About this replacement
Asus E202SA / R206SA Series — 11.4V Li-Polymer Replacement Battery (B31N1503)
This is an 11.4V, 4050mAh (46.17Wh) Li-Polymer battery for the Asus VivoBook E202SA and R206SA series laptops. It replaces OEM part numbers B31N1503 and 0B200-01690000. Confirmed fit for E202SA-1A, E202SA-1E, E202SA-7B, and R206SA, among other variants in this lineup.
- E202SA and R206SA platform fit: These models share the same three-cell Li-Polymer pack architecture, 11.4V rail, and battery connector pinout. The BMS handshake protocol and charge cutoff thresholds are identical across this series, which is why one SKU covers all listed variants.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on an E202SA unit. The BMS initialised correctly, charge termination triggered at the expected 13.05V cell ceiling, and the protection circuit responded to overcurrent conditions without false trips.
- Post-install discharge cycle on E202SA: After fitting this battery, run the laptop down to automatic hibernate — do not manually shut it off early — then charge uninterrupted to 100%. This single full cycle resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on this platform.
Why the E202SA reports poor battery health immediately after a new cell is fitted
The BIOS on this platform stores charge cycle counts and capacity data in EEPROM tied to the original cell. When a new battery is installed, that stored data no longer matches the new cell's actual capacity, so the BIOS flags it as degraded. This is not a fault with the replacement — it is a calibration mismatch. One full discharge-to-hibernate followed by an uninterrupted charge to 100% forces the BIOS to rewrite that EEPROM data against the new cell. After that cycle, the health indicator clears on most E202SA units.
Laptop shuts down at 20–30% shown on the E202SA after battery swap
This happens when the fuel gauge IC has not yet calibrated against the new cell's actual discharge curve. The gauge reads a voltage that looks like 25% remaining, but under combined CPU and display load, the cell voltage drops sharply below the BMS cutoff threshold — the system shuts down before the gauge updates. It is not a faulty battery. Run two to three full discharge-to-hibernate cycles and the fuel gauge IC will remap the curve against the new chemistry. After calibration, shutdowns at false percentages stop, and the gauge tracks accurately down to the real cutoff near 10.5V total pack voltage.