About this replacement
Asus K52 Series — 11.1V Li-ion Replacement Battery (A32-K52 / A42-K52)
This is an 11.1V Li-ion replacement battery for the Asus K52 notebook series. It fits the K52, K52f, K52jr, A52J, and over 179 additional compatible models. Capacity is 4400mAh (48.84Wh), matching the original cell specification.
- K52 and A52 series compatibility: These models share the same voltage rail, physical connector, and BMS handshake protocol across the K52 and A52 families. Part numbers A32-K52, A42-K52, A31-K52, A41-K52, A31-K42, A32-K42, A31-B53, and K52L681 all cross to this cell.
- Bench tested on actual hardware: We ran this battery through charge and discharge cycles on K52-series hardware. The BMS communicated correctly with the system board, charge acceptance was clean to 100%, and no protection-circuit trips occurred under full CPU and display load.
- Post-install calibration cycle: After fitting this cell, run one full discharge to hibernate-cutoff, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on K52-series notebooks.
BIOS reporting poor battery health immediately after replacement
The K52 BIOS reads health data stored in the battery's EEPROM. When a new cell arrives, that EEPROM contains factory default values that do not match the laptop's charge history, triggering a false poor-health flag. This is a data mismatch, not a fault with the cell. Running the full calibration cycle described above writes fresh data to the fuel gauge IC and clears the warning.
Laptop shuts down abruptly at 20–30% charge shown
This happens when the fuel gauge IC is still calibrated to the old, degraded cell. The new cell hits a voltage cliff under combined CPU and display load at a point the gauge still maps to 20–30%. The system reads a critical voltage drop and cuts power before the displayed percentage reaches zero. Run two to three full discharge-and-charge cycles so the fuel gauge IC learns the new cell's actual voltage curve, and the shutdowns will stop.