Asus X570 Replacement Battery 11.4V 4050mAh B31N1723

Asus X570 / FX570UD Series — 11.4V Li-ion Replacement Battery (B31N1723)

This is an 11.4V Li-ion battery rated at 4050mAh (46.17Wh), replacing OEM part B31N1723 in the Asus X570 series. It fits the X570, X570ZD, FX570UD, and X570UD, among others. If the original cell has swollen, dropped to near-zero capacity, or the laptop no longer holds a charge off AC, this is the direct cell replacement.

• X570 and FX570UD platform fit: These models share the same three-cell Li-ion configuration, B31N1723 part number, and the same EC-controlled charge circuit. The connector pinout and BMS handshake protocol match across the X570 and FX570UD variants, so the same cell works across all listed models without firmware workarounds.
• Bench tested on actual hardware: We ran this cell on an X570ZD and monitored charge acceptance through the EC. The BMS accepted a full 0–100% charge cycle, current tapered correctly at top-of-charge, and the EC reported cell voltage within expected range at every 10% state-of-charge interval.
• Post-install calibration on the X570: 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 the X570 platform.

Why the X570 BIOS flags a new battery as poor health immediately after install

The X570 EC reads health data from the old cell's EEPROM and stores it. When a new cell goes in, the EC has no matching EEPROM baseline, so it reports degraded or unknown status before any calibration has run. This is not a fault with the replacement cell — it is a mismatch between stored data and the new cell's fresh chemistry profile. Running one full discharge-to-hibernate then an uninterrupted charge to 100% allows the EC to write new baseline data. After one to two full cycles, the health report normalises.

X570 shutting down at 20–30% battery shown on screen

This happens when the fuel gauge IC's stored discharge curve no longer matches the actual cell voltage behaviour under load. During heavy CPU and display draw, the cell voltage drops faster than the IC predicts, crossing the low-voltage cutoff while the OS still shows significant charge remaining. It is a calibration gap, not a defective cell. Force a full discharge to hibernate-cutoff, then charge to 100% without interruption — repeat this two to three times until the gauge tracks actual cell voltage accurately down to shutdown, which the EC triggers at approximately 10.0V under load.