About this replacement
Asus VivoBook E203MA — 7.6V Li-Polymer Replacement Battery (0B200-02500000)
This 7.6V, 4900mAh (37.24Wh) lithium-polymer battery fits the Asus VivoBook E203MA and the broader E203 series notebook lineup. It replaces OEM part numbers 0B200-02500000, B31N1629, and C21N1629. The slim 4.35mm cell profile matches the original chassis clearance.
- E203 series fit: The E203, E203MA-1A, E203MA-1B, and 229+ additional E203 variants share the same 7.6V two-cell Li-Polymer pack, connector pinout, and BMS handshake protocol — one cell covers the full lineup.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on an E203MA unit. The BMS negotiated charge termination correctly at full voltage, and the protection circuit tripped as expected at low-cell cutoff with no false shutdowns during the test.
- First-cycle recalibration on the E203MA: After fitting this battery, run the laptop down to hibernate cutoff under normal use, then charge uninterrupted to 100%. This forces the BIOS battery learn cycle to reset against the new cell and clears the false health warning that appears after every cell swap.
BIOS reporting poor battery health immediately after fitting a new cell
The E203MA BIOS reads health data from EEPROM registers that were written against the old cell's cycle count and capacity history. A fresh cell has no matching history, so the BIOS flags it as degraded on first boot — this is a data mismatch, not a faulty battery. Running one complete discharge-to-hibernate followed by an uninterrupted full charge resets those registers. After two to three cycles the health reading normalises to a figure that reflects the new cell.
Laptop shutting down at 20–30% charge shown on the E203MA
This happens when the fuel gauge IC has not yet calibrated against the new cell's actual discharge curve. The IC was mapped to the old cell's voltage-to-capacity relationship and misjudges the remaining charge at load. Under combined CPU and display load, the real cell voltage drops past the BMS cutoff threshold before the percentage counter reaches zero. Run two full discharge-to-hibernate cycles and the fuel gauge relearns the correct voltage cliff point — shutdowns at false percentages stop after that.