{"product_id":"lg-cu400-replacement-battery-37v-750mah-li-ion","title":"LG CU400 Replacement Battery 3.7V 750mAh LGIP-A1100","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eLG CU400 \/ CU405 — 3.7V Li-ion Replacement Battery (LGIP-A1100)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.7V, 750mAh Li-ion replacement battery for the LG CU400 and CU405 candybar-style feature phones. It fits directly in place of the original LGIP-A1100 cell. Use it to restore power to a handset where the original battery no longer holds charge through a normal day.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eCU400 and CU405 compatibility:\u003c\/strong\u003e\n    Both models share the same battery bay dimensions, connector pinout, and BMS handshake protocol — one cell covers both. The 54.00 × 34.05 × 5.70mm form factor matches the original housing with no modification needed.\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 the CU400 platform. The BMS accepted the cell without fault flags, and the charge IC reached termination voltage cleanly at 4.2V.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration on first use:\u003c\/strong\u003e\n    After fitting the new cell, run one complete discharge down to automatic shutoff before recharging. This gives the phone's fuel gauge IC a full data set from the new cell's discharge curve — without it, the percentage reading can drift by 15–20% until the IC has reference points at both ends of the voltage range.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the CU400 reports wrong battery percentage after a cell swap\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThe CU400 uses a simple fuel gauge IC that maps voltage to a percentage curve calibrated against the original cell. A new cell has a slightly different internal impedance and discharge slope, so the IC's stored curve no longer matches what it's measuring. The result is percentage readings that jump or stall — commonly sitting at 100% longer than expected, then dropping fast near the bottom. One full discharge-to-shutoff cycle gives the IC new endpoints to anchor against, and readings stabilise after that.\u003c\/p\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 happens when the fuel gauge IC hasn't completed recalibration and the displayed percentage doesn't reflect actual cell voltage. Under load — backlight on, active call — the cell voltage drops faster than the uncalibrated IC expects, and the phone cuts power to protect the cell when voltage falls below the BMS trip threshold. It's not a fault with the replacement cell. Run a full discharge cycle without interruption. After recalibration, the phone's shutoff should align with a cell voltage of approximately 3.4–3.5V rather than triggering early at a misread percentage.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43409435557978,"sku":"BWCS-LCU400SL-1","price":23.99,"currency_code":"USD","in_stock":false},{"title":"Warranty 2 Year","offer_id":43409435590746,"sku":"BWCS-LCU400SL-2","price":26.99,"currency_code":"USD","in_stock":false},{"title":"Warranty 3 Year","offer_id":43409435623514,"sku":"BWCS-LCU400SL-3","price":29.99,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-LCU400SL-big.webp?v=1779579689","url":"https:\/\/batteryweb.com\/products\/lg-cu400-replacement-battery-37v-750mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}