Asus VivoBook Flip 12 Replacement Battery B31N1625 11.52V

Asus VivoBook Flip 12 TP203NAH — 11.52V Li-Polymer Replacement Battery (B31N1625)

This 11.52V, 3500mAh (40.32Wh) Li-Polymer cell replaces the original B31N1625 battery in the Asus VivoBook Flip 12 convertible touchscreen laptop. It fits the TP203NAH-BP054T, TP203NAH-BP094T, TP203NAH-BP056T, TP203MAH-1G, and over 26 additional TP203 variants. Connector orientation and BMS handshake protocol match the original Asus specification.

• TP203 series compatibility: All TP203NAH and TP203MAH units share the same 11.52V three-cell architecture, connector pinout, and BMS communication line — that is why one cell covers the full TP203 range without modification.
• Bench tested on actual hardware: We ran this cell on a TP203NAH under combined CPU load and display brightness at maximum. The BMS held charge termination at 100% without false-positive cutoff, and discharge stepped cleanly through each cell voltage stage without triggering an early shutdown.
• Post-swap recalibration on the TP203NAH: After fitting the new cell, run one full discharge until the laptop hibernates, then charge uninterrupted to 100%. This forces the BIOS battery learn cycle to reset against the new cell's actual capacity and clears the inaccurate health warning that appears on the first boot after every cell swap.

Why the TP203NAH BIOS reports poor battery health after a cell swap

The TP203NAH stores battery health data in EEPROM on the original cell. When you fit a replacement, the BIOS reads stale EEPROM values that do not match the new cell's actual charge state. This mismatch triggers a false "poor health" or "replace battery" warning in MyASUS and the Windows Battery Report. Running one full discharge-to-hibernate followed by an uninterrupted charge to 100% lets the BIOS rewrite its learn-cycle data against the new cell. After two to three full cycles, health reporting stabilises and the warning clears.

Laptop shutting down at 20–30% shown on the TP203NAH after replacement

This happens because the fuel gauge IC is still calibrated to the old cell's voltage-to-capacity curve. The new cell hits a voltage cliff under combined CPU and display load earlier than the IC expects, so the laptop cuts power while the gauge still shows charge remaining. The fix is a calibration cycle: discharge fully to hibernate, charge to 100% without interruption, then repeat once more. After two cycles the fuel gauge IC maps correctly to the new cell and the premature shutdown stops. If it persists beyond three cycles, check that battery charge limit mode is not active in MyASUS — this holds the ceiling at 80% and can compress the apparent usable range further.