{"product_id":"nokia-lumia-810-replacement-battery-37v-1400mah-li-ion","title":"Nokia Lumia 810 BP-4W Replacement Battery 3.7V 1400mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eNokia Lumia 810 \/ 822 — 3.7V Li-ion Replacement Battery (BP-4W)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.7V, 1400mAh (5.18Wh) Li-ion battery using OEM part number BP-4W. It fits the Nokia Lumia 810 and Lumia 822 Windows Phone smartphones. Buy this when the original cell no longer holds enough charge for daily use.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eLumia 810 and 822 compatibility:\u003c\/strong\u003e\n    Both models run the same 3.7V battery rail, use an identical physical connector, and communicate with the same fuel gauge IC. BP-4W is the correct part for either handset — the BMS handshake is the same 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 discharge and charge on the Lumia platform. The BMS accepted the cell without fault flags, charge current tapered correctly at end-of-charge, and the fuel gauge IC registered the new cell without intervention.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration on first use:\u003c\/strong\u003e\n    After fitting this cell, disable fast charging and run one complete discharge-to-charge cycle before normal use. The fuel gauge IC was calibrated to your original cell's discharge curve — one full cycle against the new cell lets it rebuild an accurate state-of-charge map.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the Lumia 810 reports wrong battery percentage after a cell swap\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThe Lumia 810 uses a coulomb-counter-based fuel gauge IC that tracks charge in and out of the original cell over its lifetime. When you swap the cell, the IC still holds the old discharge curve in memory. It will report a percentage based on a curve that no longer matches the new cell's chemistry. The fix is one full discharge — down to automatic shutdown — followed by a full uninterrupted charge. After that single cycle, the IC recalibrates 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 cell voltage drops sharply under modem or display load — a voltage cliff the fuel gauge IC did not predict. The OS reads 25% state-of-charge, but actual cell voltage collapses below the 3.0V cutoff the moment current demand spikes. It is not a faulty battery — it is a miscalibrated gauge reading an uncycled cell. Run one full discharge to shutdown, then charge uninterrupted to 100%. After that cycle, the gauge maps the actual voltage cliff and shutdown warnings will fire at the correct percentage.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43404338593882,"sku":"BWCS-NK810SL-1","price":26.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43404338626650,"sku":"BWCS-NK810SL-2","price":29.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43404338659418,"sku":"BWCS-NK810SL-3","price":32.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-NK810SL-1.webp?v=1779369761","url":"https:\/\/batteryweb.com\/products\/nokia-lumia-810-replacement-battery-37v-1400mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}