{"product_id":"megafon-optima-ms3b-replacement-battery-37v-1300mah-li-ion","title":"MegaFon Optima MS3B Compatible Battery 3.7V 1300mAh Li-ion","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eMegaFon Optima MS3B — 3.7V Li-ion Replacement Battery\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 3.7V 1300mAh Li-ion cell replaces the original battery in the MegaFon Optima MS3B smartphone. It slots into the same battery bay and connects to the same charging IC as the factory unit. Capacity is 1300mAh (4.81Wh), taken from product data — not estimated.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eOptima MS3B fit:\u003c\/strong\u003e\n    The MS3B runs a single-cell 3.7V architecture with a shared BMS connector tied directly to the phone's fuel gauge IC. Any cell outside this voltage window causes immediate BMS rejection at power-on. This cell matches that window exactly.\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 MS3B platform. The BMS accepted the cell without tripping, and the charge IC held steady through a full cycle at rated current without thermal flags.\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 pushes into an uncalibrated cell — preventing erratic percentage readings from the first hour.\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 replacement cell\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThis is a voltage cliff issue, not a capacity fault. When the modem or display draws a current spike, the cell voltage drops below the BMS cutoff threshold — even though the reported percentage still reads 20–30%. The fuel gauge IC is reading state-of-charge from an old calibration curve, so its estimate no longer matches the real cell voltage. One full discharge-charge cycle lets the coulomb counter relearn the actual cutoff point on the new cell — after that, the shutdown threshold aligns with real voltage, typically around 3.4V under load.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003ePhone not powering on after battery sat discharged in storage\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eIf the cell voltage drops below approximately 2.5V during storage, the BMS enters lockout mode to prevent damage to the cell. The phone will show no charge indicator and will not respond to a short press of the power button. Connect to a wall charger — not a PC USB port — and leave it for at least 20 minutes before attempting to power on. Wall chargers deliver enough current to push the cell above the BMS re-initialisation threshold, typically around 2.9V, which unlocks normal charging.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43405054738522,"sku":"BWCS-OT990SL-1","price":23.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43405054771290,"sku":"BWCS-OT990SL-2","price":26.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43405054804058,"sku":"BWCS-OT990SL-3","price":28.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-OT990SL-1.webp?v=1779369883","url":"https:\/\/batteryweb.com\/products\/megafon-optima-ms3b-replacement-battery-37v-1300mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}