About this replacement
Asus FX504 Series — 11.4V Li-ion Replacement Battery (B31N1726)
This is a 11.4V 4100mAh (46.74Wh) Li-ion battery for the Asus FX504 gaming laptop line, including the FX504G, FX504GE, and related variants. It replaces OEM part B31N1726 and fits the same physical bay with the original connector orientation. Voltage and cell count match the stock specification exactly.
- FX504 platform compatibility: The FX504, FX504G, and FX504GE all share the same battery bay dimensions, 3-cell 11.4V rail, and EC connector pinout. One cell replaces all three variants without modification.
- Bench tested on actual hardware: We cycled this cell on an FX504GE under sustained CPU and GPU load. The BMS held charge cutoff at 12.6V and low-voltage protection tripped correctly before cell damage could occur.
- First-cycle calibration on the FX504: After installing, run one full discharge until the laptop hibernates, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the false health warning the EC logs after every cell swap.
BIOS reporting poor battery health immediately after swap
The FX504's embedded controller reads health data from the battery's EEPROM, which still carries the degraded metrics written by the old cell. The new cell hasn't yet written its own charge cycles to that register. One full discharge-to-hibernate followed by a complete uninterrupted charge gives the EC enough data to overwrite the stale EEPROM values. After that cycle, the BIOS health status clears on its own — no software tool needed.
Laptop shuts down at 20–30% charge shown on screen
This is a fuel gauge IC calibration fault, not a cell defect. The gauge IC was calibrated against the old degraded cell and its voltage-to-capacity curve no longer maps accurately to the new chemistry. Under heavy CPU and GPU load, the new cell delivers strong current but the gauge misreads the voltage slope and fires a shutdown before the actual cutoff. Run two full discharge-to-hibernate cycles back-to-back and the IC recalibrates its internal curve. The shutdown threshold should stabilise below 5% after the second cycle.