{"product_id":"asus-vivobook-s300-replacement-battery-111v-4000mah-li-polymer","title":"Asus VivoBook S300 Replacement Battery C31-X402 11.1V 4000mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eAsus VivoBook S300 \/ S400 Series — 11.1V Li-Polymer Replacement Battery (C31-X402)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is an 11.1V, 4000mAh (44.4Wh) Li-Polymer battery for the Asus VivoBook S300, S400, S400C, and S400CA. It replaces OEM part numbers C31-X402, 0B110-00210000, C21-X401, and C31X402. If your original cell is swelling, failing to charge, or no longer holding power, this is a direct cell swap.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eVivoBook S300 \/ S400 platform fit:\u003c\/strong\u003e\n    These models share the same 11.1V three-cell Li-Polymer battery bay, connector pinout, and BMS communication protocol. The S400C and S400CA variants use the same pack form factor — 302 x 69.42 x 7.82mm — with the same fuel gauge IC handshake, so one SKU covers the full lineup.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We ran this cell through full charge and discharge cycles on a VivoBook S400 unit. The BMS accepted the pack without fault codes, the charge controller stepped through its CC\/CV stages cleanly, and the fuel gauge IC registered the cell correctly within two full cycles.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003ePost-install discharge cycle on VivoBook S300 \/ S400:\u003c\/strong\u003e\n    After fitting this battery, run one full discharge down to hibernate cutoff, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears on the first boot after any cell swap.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eBIOS reporting poor battery health immediately after fitting a new cell\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe VivoBook BIOS stores battery health data in EEPROM on the old pack. When a new cell is fitted, the BIOS reads zero cycle history and flags the pack as degraded or unknown. This is not a fault with the replacement cell — it is the BIOS comparing fresh EEPROM data against its stored baseline. Run one complete discharge-to-hibernate followed by a full uninterrupted charge. After two to three cycles, the fuel gauge IC recalibrates and the BIOS health status updates to reflect the actual cell condition.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eVivoBook S300 \/ S400 shutting down at 20–30% charge shown\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThis happens when the fuel gauge IC is still calibrated against the old, degraded cell's voltage curve. The display shows 25% remaining while the actual cell voltage has already dropped below the BMS cutoff threshold under combined CPU and display load. The laptop cuts power before the OS can trigger a graceful shutdown. Run two full discharge-to-hibernate cycles — the fuel gauge IC maps the new cell's voltage curve and the reported percentage aligns with the real state of charge, typically resolving the early cutoff after cycle two.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43409789091930,"sku":"BWCS-AUX402NB-1","price":105.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43409789124698,"sku":"BWCS-AUX402NB-2","price":121.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43409789157466,"sku":"BWCS-AUX402NB-3","price":131.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-AUX402NB-1.webp?v=1779580872","url":"https:\/\/batteryweb.com\/products\/asus-vivobook-s300-replacement-battery-111v-4000mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}