About this replacement
Asus E406MA Series — 11.4V Li-Polymer Replacement Battery (C31N1721)
This is an 11.4V, 4800mAh Li-Polymer replacement battery for the Asus E406MA-1C and E406MA series Chromebooks. It replaces OEM part C31N1721 (also listed as 0B200-02830100). Slot it in when the original cell degrades and the laptop stops holding a charge away from the wall.
- E406MA series fit: The E406MA line shares a single battery bay spec — same connector pinout, same 11.4V three-cell configuration, and the same BMS handshake across the full model range including EB199TS, BV199TS, EB173T, and 149 additional variants. One part number covers all of them.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the E406MA platform. The BMS accepted the new cell without rejection flags, charge current ramped normally through CC/CV stages, and the protection circuit tripped correctly at low-voltage cutoff.
- First-cycle calibration on the E406MA: After fitting, run the battery down until the laptop hibernates, then charge uninterrupted to 100% before using it again. This forces the fuel gauge IC to map the new cell's actual capacity and clears the inaccurate health warning that appears in Chrome OS after every cell swap.
Why Chrome OS flags the replacement battery as poor health immediately after install
The E406MA stores battery health data in EEPROM on the old cell. When you swap in a new cell, Chrome OS reads the fresh EEPROM — with no charge history — and interprets it as a failed or unknown battery. The health warning is a firmware read artifact, not a fault with the replacement cell. Running one full discharge-to-hibernate followed by a full uninterrupted charge resets the BIOS battery learn cycle and resolves the flag.
E406MA shutting down at 20–30% charge shown on screen
This happens when the fuel gauge IC hasn't calibrated against the new cell's actual voltage curve. The IC still uses the old cell's discharge map, so it miscalculates the remaining charge and triggers shutdown early. It is not a fault in the replacement cell. Run two full discharge-to-hibernate cycles with uninterrupted charges to 100% in between — after the second cycle, shutdown should align with the gauge reading 0–5%.