About this replacement
LG Xnote P420 / PD420 — 11.1V Li-ion Replacement Battery (SQU-1007)
This is an 11.1V, 4400mAh Li-ion battery replacing part numbers SQU-1007, SQU-1017, and EAC61538601. It fits the LG Xnote P420, Xnote PD420, S430, and Aurora ONOTE S430 series notebooks. Physical dimensions are 204.50 × 50.00 × 20.54mm — confirm clearance before fitting if your chassis has been modified.
- P420 and PD420 platform fitment: Both the P420 and PD420 share the same battery bay geometry, connector pinout, and BMS handshake protocol. SQU-1007 and SQU-1017 are interchangeable across these models because LG kept the same voltage rail and communication line through the series refresh.
- Bench tested on actual hardware: We ran this cell through a full charge-discharge cycle on a P420 chassis. The BMS handshake completed without fault codes, charge current stepped down correctly at the CV phase, and the protection circuit tripped at the expected low-voltage threshold under load.
- First-cycle calibration on the P420: After fitting, run the laptop on battery until it hibernates at low charge cutoff, then charge uninterrupted to 100% without using the machine. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on this platform.
Why the Xnote P420 shuts down at 20–30% after a battery swap
The P420's BIOS maps voltage curves from the original cell's EEPROM data. A new cell has different internal resistance and a slightly different discharge curve, so the fuel gauge IC miscalculates remaining capacity. The BIOS sees voltage drop under CPU and display load, interprets it as a depleted cell, and cuts power — even though real charge remains. Running two to three full discharge-to-hibernate and full-charge cycles lets the fuel gauge IC re-learn the new cell's curve and the shutdowns stop.
BIOS reporting battery Wh as incorrect or unknown after replacement
The system reads Wh rating from EEPROM data embedded in the battery's protection circuit board, not from the cells directly. If the EEPROM on the replacement carries a different rated value than the original, BIOS will display a mismatched or unknown Wh figure. This is a data mismatch between the PCB firmware and the BIOS table — not a fault with the cells themselves. Check the reported voltage is still 11.1V; if it is, the cell is functioning correctly regardless of what the Wh field displays.