{"product_id":"lg-x440-replacement-battery-385v-3900mah-li-polymer","title":"LG X440 Replacement Battery 3.85V 3900mAh LG4000STCL02","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eLG X440 \/ W30 Plus — 3.85V Li-Polymer Replacement Battery (LG4000STCL02)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.85V, 3900mAh Li-Polymer cell replacing OEM part LG4000STCL02. It fits the LG X440, LMX440IM, W30 Plus, and W30 2019 smartphones. The cell dimensions are 87.40 × 66.70 × 3.80mm — verify your original before installing.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eX440 and W30 series compatibility:\u003c\/strong\u003e\n    These models share the same battery footprint, connector pinout, and BMS handshake protocol. The fuel gauge IC on each device reads the same coulomb counter registers, so the same cell works across all listed variants without firmware conflicts.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this cell on an LMX440IM under mixed screen-on and modem-active load. The BMS held the protection threshold correctly and did not trigger false undervoltage cutoff during the first three cycles.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration on first use:\u003c\/strong\u003e\n    On first use after installation, disable fast charging and run one complete discharge-charge cycle at standard rate. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging begins on an uncalibrated cell.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eSudden shutdown at 20–30% on the replacement cell\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThis is a voltage cliff issue, not a capacity fault. Under peak modem or display load, a fresh cell with an uncalibrated fuel gauge can sag below the BMS protection threshold before the OS reads 0%. The phone shuts down because the BMS trips, even though the percentage indicator still shows charge remaining. One full discharge-charge cycle at standard rate realigns the coulomb counter to the new cell's actual voltage curve. After that cycle, shutdowns at 20–30% should stop — if they continue, verify cell voltage under load sits above 3.4V mid-discharge.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eOS reporting wrong battery percentage after cell swap\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe fuel gauge IC stores a learned discharge model from the original cell. After a swap, it applies that old curve to the new cell, producing percentage readings that jump, stall, or report full charge too early. The fix is a single full discharge to approximately 3.0V followed by an uninterrupted charge to 100% at standard rate — no fast charging during this cycle. That forces the coulomb counter to rewrite its reference table against the new cell. Most LG devices recalibrate within one cycle; erratic readings that persist past two cycles usually indicate a firmware battery stats reset is also needed in the device's service menu.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43391879544922,"sku":"BWCS-LKX440SL-1","price":26.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43391879577690,"sku":"BWCS-LKX440SL-2","price":30.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43391879610458,"sku":"BWCS-LKX440SL-3","price":33.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-LKX440SL-1.webp?v=1779142479","url":"https:\/\/batteryweb.com\/products\/lg-x440-replacement-battery-385v-3900mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}