Asus Zenbook UX330 Replacement Battery 11.55V 4500mAh

Asus Zenbook UX330 Series — 11.55V Li-Polymer Replacement Battery (C31N1610)

This 11.55V, 4500mAh (51.98Wh) lithium-polymer cell is a direct replacement for the Asus Zenbook UX330 ultrabook and its variants. It fits the UX330C, UX330U, UX330CA, and over 40 additional UX330-series configurations sharing the same OEM part number C31N1610. The battery slots into the existing bay and connects to the laptop's BMS via the same three-cell configuration the original used.

• UX330 series cell compatibility: Every UX330 variant in this family runs the same 11.55V three-cell polymer architecture with an identical connector pinout and BMS handshake protocol. Swapping between UX330C, UX330U, and UX330CA does not require firmware changes — the hardware interface is fixed across the series.
• Bench tested on actual hardware: We cycled this cell on a UX330UA under combined CPU and display load. The BMS held the charge curve within 2% of rated capacity across three full cycles, with no premature cutoff events on the charge rail.
• Post-install calibration on Zenbook: After fitting this battery, run the laptop down until it hibernates at low voltage, then charge uninterrupted to 100% without using the device. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on UX330 firmware.

BIOS reporting poor battery health immediately after replacement

The UX330 BIOS reads health data from EEPROM registers that were written by the original cell during its lifetime. When a new cell is installed, those registers do not automatically reset — the BIOS compares the new cell's charge data against old learned values and flags a mismatch as degraded health. This is a firmware reporting issue, not a fault with the replacement cell. Run one full discharge-to-hibernate cycle followed by an uninterrupted charge to 100%, and the BIOS learn cycle will rewrite those registers against the new cell's actual characteristics. After two or three cycles, the health indicator should read within normal range.

Zenbook UX330 shutting down at 20–30% remaining after battery swap

This happens because the fuel gauge IC is still calibrated against the old cell's discharge curve. Under full CPU and display load, the laptop draws enough current to cause voltage to drop faster than the uncalibrated gauge predicts — the system reads 25% but the actual cell voltage hits the cutoff threshold and the laptop shuts down. It is not a faulty battery. Run two full discharge cycles from 100% down to hibernate cutoff to let the fuel gauge IC map the new cell's actual voltage-to-capacity curve. After calibration, the OS percentage and real remaining capacity will align, and the unexpected shutdowns will stop. Target cell voltage at cutoff on the UX330 is approximately 9.0V under load.