{"product_id":"manta-4091s-replacement-battery-37v-1200mah-li-ion","title":"TEL4091S Replacement Battery Nokia 4091S 3.7V 1200mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eManta 4091S \/ 4091S Dual SIM — 3.7V Li-ion Replacement Battery (TEL4091S)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 3.7V, 1200mAh Li-ion cell replaces the original battery in the Nokia 4091S and 4091S Dual SIM mobile phones. It matches the OEM part number TEL4091S and fits the 62.00 × 38.00 × 4.50mm battery bay directly. Install this when the original cell no longer holds a charge through a normal day of calls and messaging.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003e4091S and 4091S Dual SIM compatibility:\u003c\/strong\u003e\n    Both variants share the same battery bay dimensions, connector pinout, and 3.7V nominal rail. The dual SIM model draws slightly more standby current from two active radios, but the cell chemistry and BMS handshake are identical across both.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this cell through full charge and discharge passes on the 4091S platform. The BMS held charge termination correctly at 4.2V and cut off discharge at the low-voltage threshold without triggering false shutdowns mid-cycle.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration on first use:\u003c\/strong\u003e\n    After fitting this cell, disable any fast-charge adapter and run one complete discharge-charge cycle at standard current. This lets the phone's fuel gauge IC map the new cell's discharge curve before it starts reporting accurate percentages.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the 4091S reports wrong battery percentage after a cell swap\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe 4091S uses a fuel gauge IC that stores a learned discharge curve from the original cell. When you install a new cell, that stored curve no longer matches the actual chemistry. The phone reads voltage and maps it to percentage using old data, so it can show 40% when the cell is nearly flat. One full discharge-charge cycle at standard current forces the IC to relearn the curve against the new cell. After that cycle, percentage readings stabilise.\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 cell voltage drops sharply under load — the modem transmitting or the screen at full brightness pulls current the fuel gauge IC didn't predict at that state of charge. The phone reads 25% but the cell voltage collapses below the BMS cutoff threshold under that peak draw. It's not a faulty cell — it's an uncalibrated gauge hitting a real voltage cliff. Run two full discharge-charge cycles and the shutdowns will move to below 10%, which is normal cutoff behaviour for this chemistry.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43405018857562,"sku":"BWCS-NK4UXL-1","price":27.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43405018890330,"sku":"BWCS-NK4UXL-2","price":31.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43405018923098,"sku":"BWCS-NK4UXL-3","price":33.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-NK4UXL-1.webp?v=1779369842","url":"https:\/\/batteryweb.com\/products\/manta-4091s-replacement-battery-37v-1200mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}