About this replacement
Asus VivoBook Flip 12 TP203NA — 7.7V Li-Polymer Replacement Battery (C21N1625)
This is a 7.7V, 4850mAh (37.35Wh) Li-Polymer battery for the Asus VivoBook Flip 12 TP203NA series, including the BP034TS, BP055TS, and TP203NA-1E variants. It replaces OEM part numbers C21N1625 and 0B200-02470000. The original connector and cell footprint match the 170.00 x 134.80 x 6.40mm cavity in the TP203NA chassis.
- TP203NA series fit: All TP203NA variants share the same two-cell Li-Polymer configuration, 7.7V voltage rail, and C21N1625 BMS handshake. One SKU covers the full range without connector or firmware conflicts.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a TP203NA unit. The BMS accepted the cell, initiated a full charge sequence, and the BIOS recognised the battery without flagging an unknown device state.
- Post-install calibration on the TP203NA: After fitting, 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 swapping cells on this platform.
BIOS reporting poor battery health immediately after fitting a new cell
The TP203NA BIOS stores capacity and health data from the previous cell in its EEPROM. When a new cell is installed, the BIOS compares live readings against that stored profile and flags a mismatch as poor health. This is not a fault with the replacement cell — it is stale data. Run one full discharge-to-hibernate then a continuous charge to 100% to complete the battery learn cycle. After one or two calibration cycles, the BIOS health indicator updates to reflect the new cell accurately.
TP203NA shutting down at 20–30% charge shown on screen
This symptom appears when the fuel gauge IC has not yet calibrated against the new cell's actual voltage curve. The IC still references the old cell's discharge profile, so it underestimates remaining charge and triggers a low-voltage shutdown before the display reads zero. The fix is the same calibration process: discharge fully to hibernate-cutoff, then charge uninterrupted to 100%. After two to three full cycles, the fuel gauge IC realigns its state-of-charge calculation to the new cell, and shutdowns at elevated percentages stop.