Replacement Battery 3.7V 1400mAh BL-53QH

LG Optimus 4X HD / Optimus LTE II — 3.7V Li-ion Replacement Battery (BL-53QH)

This is a 3.7V, 1400mAh Li-ion replacement cell for the LG P880 (Optimus 4X HD) and Optimus LTE II / LTE 2 series. It slots into the original battery compartment using the same OEM contact layout and BMS pinout as part number BL-53QH. Capacity is rated at 1400mAh (5.18Wh) — matching the stock specification.

• P880 and Optimus LTE II platform fit: Both the Optimus 4X HD and Optimus LTE II share the same battery bay dimensions and three-contact BMS interface. The fuel gauge IC on both boards reads the same discharge curve, so one cell covers both variants without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the P880 board. The BMS accepted the cell on first insertion, charge current ramped normally, and the protection circuit tripped at the correct over-voltage threshold without latching.
• Fuel gauge recalibration on first use: After installing this cell, disable any fast-charge adapter and run one full discharge-to-charge cycle on a standard 5V charger. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging is applied to an uncalibrated cell.

Sudden shutdown at 20–30% on the P880 after a cell swap

The Optimus 4X HD's fuel gauge IC retains the old cell's discharge model in memory after a swap. When the phone hits a load spike — LTE radio handoff, screen at full brightness — the new cell's actual voltage drops below the model's predicted floor earlier than expected. The board interprets this as a critical low-voltage event and cuts power immediately, even though the percentage displayed was still 20–30%. One complete discharge below 3.5V followed by a full charge resets the coulomb counter and aligns the model to the new cell's curve.

Phone reports 100% immediately after install but drops to 60% within minutes

This is the fuel gauge IC reading residual charge state data from the old cell, not from the new one. The coulomb counter hasn't been zeroed against the replacement cell's actual charge level. The fix is straightforward: drain the phone until it powers off on its own, then charge uninterrupted to 100% without removing the charger. After that single cycle, the percentage display will track the real cell state. Confirm the recalibration held by checking that the phone reaches a resting voltage of approximately 4.2V at reported 100%.