{"product_id":"clevo-nexoc-b509ii-replacement-battery-111v-4400mah-li-ion","title":"W540BAT-6 Clevo Nexoc B509II Compatible Battery 11.1V 4400mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eClevo Nexoc B509II — 11.1V Li-ion Replacement Battery (W540BAT-6)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is an 11.1V 4400mAh (48.84Wh) Li-ion battery for the Clevo Nexoc B509II and compatible notebooks including the Aquado M1519, W550SU1, and W550TU. It replaces OEM part numbers W540BAT-6, 6-87-W540S-427, and related variants. The connector, cell count, and BMS pin-out match the original specification.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eW550-platform compatibility:\u003c\/strong\u003e\n    The B509II, Aquado M1519, W550SU1, and W550TU all share the same 6-cell battery bay geometry, 11.1V voltage rail, and SMBus BMS handshake — which is why one part number covers all of them. The EEPROM data on this cell is written to match that communication protocol.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this battery through full charge and controlled discharge on a W550-platform machine. The BMS reported cell status correctly over SMBus, charge current tapered normally at the top of the range, and the protection circuit tripped cleanly at the low-voltage threshold.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003ePost-install calibration cycle:\u003c\/strong\u003e\n    After fitting this battery, run the laptop down to hibernate cutoff under normal use, then charge uninterrupted to 100% without interruption. This forces the BIOS battery learn cycle to reset against the new cell chemistry and clears the inaccurate health warning that appears after every 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 Clevo W550 platform stores battery health history in the BIOS independently of the cell itself. When a new battery is installed, the BIOS compares incoming SMBus data against its stored wear profile from the old cell — and flags a mismatch as poor health. This is a BIOS-side EEPROM artefact, not a fault with the replacement cell. Running one full discharge-to-hibernate followed by an uninterrupted charge to 100% triggers the learn cycle and rewrites the stored baseline against the new cell's actual capacity.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eLaptop shuts down abruptly at 20–30% charge shown on screen\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThis happens when a worn cell can no longer sustain voltage under simultaneous CPU and display load — the cell voltage drops below the BMS cutoff threshold before the fuel gauge reaches 0%. A new cell eliminates that voltage cliff because its internal resistance is lower and it can deliver the required current without collapsing. If the same shutdown behaviour appears with a new cell, the fuel gauge IC may need additional calibration cycles to map the new cell's discharge curve accurately. Run two to three full discharge-and-charge cycles and verify the shutdown point moves below 10%.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43409677779034,"sku":"BWCS-CLW540NB-1","price":75.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43409677811802,"sku":"BWCS-CLW540NB-2","price":88.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43409677844570,"sku":"BWCS-CLW540NB-3","price":97.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-CLW540NB-1.webp?v=1779580399","url":"https:\/\/batteryweb.com\/products\/clevo-nexoc-b509ii-replacement-battery-111v-4400mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}