{"product_id":"nokia-8820-replacement-battery-37v-750mah-li-ion","title":"Nokia 8820 BL-6U Replacement Battery 3.7V 750mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eNokia 8820 \/ Erdos — 3.7V Li-ion Replacement Battery (BL-6U)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThe BL-6U is a 3.7V, 750mAh lithium-ion cell that fits the Nokia 8820 and Erdos mobile phones. It slots directly into the original battery bay using the same contact layout as the factory cell. Capacity figures here come from the product specification — 750mAh \/ 2.78Wh.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003e8820 and Erdos compatibility:\u003c\/strong\u003e\n    Both handsets run off the same BL-6U footprint and 3.7V nominal rail. The contact spacing, connector polarity, and BMS communication lines match across both models, so the same cell fits 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 discharge cycles on the 8820 platform. The onboard BMS accepted charge current without tripping, and the protection circuit responded correctly to low-voltage cutoff at the expected threshold.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration after swap:\u003c\/strong\u003e\n    After fitting this cell, run one full discharge to automatic shutdown followed by a complete uninterrupted charge before enabling any battery-saving or fast-charge modes. This gives the phone's coulomb counter a clean reference curve against the new cell before it starts making load predictions.\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 8820 reports wrong battery percentage after a cell swap\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThe 8820 uses a fuel gauge IC that builds its percentage estimate from a stored discharge curve tied to the original cell's impedance profile. When a new cell goes in, that stored curve no longer matches the actual electrochemistry in the new pack. The IC keeps calculating against old data until it has a fresh full cycle to work from. One complete drain-to-shutdown followed by a full charge resets the reference point and brings the readout back into alignment.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eSudden shutdown at 20–30% remaining on the new cell\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThis happens when the cell voltage drops below the modem or display's minimum operating threshold under load, even though the fuel gauge still shows charge remaining. A fresh cell with an uncalibrated coulomb counter can misread state-of-charge by 15–25% in early cycles. The phone cuts out not because the battery is faulty, but because actual terminal voltage has hit the cutoff floor before the gauge catches up. After two full discharge-charge cycles, the gauge recalibrates and the shutdown point moves back to below 10%.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43405121912922,"sku":"BWCS-NK6USL-1","price":22.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43405121945690,"sku":"BWCS-NK6USL-2","price":25.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43405121978458,"sku":"BWCS-NK6USL-3","price":27.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-NK6USL-1.webp?v=1779369992","url":"https:\/\/batteryweb.com\/products\/nokia-8820-replacement-battery-37v-750mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}