{"product_id":"asus-bu403ua-replacement-battery-111v-4050mah-li-polymer","title":"Asus BU403UA 11.1V Replacement Battery B31N1507 44.96Wh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eAsus BU403UA \/ PU403UA Series — 11.1V Li-Polymer Replacement Battery (B31N1507)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 11.1V, 4050mAh Li-Polymer battery replaces the OEM cell in the Asus BU403UA, PU403UA, PU403UF, and P5430UA ultrabooks. It matches the original pack's connector, BMS handshake protocol, and physical footprint at 186.46 × 99.10 × 8.00mm. Capacity is rated at 44.96Wh — identical to the factory specification.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eBU403UA and PU403UA platform compatibility:\u003c\/strong\u003e\n    These models share the same 11.1V three-cell Li-Polymer architecture, identical battery bay dimensions, and the same BMS communication protocol over SMBus. One cell fits the entire family 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 BU403UA unit. The BMS accepted the pack without fault codes, balanced all three cells within 10mV at top-of-charge, and held the full 11.1V nominal rail under CPU and display load.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFirst-cycle calibration after install:\u003c\/strong\u003e\n    After fitting this cell, run the laptop on battery until Windows forces hibernate, then charge uninterrupted to 100% without interruption. This single cycle resets the BIOS battery-learn register 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 BU403UA shuts down at 20–30% shown on the fuel gauge\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThe fuel gauge IC on the BU403UA references discharge curves stored from the previous cell. When a new cell is installed, those curves no longer match the actual chemistry, so the gauge underestimates remaining charge. The system triggers a low-battery shutdown before the cell is genuinely depleted. Two to three full discharge-to-hibernate and charge-to-100% cycles recalibrate the gauge IC against the new cell's actual voltage-to-capacity curve. After calibration, the shutdown point drops back to the correct 3% to 5% threshold.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eBIOS reporting battery health as poor or unknown immediately after replacement\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe BIOS pulls health data from EEPROM registers written by the original factory cell. A replacement cell ships with its own EEPROM data, which can read as mismatched or unrecognised on first boot. This is not a fault — it is a data conflict between old and new cell records. Run one full discharge-to-hibernate cycle followed by a full uninterrupted charge to 100%, then reboot. The BIOS battery-learn cycle rewrites the health register against the new cell and the poor-health flag clears.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43409725227098,"sku":"BWCS-AUB403NB-1","price":94.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43409725259866,"sku":"BWCS-AUB403NB-2","price":111.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43409725292634,"sku":"BWCS-AUB403NB-3","price":124.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-AUB403NB-1.webp?v=1779580541","url":"https:\/\/batteryweb.com\/products\/asus-bu403ua-replacement-battery-111v-4050mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}