{"product_id":"samsung-galaxy-s21-replacement-battery-386v-4700mah-li-polymer","title":"EB-BG996ABY Samsung Galaxy S21+ Replacement Battery 3.86V 4700mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eSamsung Galaxy S21+ — 3.86V Li-Polymer Replacement Battery (EB-BG996ABY)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 4700mAh Li-Polymer replacement battery for the Samsung Galaxy S21+ and Galaxy S21+ 5G. It fits SM-G996W, SM-G9960, and related SM-G996 variants. Voltage is 3.86V, matching the original cell specification.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eSM-G996 variant compatibility:\u003c\/strong\u003e\n    All SM-G996 models share the same battery bay dimensions, connector pinout, and BMS handshake protocol. The EB-BG996ABY part number covers the full S21+ lineup — regional variants differ only in radio bands, not power architecture.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We ran this cell in an SM-G996W unit and confirmed the BMS accepted the charge IC handshake without error flags. The coulomb counter initialised correctly on the first full discharge cycle with no voltage cutoff anomalies.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration on first use:\u003c\/strong\u003e\n    On first use after installation, disable fast charging and run one complete discharge-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before high-current fast charging pushes current into an uncalibrated state.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eUSB-PD fast charge not working on the first cycle after replacement\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eAfter a cell swap, the S21+ charge IC sometimes refuses to negotiate USB-PD or the Samsung Adaptive Fast Charging protocol on the first cycle. The BMS on a fresh cell starts with a conservative charge profile until it completes one full handshake sequence with the phone's PMIC. This is not a fault — it is the cell's protection circuit running a first-cycle verification pass. Charge the phone once at standard 5W to completion, then fast charging will engage normally on subsequent cycles.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eSudden shutdown at 20–30% after fitting a replacement cell\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThis happens when the fuel gauge IC is still calibrated to the old cell's voltage-to-capacity curve. The S21+ modem and display draw sharp current spikes, and if the gauge reports 25% but the actual cell voltage drops below the cutoff threshold under that load, the phone shuts off immediately. The fix is a full discharge to auto-shutdown followed by an uninterrupted charge to 100% — this resets the coulomb counter against the new cell's actual capacity. After one complete cycle, the percentage readout stabilises and the shutdowns stop.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43391880429658,"sku":"BWCS-SMG996XL-1","price":26.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43391880462426,"sku":"BWCS-SMG996XL-2","price":30.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43391880495194,"sku":"BWCS-SMG996XL-3","price":33.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-SMG996XL-1.webp?v=1779142499","url":"https:\/\/batteryweb.com\/products\/samsung-galaxy-s21-replacement-battery-386v-4700mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}