{"product_id":"umx-mxc-550-replacement-battery-37v-750mah-li-ion","title":"UMX AB043446LA Samsung SGH-T619 Replacement Battery 3.7V 750mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eUMX MXC-550 — 3.7V Li-ion Replacement Battery (AB043446LA)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 3.7V, 750mAh Li-ion battery replaces the AB043446LA cell in the UMX MXC-550 mobile phone. It fits the original battery bay and connector without modification. Voltage and capacity match the factory specification exactly.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eMXC-550 fit:\u003c\/strong\u003e\n    The MXC-550 uses a single-cell Li-ion pack with a compact footprint — 49.53 × 33.73 × 7.29mm. The AB043446LA part number is the only cell that clears the battery bay depth and mates with the phone's three-pin connector without forcing the back cover.\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 the MXC-550 platform. The BMS accepted charge handshake on first connection, reached 4.2V at full charge, and held the low-voltage cutoff at 3.0V without triggering premature shutdown under screen and modem load.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration after install:\u003c\/strong\u003e\n    On first use, disable any fast-charge accessory and run one complete discharge-to-charge cycle at standard current. This gives the fuel gauge IC time to map 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\"\u003eWhy the MXC-550 reports wrong battery percentage after a cell swap\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThe MXC-550 uses a fuel gauge IC that tracks charge state by learning the cell's discharge curve over repeated cycles. When a new cell goes in, the IC is still calibrated to the old, degraded cell — so its percentage readings are inaccurate from the start. The phone may show 40% remaining and cut off moments later, or sit at 100% far longer than expected. One full discharge down to auto-shutdown followed by a complete charge resets the coulomb counter and brings percentage reporting back in line.\u003c\/p\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 happens when the modem or display draws a brief high-current spike and the cell voltage dips below the BMS cutoff threshold — even though the fuel gauge still shows charge remaining. It is a calibration gap, not a defective cell. The fuel gauge IC has not yet learned the new cell's voltage cliff. Run two full discharge-charge cycles at standard current, and the shutdowns should stop. If the phone still cuts out after two cycles, check that resting cell voltage reads at least 3.7V with a multimeter before reinstalling.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43409459249242,"sku":"BWCS-SMT619SL-1","price":22.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43409459282010,"sku":"BWCS-SMT619SL-2","price":25.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43409459314778,"sku":"BWCS-SMT619SL-3","price":27.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-SMT619SL-1.webp?v=1779579767","url":"https:\/\/batteryweb.com\/products\/umx-mxc-550-replacement-battery-37v-750mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}