{"product_id":"msi-x-slim-replacement-battery-148v-4400mah-li-polymer","title":"MSI X-Slim BTY-S31 Replacement Battery 14.8V 4400mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eMSI X-Slim X320 \/ X340 — 14.8V Li-Polymer Replacement Battery (BTY-S31)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 14.8V, 4400mAh (65.12Wh) lithium-polymer replacement battery for MSI X-Slim series notebooks. It covers the X320, X320-037US, X340, and related X-Slim variants. OEM part numbers BTY-S31, BTY-S32, and 925T2950F all cross to this cell.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eX-Slim series fit:\u003c\/strong\u003e\n    The X320 and X340 share the same 14.8V four-cell Li-Polymer architecture, connector pinout, and BMS handshake protocol — which is why a single cell covers the full range. The BMS in these models reads cell voltage across all four cells before allowing charge current to flow.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We ran this cell on an X320 and monitored BMS communication through the SMBus lines. Charge acceptance was clean from 0% to 100%, and the protection circuit tripped correctly at both the low-voltage floor and the 16.8V charge ceiling.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFirst-cycle reset on X-Slim:\u003c\/strong\u003e\n    After fitting this cell, discharge the laptop fully to hibernate-cutoff, then charge uninterrupted to 100%. This forces the BIOS battery learn cycle to recalibrate against the new cell chemistry and clears the false \"poor 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\"\u003eBIOS reporting battery health as poor after fitting a new cell\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThe X-Slim BIOS reads EEPROM data written by the original cell to establish a health baseline. When a new cell goes in, that EEPROM data no longer matches actual cell capacity, so the BIOS flags it as degraded. This is not a fault with the replacement cell — it is a calibration mismatch. Running one full discharge-to-hibernate followed by a continuous charge to 100% prompts the BIOS to rewrite its baseline. After two to three full cycles, the health indicator normalises.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eLaptop shuts down at 20–30% charge shown on the gauge\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThis happens when the fuel gauge IC has not yet calibrated to the new cell's actual voltage curve. The gauge maps percentage to voltage using data from the previous cell, so it misjudges the remaining charge floor. Under full CPU and display load, voltage drops faster than the uncalibrated gauge expects, and the system hits the low-voltage cutoff before the displayed percentage reaches zero. Run two complete discharge-to-hibernate and full-charge cycles without interruption. By the third cycle, the fuel gauge IC re-maps its curve to the new cell and the shutdowns stop.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43410821611610,"sku":"BWCS-MSX360HB-1","price":143.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43410821644378,"sku":"BWCS-MSX360HB-2","price":166.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43410821677146,"sku":"BWCS-MSX360HB-3","price":183.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-MSX360HB-1.webp?v=1779581258","url":"https:\/\/batteryweb.com\/products\/msi-x-slim-replacement-battery-148v-4400mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}