{"product_id":"coolpad-legacy-replacement-battery-385v-3900mah-li-polymer","title":"Coolpad Legacy CPLD-428 Replacement Battery 3.85V 3900mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eCoolpad Legacy \/ CP3705AS — 3.85V Li-Polymer Replacement Battery (CPLD-428)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3900mAh Li-Polymer cell at 3.85V, built to fit the Coolpad Legacy (CP3705AS). It replaces the original CPLD-428 when the factory cell has degraded through repeated charge cycles. Voltage and capacity match the original spec: 3.85V, 3900mAh, 15.02Wh.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eLegacy \/ CP3705AS platform fit:\u003c\/strong\u003e\n    Both model variants share the same battery bay dimensions (88.24 × 66.30 × 4.25mm), connector pinout, and BMS handshake — so a single CPLD-428 cell covers the full Legacy lineup without modification.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We ran this cell through charge and load cycles on a CP3705AS unit. The BMS accepted charge current without tripping, voltage held steady under screen-on and modem load, and cutoff triggered cleanly at low-cell threshold.\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 for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate against the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell — preventing erratic percentage readings early on.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the Coolpad Legacy reports wrong battery percentage after a cell swap\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe Legacy uses a coulomb-counter fuel gauge IC that builds its charge model against the original cell's capacity and internal resistance profile. When you fit a new cell, the IC is still running the old model. Until it completes a full discharge-charge cycle, the percentage display can read high or low by 10–20%. One full cycle — discharge to automatic shutdown, charge to 100% without interruption — resets the learned curve and brings the readout back in line.\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 yet mapped the new cell's voltage cliff — the point where cell voltage drops sharply under modem or display load. The phone thinks it has charge left, but the cell voltage collapses below the BMS cutoff threshold under real load. The fix is the same full recalibration cycle: let the phone discharge to shutdown naturally, then charge uninterrupted to 100%. After one cycle the IC learns where the actual voltage floor sits and shuts down at the correct percentage.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43391991087194,"sku":"BWCS-CPL370SL-1","price":26.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43391991119962,"sku":"BWCS-CPL370SL-2","price":29.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43391991152730,"sku":"BWCS-CPL370SL-3","price":32.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-CPL370SL-1.webp?v=1779142762","url":"https:\/\/batteryweb.com\/products\/coolpad-legacy-replacement-battery-385v-3900mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}