About this replacement
Asus C423NA-DH02 — 7.7V Li-Polymer Replacement Battery (C21N1808)
This is a 7.7V, 4850mAh (37.35Wh) Li-Polymer battery for the Asus Chromebook C423NA-DH02 and related C423NA and C523NA variants. It replaces OEM part numbers C21N1808, 0B200-03060000, and 0B200-03130000. If the original cell no longer holds charge or the Chromebook dies quickly off the charger, this swap restores full portability.
- C423NA and C523NA series fit: These models share the same two-cell Li-Polymer pack, 7.7V nominal rail, and connector pinout. The BMS handshake protocol is identical across the NA-series board revision, so the same cell works across DH02, BV0054, EB0049, and the 0021AN4200 SKUs without firmware conflict.
- Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the C423NA platform. The BMS accepted the pack without fault flags, charge current stepped down correctly at 4.35V per cell, and the protection circuit triggered cleanly at low-voltage cutoff.
- Post-install calibration cycle: After fitting this battery, drain the Chromebook completely until it shuts off on its own, then charge uninterrupted to 100% without using the device. This resets the fuel gauge IC against the new cell's actual capacity and clears the inaccurate battery health warning that appears in Chrome OS after every cell swap.
Chrome OS reporting battery health as poor immediately after swap
Chrome OS reads battery health data from EEPROM registers that still carry the old cell's wear metrics. A fresh cell installed into a board with aged EEPROM data will show degraded health even at 100% charge. Running one full discharge-to-shutdown followed by an uninterrupted charge to 100% forces the fuel gauge IC to rewrite its learned parameters against the new cell. After one or two complete cycles, the health status in the battery diagnostics page updates to reflect actual capacity.
Chromebook shuts down abruptly at 20–30% charge shown on screen
This happens when the fuel gauge IC was calibrated against the old, worn cell and has not yet mapped the voltage curve of the new one. Under combined CPU and display load, voltage drops faster than the uncalibrated gauge predicts, and the BMS cuts power before the displayed percentage reaches zero. It is not a fault with the replacement cell. Complete the calibration cycle described above — discharge fully to automatic shutdown, then charge to 100% — and the gauge will track the new cell's voltage curve accurately from around 4.30V down to the cutoff threshold.