{"product_id":"asus-k401-replacement-battery-114v-4200mah-li-ion","title":"Asus VivoBook K401 11.4V Replacement Battery B31N1424","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eAsus K401 Series — 11.4V Li-ion Replacement Battery (B31N1424)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is an 11.4V 4200mAh (47.88Wh) Li-ion replacement battery for the Asus VivoBook K401 series, including the K401LB, K401LB5010, and K401LB5200. It replaces OEM part numbers B31N1424 and 0B200-01390000. Fits the compact three-cell configuration used across this ultrabook lineup.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eK401 series compatibility:\u003c\/strong\u003e\n    All models in this lineup share the same 11.4V three-cell architecture, B31N1424 connector pinout, and BMS handshake protocol — the same replacement cell covers the full range without modification.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this cell through charge and discharge on a K401LB unit. The BMS accepted the new cell cleanly, protection thresholds triggered correctly at both ends, and the charge IC reached termination without fault flags.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFirst-cycle calibration on the K401:\u003c\/strong\u003e\n    After fitting, run the laptop on battery until it hibernates from low charge, then charge uninterrupted to 100% without interruption. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on this platform.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the K401 shuts down at 20–30% after a battery swap\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe K401's fuel gauge IC builds a capacity model from the previous cell's discharge curve. A new cell has different internal resistance and a steeper voltage cliff at lower states of charge. The BIOS reads the old curve, sees a voltage drop it doesn't expect, and triggers a protective shutdown before the cell is actually empty. Running two full discharge-to-hibernate and full recharge cycles forces the fuel gauge to rebuild its model against the new cell's actual curve.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eBIOS reporting battery health as poor or unknown after fitting a new cell\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe K401's BIOS reads health status from EEPROM data written during the original cell's service life — cycle count, capacity fade history, and wear flags are all stored there. A new cell doesn't overwrite that data automatically. The \"poor health\" flag reflects the old cell's recorded state, not the physical condition of the replacement. Complete one full learn cycle — discharge to hibernate cutoff, then charge to 100% uninterrupted — and the BIOS will rewrite the health register against the new cell's baseline.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43409728372826,"sku":"BWCS-AUK401NB-1","price":94.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43409728405594,"sku":"BWCS-AUK401NB-2","price":106.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43409728438362,"sku":"BWCS-AUK401NB-3","price":116.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-AUK401NB-1.webp?v=1779580541","url":"https:\/\/batteryweb.com\/products\/asus-k401-replacement-battery-114v-4200mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}