About this replacement
Asus Chromebook C436FA — 11.55V Li-Polymer Replacement Battery (C31N1845)
This is an 11.55V, 3600mAh (41.58Wh) Li-Polymer battery for the Asus Chromebook C436FA. It replaces OEM part numbers C31N1845 and 0B200-03570000. Fit this when the original cell no longer holds charge or the system reports degraded battery health.
- C436FA platform fit: The C436FA uses a three-cell Li-Polymer pack on an 11.55V rail with a dedicated fuel gauge IC. Any replacement must match that voltage and cell count — a mismatch trips the BMS and blocks charging entirely.
- Bench tested on actual hardware: We ran this cell on a C436FA unit and confirmed full charge acceptance to 100%, stable BMS handshake, and no cutoff errors during a CPU-plus-display load cycle. The EEPROM handshake completed cleanly on first boot.
- Post-install discharge cycle on the C436FA: After fitting, run the Chromebook down to the automatic hibernate cutoff — do not force shutdown — then charge uninterrupted to 100%. This triggers the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on this model.
Why the C436FA shuts down at 20–30% after a battery swap
The fuel gauge IC on the C436FA maps voltage curves from the old cell. When a new cell is installed, those stored curves no longer match the actual discharge slope of the fresh chemistry. The system reads a rapid voltage drop under CPU-plus-display load and interprets it as a near-empty cell, triggering shutdown well before the real cutoff. Running two full discharge-to-hibernate and charge-to-100% cycles recalibrates the fuel gauge IC against the new cell's actual voltage curve.
BIOS reporting battery health as poor or unknown immediately after install
The C436FA's BIOS pulls health data from EEPROM registers that were written by the original cell during its service life. A replacement cell ships with fresh EEPROM data, which the BIOS flags as a mismatch — showing "poor health" or "0%" on first boot. This is not a fault with the cell. Boot into the Chromebook's battery settings after completing a full learn cycle — charge to 100% uninterrupted — and the health status corrects itself as the BIOS overwrites the stale EEPROM values.