About this replacement
LG P940 / Prada 3.0 — 3.7V Li-ion Replacement Battery (BL-44JR)
This is a 3.7V, 1200mAh Li-ion replacement battery for the LG P940 Optimus and the LG Prada 3.0 (K2 / SU880). It uses OEM part number BL-44JR and shares the same connector, dimensions, and BMS handshake as the original cell. Voltage and chemistry match the stock specification exactly.
- P940, Prada 3.0, K2, SU880 platform fit: These models share the same battery bay geometry, 3.7V nominal rail, and BL-44JR connector layout. The BMS communication protocol is identical across the group, so no firmware or hardware adaptation is needed.
- Bench tested on actual hardware: We cycled this cell through the P940's charge IC and monitored BMS handshake. The protection circuit engaged correctly at cutoff voltage, and the charge controller accepted the cell without error flags on the second cycle after the fuel gauge IC began recalibrating.
- First-cycle fuel gauge reset on the P940: After fitting this cell, let the phone discharge fully to auto-shutdown, then charge to 100% uninterrupted. This gives the P940's fuel gauge IC one clean reference cycle against the new cell's discharge curve before Android begins reporting state-of-charge.
Why the P940 reports wrong battery percentage after a cell swap
The P940 uses a coulomb counter that stores calibration data tied to the old cell's impedance and discharge curve. When you fit a new cell, that stored curve no longer matches what the hardware is reading. The phone's reported percentage drifts — often showing 40% when the cell is near cutoff. One full discharge-to-shutdown followed by an uninterrupted charge to 100% resets the counter reference and brings the readout back into alignment.
Sudden shutdown at 20–30% on the replacement cell
This happens when the modem, screen, or both pull current that the cell can't sustain at that state-of-charge, causing voltage to sag below the BMS cutoff threshold — even though the fuel gauge still shows charge remaining. It's a calibration gap, not a faulty cell. The BMS trips at approximately 3.0V per cell under load before the gauge catches up. Run one full discharge cycle without interruption and the cutoff events should stop occurring at falsely high percentages.