{"product_id":"karboon-wind-w4-replacement-battery-38v-1950mah-li-ion","title":"KTSP1950AA Karboon Wind W4 Compatible Battery 3.8V 1950mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eKarboon Wind W4 — 3.8V Li-ion Replacement Battery (KTSP1950AA)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.8V Li-ion cell rated at 1950mAh (7.41Wh), sized to fit the Karboon Wind W4 smartphone. It replaces the original KTSP1950AA unit when the factory cell no longer holds a charge or fails outright. Dimensions are 58.50 × 50.95 × 5.40mm — confirm these against your original before fitting.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eWind W4 fitment:\u003c\/strong\u003e\n    The Wind W4 uses a fixed connector pinout tied to the KTSP1950AA spec. This replacement matches that pinout, voltage rail, and physical footprint so the charge IC recognises the cell without a firmware flag.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled the cell through charge and discharge on a Wind W4 unit and confirmed the BMS accepted the cell, the charge IC hit the correct termination voltage, and no overcurrent faults were logged.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration after fitting:\u003c\/strong\u003e\n    On first use after installation, disable fast charging and run one full discharge-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before the coulomb counter locks in its reference points — skipping this step is the main cause of erratic percentage readings.\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 happens when the fuel gauge IC is still calibrated to the old degraded cell's voltage curve. The new cell's open-circuit voltage drops steeply under modem or screen load at the low end, hitting the hardware cutoff before the OS percentage reaches zero. The phone reads 25% but the cell voltage under load drops below 3.2V, triggering an emergency shutdown. One full unconstrained discharge-charge cycle recalibrates the coulomb counter and eliminates this in most cases.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003ePhone warm near the battery during the first few charges\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eA new Li-ion cell has slightly higher internal impedance than a broken-in cell, so the charge IC dissipates more heat during the constant-current phase. This is normal for the first two to three cycles and does not indicate a fault. Warmth should reduce noticeably by the third full charge. If the phone remains hot to the touch past cycle three, check that no third-party fast-charge adapter is overriding the Wind W4's charge rate.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43404143689818,"sku":"BWCS-BLW410SL-1","price":24.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43404143722586,"sku":"BWCS-BLW410SL-2","price":27.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43404143755354,"sku":"BWCS-BLW410SL-3","price":30.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-BLW410SL-1.webp?v=1779369080","url":"https:\/\/batteryweb.com\/products\/karboon-wind-w4-replacement-battery-38v-1950mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}