{"product_id":"nokia-5310-replacement-battery-37v-820mah-li-ion","title":"Nokia BL-4CT 5310 Replacement Battery 3.7V 820mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eNokia 5310 \/ 7210 Supernova Series — 3.7V Li-ion Replacement Battery (BL-4CT)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.7V, 820mAh Li-ion replacement battery for the Nokia BL-4CT cell. It fits the Nokia 5310, 6600 Fold, 7210 Supernova, 7310 Supernova, and eight additional models sharing the same form factor. Dimensions are 54.26 × 33.67 × 4.23mm — same as the original cell.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eMulti-model fit across the BL-4CT platform:\u003c\/strong\u003e\n    The 5310, 7210 Supernova, 7310 Supernova, and 6600 Fold all run the same 3.7V single-cell architecture with an identical connector footprint and BMS handshake. One cell covers the full lineup because Nokia standardised the protection circuit interface across these handsets.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this cell on a 5310 and 7210 Supernova unit. The BMS accepted charge without a protection trip, voltage held within 50mV of rated at mid-discharge, and the fuel gauge IC accepted the new cell on the first full cycle.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFirst-cycle fuel gauge reset on the BL-4CT:\u003c\/strong\u003e\n    After fitting this cell, run one full discharge to auto-shutoff, then charge uninterrupted to 100% before normal use. The Nokia fuel gauge IC recalibrates its coulomb counter against the new cell's discharge curve during that first cycle — skipping it causes early percentage jumps.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the Nokia 5310 reports wrong battery percentage after a cell swap\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eNokia's fuel gauge IC stores a discharge curve from the original cell in non-volatile memory. When a new cell goes in, the stored curve no longer matches actual cell chemistry, so the reported percentage drifts — often reading 40% when the phone is close to cutoff voltage. The fix is a full recalibration cycle: discharge completely until the phone shuts itself down, then charge to 100% without interruption. After that single cycle, the coulomb counter maps against the new cell and percentage reporting stabilises.\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 is still reading from the old cell's calibration data and the phone hits the hardware low-voltage cutoff — typically 3.2V on Nokia's BL-4CT BMS — before the OS registers a low battery warning. The cell voltage collapses faster than the uncalibrated counter expects under screen or call load. Run one complete discharge-to-shutoff cycle followed by a full uninterrupted charge. If shutdowns persist after two full cycles, measure resting voltage after shutdown — a healthy cell should read above 3.3V at the hardware cutoff point.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43409488904282,"sku":"BWCS-NK4TSL-1","price":22.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43409488937050,"sku":"BWCS-NK4TSL-2","price":25.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43409488969818,"sku":"BWCS-NK4TSL-3","price":27.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-NK4TSL-1.webp?v=1779579814","url":"https:\/\/batteryweb.com\/products\/nokia-5310-replacement-battery-37v-820mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}