Asus Taichi 21 Replacement Battery 11.1V 3050mAh C32-TAICHI21

Asus Taichi 21 Series — 11.1V Li-Polymer Replacement Battery (C32-TAICHI21)

This is an 11.1V, 3050mAh (33.86Wh) lithium-polymer battery for the Asus Taichi 21 ultrabook. It fits the Taichi 21, 21-DH51, 21-DH71, and 21-UH71. The Taichi 21 is a dual-screen hybrid that runs as both a laptop and a tablet, and this battery slots directly into that thin chassis without modification.

• Taichi 21 series compatibility: The DH51, DH71, and UH71 variants all share the same battery bay dimensions and the same C32-TAICHI21 connector pinout. The BMS handshake uses the same SMBus protocol across the whole line, so the EEPROM data transfers correctly on any Taichi 21 unit.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Taichi 21 unit. The BMS reported correct voltage at each state-of-charge step, and the charging circuit reached full capacity without tripping the overcurrent cutoff.
• First-cycle calibration on the Taichi 21: After installing, 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 the system logs after every cell swap.

BIOS reporting poor battery health immediately after replacing the Taichi 21 cell

The Taichi 21 BIOS stores battery health data in EEPROM tied to the original cell. When a new cell goes in, the BIOS compares live readings against that stored baseline and flags the battery as degraded or unknown. This is a data mismatch, not a fault with the replacement cell. Running a full discharge-to-hibernate followed by an uninterrupted full charge forces the BIOS to rewrite its learn cycle data against the new cell. After one or two full cycles, the health status corrects itself.

Taichi 21 shutting down at 20–30% charge shown on screen

The Taichi 21's dual-screen setup draws significant power under load — both displays active plus CPU spikes create a combined current draw that exposes voltage sag in a degraded or uncalibrated cell. If the laptop cuts off while the gauge still shows 20–30%, the cell voltage is dropping below the BMS cutoff threshold under that load before the gauge catches up. This is a calibration gap, not a defective cell. Run two full discharge-to-hibernate cycles and charge fully each time — by the second cycle the fuel gauge IC recalibrates to the new cell's actual voltage curve and the early shutdowns stop. Confirm the cell is recovering correctly by checking voltage in BIOS: it should read above 10.8V at 20% state of charge.