{"product_id":"xiaomi-mi-9t-replacement-battery-385v-4000mah-li-polymer","title":"Xiaomi Mi 9T Replacement Battery BM4G 3.85V 4000mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eXiaomi Mi 9T \/ Mi 9T Pro — 3.85V Li-Polymer Replacement Battery (BM4G)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.85V, 4000mAh (15.4Wh) lithium-polymer cell for the Xiaomi Mi 9T and Mi 9T Pro. OEM part number BM4G. It fits the pop-up camera variants of the Mi 9T lineup — both share the same battery bay, connector, and BMS handshake protocol.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eMi 9T and Mi 9T Pro compatibility:\u003c\/strong\u003e\n    Both models run the same battery bay geometry and use the same four-pin connector with identical BMS communication. One cell fits both — no hardware modification needed.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this cell through full charge and discharge on a Mi 9T unit. The BMS accepted the cell on first connection, charge termination triggered correctly at 4.4V, and no thermal flags appeared during the fast-charge phase.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFirst-cycle fast charge protocol:\u003c\/strong\u003e\n    On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate its coulomb counter against the new cell's discharge curve before high-current 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\"\u003eSudden shutdown at 20–30% on the BM4G replacement cell\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThis happens when the fuel gauge IC is still calibrated to the old cell's discharge curve. A fresh cell has a steeper voltage cliff under modem or display load — the phone reads 25% but the actual cell voltage drops below the BMS cutoff threshold under that load spike. The BMS trips and the phone shuts down hard. One full discharge-charge cycle without fast charging corrects the coulomb counter and the shutdowns stop.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003ePhone not powering on after the BM4G sat in storage\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eLithium-polymer cells stored below approximately 2.5V per cell trigger BMS lockout — the protection circuit opens and blocks current flow to prevent damage. A standard charger cannot restart the phone in this state. Connect the phone to a 5V\/1A USB-A charger — not a fast charger — and leave it for 20–30 minutes without attempting to power on. The charge IC delivers a low-current trickle that brings the cell above the BMS re-enable threshold, typically around 2.9V, after which normal charging resumes.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43391789563994,"sku":"BWCS-MUT910SL-1","price":38.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43391789596762,"sku":"BWCS-MUT910SL-2","price":45.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43391789629530,"sku":"BWCS-MUT910SL-3","price":49.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-MUT910SL-1.webp?v=1779142036","url":"https:\/\/batteryweb.com\/products\/xiaomi-mi-9t-replacement-battery-385v-4000mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}