About this replacement
Asus Zenbook UX32 Series — 7.4V Li-Polymer Replacement Battery (C23-UX32)
This is a 7.4V 6500mAh (48.1Wh) Li-Polymer replacement battery for the Asus Zenbook UX32 series and VivoBook U38N ultrabooks. It uses OEM part numbers C23-UX32, 0B200-00070100, and 0B200-00070000. The slim 8.46mm cell profile matches the thin chassis these models share.
- UX32 and U38N platform fit: These models share the same 7.4V two-cell Li-Polymer architecture, connector pinout, and BMS communication protocol — which is why one cell covers both the Zenbook Prime UX32A and the VivoBook U38N-C4004H variants.
- Bench tested on actual hardware: We ran this cell on a UX32 board and confirmed the BMS handshake completed without fault flags. The charge controller accepted the cell immediately and cycled through charge termination cleanly at 8.4V.
- First-cycle calibration after swap: After fitting this battery, run the laptop down to hibernate cutoff under normal use, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that almost always appears after a cell swap on UX32 boards.
Why the UX32 BIOS reports poor battery health immediately after replacement
The UX32 firmware stores charge history and wear data from the old cell in its EEPROM-linked fuel gauge IC. When a new cell goes in, that stale data still reads as a degraded battery — even if the new cell is at full capacity. The BIOS health warning is not reflecting the new cell's condition; it is reflecting the old cell's history. Running one full discharge-to-hibernate then a full uninterrupted charge gives the fuel gauge IC enough data to overwrite the old cycle count and recalibrate against the new chemistry.
Laptop shuts down suddenly at 20–30% charge shown on screen
This happens when a degraded cell cannot sustain voltage under combined CPU and display load — the cell hits a voltage cliff faster than the fuel gauge predicted. The OS percentage shown is based on a fuel gauge estimate, not a live voltage read, so the displayed number lags behind the actual cell state. If the replacement cell still cuts out at 20–30% after installation, the fuel gauge has not yet recalibrated against the new cell's discharge curve. Complete two full discharge-to-hibernate cycles and the cutoff should move back toward 5% or lower, consistent with the cell's rated 48.1Wh capacity.