{"product_id":"vivo-s7-5g-replacement-battery-387v-3700mah-li-polymer","title":"Vivo S7 5G Replacement Battery B-N8 3.87V 3700mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eVivo S7 5G \/ V20 Pro 5G — 3.87V Li-Polymer Replacement Battery (B-N8)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3700mAh Li-Polymer cell rated at 3.87V nominal, built to the B-N8 specification. It fits the Vivo S7 5G, V20 Pro 5G, V2020A, and V2020CA. Install it when the original cell can no longer hold a full charge or causes unexpected shutdowns.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eS7 5G and V20 Pro 5G platform fit:\u003c\/strong\u003e\n    These models share the same battery bay geometry, connector pinout, and BMS handshake protocol. The B-N8 cell communicates directly with the fuel gauge IC on both boards without requiring any hardware modification.\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 S7 5G mainboard. The BMS accepted the cell on first connection, charge current ramped normally through CC\/CV stages, and the protection circuit responded correctly to over-discharge cutoff.\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 for one complete discharge-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging begins on an uncalibrated cell — prevents early percentage drift and erratic readings.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the Vivo S7 5G shuts down suddenly at 20–30% after a battery swap\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eA new cell has a slightly different internal resistance profile than the degraded one it replaced. The fuel gauge IC still holds the old discharge curve in its coulomb counter, so it reports 25% remaining while the actual cell voltage is already near the low-load cliff. Under modem or display load, voltage drops sharply, hits the hardware cutoff threshold, and the phone shuts off. One full discharge-charge cycle without fast charging forces the fuel gauge IC to relearn the new curve. After that cycle, percentage readings stabilise and the premature shutdown stops.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eUSB-PD or Vivo fast charge not triggering on the first cycle after replacement\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eAfter fitting a new B-N8 cell, some users see the phone fall back to standard 5W charging even when using the original fast charger. This happens because the charge IC runs a brief handshake with the BMS on every new cell connection, and on the first cycle it defaults to slow charge as a precaution until cell parameters are confirmed. Disconnect the charger, reboot the phone, then reconnect. If fast charge still does not trigger, complete one full slow charge cycle — the charge IC will accept the higher current protocol on the next session once the BMS handshake completes successfully.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43391889997914,"sku":"BWCS-BKS700SL-1","price":26.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43391890030682,"sku":"BWCS-BKS700SL-2","price":29.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43391890063450,"sku":"BWCS-BKS700SL-3","price":32.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-BKS700SL-1.webp?v=1779142540","url":"https:\/\/batteryweb.com\/products\/vivo-s7-5g-replacement-battery-387v-3700mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}