Asus ZenBook Flip UX561UN C31N1703 Replacement Battery 11.52V

Asus ZenBook Flip UX561UN Series — 11.52V Li-Polymer Replacement Battery (C31N1703)

This is a 11.52V, 4500mAh (51.84Wh) Li-Polymer replacement battery for the Asus ZenBook Flip UX561UN-BO011T and related UX561 convertible laptops. It uses OEM part number C31N1703 (also listed as 0B200-02650100) and fits the three-cell configuration in this 2-in-1 chassis. The dimensions are 204.90 x 142.00 x 6.80mm — confirm your original cell matches before installing.

• UX561 series fit: The UX561UA, UX561UN, and related variants all share the same battery bay geometry, connector pinout, and BMS handshake protocol. Asus used a consistent three-cell Li-Polymer layout across this lineup, which is why a single part number covers more than 40 models in the series.
• Bench tested on actual hardware: We cycled this cell through charge and discharge under CPU and display load typical of the UX561 platform. The BMS communicated correctly with the ASUS EC firmware — charge accepted, cell voltage tracked within spec, and no fault codes were triggered during the test sequence.
• Post-install calibration on the ZenBook Flip: After fitting this cell, run one full discharge down to hibernate cutoff, then charge uninterrupted to 100% without using the laptop. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on UX561 hardware.

BIOS reporting battery health as poor immediately after replacement

The UX561 BIOS reads health data stored in the old cell's EEPROM and compares it against the new cell's reported state. A fresh cell has no charge history logged, so the EC interprets this as a fault rather than a clean slate. This triggers the "battery health is poor" or "consider replacing your battery" message even though the cell is new. Run the ASUS Battery Health Charging utility or complete one full learn cycle — discharge to hibernate, then charge to 100% — to write fresh EEPROM baseline data and clear the warning.

Laptop shutting down unexpectedly at 20–30% charge shown

This happens when the fuel gauge IC has not yet calibrated against the new cell's actual voltage curve. The displayed percentage is based on stale data from the previous cell, so the OS shows 25% while the real cell voltage has already dropped below the BMS cutoff threshold under CPU and display load. The BMS protects the cell by cutting power — it reads as a crash, not a graceful shutdown. Complete two to three full charge and discharge cycles so the fuel gauge IC can map the new cell's voltage-to-capacity curve accurately.