{"product_id":"myphone-8870-replacement-battery-37v-1050mah-li-ion","title":"MyPhone MP-S-K 8870 Replacement Battery 3.7V 1050mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eMyPhone 8870 — 3.7V Li-ion Replacement Battery (MP-S-K)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.7V, 1050mAh Li-ion replacement battery for the MyPhone 8870 smartphone. Part number MP-S-K matches the original cell specification. It fits directly into the 8870 battery bay at 59.90 x 39.90 x 4.50mm.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eMyPhone 8870 fit:\u003c\/strong\u003e\n    The 8870 uses a slim single-cell Li-ion pack at 3.7V nominal. This replacement matches that voltage rail and physical footprint, so the connector seats correctly and the charge IC receives the expected cell parameters.\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 under load typical of smartphone modem and display draw. The BMS held cutoff correctly at both ends of the voltage window without triggering false low-battery shutdowns.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration on first use:\u003c\/strong\u003e\n    On first install, disable any fast-charge option and run one full discharge-to-charge cycle at standard current. This lets the fuel gauge IC 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 MyPhone 8870 reports wrong battery percentage after a cell swap\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThe 8870's fuel gauge IC stores a learned discharge curve from the original cell. When a new cell goes in, that stored curve no longer matches the actual cell chemistry and internal resistance. The gauge reads voltage and estimates percentage against old data, so it can show 40% while the cell is actually near depletion. One full discharge down to automatic shutdown followed by an uninterrupted charge to 100% forces the coulomb counter to rebuild its reference points against the new cell.\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 cell voltage drops sharply under the combined load of the modem radio, backlight, and active apps — a voltage cliff the fuel gauge did not predict. The phone's protection circuit cuts power before the percentage display reaches zero. A fresh cell with an uncalibrated gauge is most vulnerable in the first few cycles. Run the first discharge under light use, let the device shut off naturally, then charge fully to 4.2V — the gauge recalibrates and the cliff effect typically disappears by the third cycle.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43392097321050,"sku":"BWCS-MYP887SL-1","price":22.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43392097353818,"sku":"BWCS-MYP887SL-2","price":25.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43392097386586,"sku":"BWCS-MYP887SL-3","price":27.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-MYP887SL-1.webp?v=1779143764","url":"https:\/\/batteryweb.com\/products\/myphone-8870-replacement-battery-37v-1050mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}