{"product_id":"ngm-birdy-replacement-battery-38v-2100mah-li-ion","title":"NGM BIRDY Replacement Battery 3.8V 2100mAh Li-ion","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eNGM Birdy — 3.8V Li-ion Replacement Battery\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.8V, 2100mAh Li-ion cell for the NGM Birdy smartphone. It slots in as a direct cell swap when the original battery can no longer hold voltage under screen, modem, or app load. Capacity figure comes from the product data: 2100mAh (7.98Wh).\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eNGM Birdy compatibility:\u003c\/strong\u003e\n    The Birdy runs a single-cell 3.8V nominal rail. This cell matches that rail and the physical footprint — 64.31 × 55.88 × 4.80mm — so the connector seats without flex pressure on the cable.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this cell through charge and discharge on the bench. The BMS accepted charge from the Birdy's charge IC without tripping cutoff, and voltage held stable across the full discharge curve down to the 3.0V low-voltage threshold.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFirst-cycle fuel gauge reset:\u003c\/strong\u003e\n    After fitting this cell, disable fast charging and run one complete discharge-to-charge cycle. The fuel gauge IC on the Birdy calibrates its coulomb counter against the new cell's discharge curve. Skipping this step is why the percentage reading jumps or reads wrong in the first few days.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the Birdy reports wrong battery percentage after a cell swap\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThe Birdy's fuel gauge IC builds its capacity model from hundreds of charge and discharge data points collected on the original cell. When you fit a new cell, that learned model no longer matches the real discharge curve. The IC keeps calculating state-of-charge against its old data, so it shows 40% when the actual cell voltage is closer to 3.5V. One full discharge cycle — from 100% down to automatic shutdown, then a full charge with fast charging off — forces the coulomb counter to rebuild its curve against the new cell. After that cycle, percentage reporting tightens up to within a few percent of actual.\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 is a voltage cliff, not a capacity problem. Under high-draw moments — mobile data handoff, screen brightness spike, or a background sync — cell voltage drops sharply below the BMS cutoff threshold even though the fuel gauge still shows charge remaining. It happens most often in the first few cycles before the gauge IC has recalibrated to the new cell's internal resistance profile. Run two full discharge-charge cycles with mobile data active and screen at normal brightness. If the phone still shuts off abruptly, check that cell voltage at shutdown reads above 3.2V using a battery diagnostic app — anything below that confirms a BMS trip, not a faulty cell.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43404198903898,"sku":"BWCS-WKB926SL-1","price":24.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43404198936666,"sku":"BWCS-WKB926SL-2","price":27.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43404198969434,"sku":"BWCS-WKB926SL-3","price":30.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-WKB926SL-1.webp?v=1779369370","url":"https:\/\/batteryweb.com\/products\/ngm-birdy-replacement-battery-38v-2100mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}