{"product_id":"master-mf01-replacement-battery-37v-900mah-li-ion","title":"Master MF01 Replacement Battery 3.7V 900mAh Li-ion","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eMaster MF01 \/ MF015 \/ MF016 Dual SIM \/ MF021S — 3.7V Li-ion Replacement Battery\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.7V, 900mAh Li-ion cell for Master smartphones including the MF01, MF015, MF016 Dual SIM, and MF021S. It fits phones where the original cell has lost capacity or stopped holding a charge. Dimensions are 53.00 × 34.00 × 4.80mm — confirm against your existing cell before installing.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eMF01 series compatibility:\u003c\/strong\u003e\n    These models share the same physical footprint, connector pinout, and 3.7V nominal voltage rail. The BMS on each accepts the same charge termination voltage, so one cell covers the group without 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 MF01 platform. The BMS accepted the full charge cycle, and the protection circuit tripped correctly at the low-voltage cutoff — no unexpected shutdowns during controlled load testing.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration after swap:\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 actual discharge curve before the OS starts reporting percentages it can trust.\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 problem, not a defective cell. When the screen or modem draws a high current spike, the replacement cell's internal resistance causes a brief voltage drop. If that drop crosses the BMS cutoff threshold — typically around 3.0V — the phone shuts off even though the fuel gauge still shows charge remaining. The fix is one full discharge-charge cycle so the fuel gauge IC recalibrates its curve to the new cell. After calibration, the reported percentage and actual cell voltage align, and the phantom shutdowns stop.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003ePhone reports wrong battery percentage after cell swap\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe OS fuel gauge IC stores a learned discharge curve from the old cell. A new cell with different impedance characteristics makes that stored curve inaccurate, so the percentage reading drifts or jumps. Run one complete discharge down to automatic shutdown, then charge uninterrupted to 100% without fast charging enabled. That single cycle gives the coulomb counter enough data to rebuild an accurate state-of-charge map against the new cell's actual behaviour.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43404206604378,"sku":"BWCS-KMC500SL-1","price":23.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43404206637146,"sku":"BWCS-KMC500SL-2","price":27.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43404206669914,"sku":"BWCS-KMC500SL-3","price":29.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-KMC500SL-1.webp?v=1779369391","url":"https:\/\/batteryweb.com\/products\/master-mf01-replacement-battery-37v-900mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}