{"product_id":"mwg-401-replacement-battery-37v-1700mah-li-ion","title":"MWG 401 Replacement Battery UBI-4-1300 3.7V 1700mAh Li-ion","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eMWG 401 — 3.7V Li-ion Replacement Battery (UBI-4-1300)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.7V, 1700mAh Li-ion replacement battery for the MWG 401 smartphone. It replaces OEM part number UBI-4-1300 and slots into the same battery bay as the original cell. Use this when the factory battery no longer holds charge or triggers unexpected shutdowns.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eMWG 401 fitment:\u003c\/strong\u003e\n    The 401 uses a single-cell 3.7V nominal Li-ion architecture with a BMS that checks cell voltage at power-on. This replacement matches the connector pinout and voltage profile that BMS handshake expects on boot.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We ran this cell through full charge-discharge cycles on a controlled rig. The BMS accepted the cell without protection-circuit lockout, and charge termination triggered correctly at 4.2V.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration on first use:\u003c\/strong\u003e\n    After installation, disable fast charging and run one full discharge-to-charge cycle before normal use. The fuel gauge IC on the MWG 401 calibrates its coulomb counter against the cell's discharge curve — skipping this step causes erratic percentage readings 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\"\u003eSudden shutdown at 20–30% on the MWG 401 after a cell swap\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThis is a voltage cliff issue, not a capacity defect. Under modem transmission or screen-at-full-brightness load, the new cell's internal resistance causes a sharper voltage drop than the fuel gauge IC predicts from its old lookup table. The phone interprets this drop as a critically low cell and cuts power to protect the hardware. One full discharge-to-shutdown cycle followed by a complete charge resets the coulomb counter and shifts the IC's cutoff mapping to match the new cell's actual discharge curve.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eMWG 401 not powering on after sitting in storage with a flat battery\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eIf the cell discharged below approximately 2.5V in storage, the BMS enters lockout mode and blocks current flow to protect the cell from damage. The phone will not respond to a short press of the power button and may show no charging animation. Connect to a low-current USB charger — not a fast charger — and leave it for 20–30 minutes without attempting to power on. Once the cell climbs back above 3.0V, the BMS releases its lockout and the phone will boot normally.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43405153337434,"sku":"BWCS-UB401XL-1","price":31.99,"currency_code":"USD","in_stock":false},{"title":"Warranty 2 Year","offer_id":43405153370202,"sku":"BWCS-UB401XL-2","price":36.99,"currency_code":"USD","in_stock":false},{"title":"Warranty 3 Year","offer_id":43405153402970,"sku":"BWCS-UB401XL-3","price":40.99,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-UB401XL-big.webp?v=1779370298","url":"https:\/\/batteryweb.com\/products\/mwg-401-replacement-battery-37v-1700mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}