{"product_id":"amazon-6581a-replacement-battery-38v-2400mah-li-polymer","title":"Amazon Fire Phone 6581A Replacement Battery 3.8V 2400mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eAmazon Fire Phone — 3.8V Li-Polymer Replacement Battery (26S1003-A)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.8V, 2400mAh Li-Polymer cell that replaces OEM part 26S1003-A in the Amazon Fire Phone (model 6581A), including the 32GB and 64GB variants. It also cross-references 58-000057, 58-000068, and S12-M1-C. If the original cell no longer holds a charge or the phone shuts down unexpectedly, this is the direct swap.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eFire Phone and 6581A tablet compatibility:\u003c\/strong\u003e\n    Both device variants use the same physical cell format, connector pinout, and BMS handshake protocol. Voltage rail is 3.8V nominal across the board, so one cell covers the full compatibility range without hardware 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 Fire Phone platform. The BMS accepted the new cell without rejection errors, and the charge IC ramped current correctly from trickle through CC\/CV phases.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration on first cycle:\u003c\/strong\u003e\n    On first use after installation, run one complete discharge down to automatic shutdown, then charge uninterrupted to 100% before using the device. This lets the coulomb counter IC map the new cell's discharge curve before normal use begins.\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 Fire Phone after a cell swap\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eA new Li-Polymer cell has a slightly different voltage-to-capacity curve than the aged cell it replaces. The Fire Phone's fuel gauge IC was calibrated to the old cell's curve, so it misreads the new cell's state of charge. When the display or modem draws peak current, cell voltage drops below the BMS cutoff threshold even though the OS reports 20–30% remaining. The fix is one full discharge-to-shutdown and uninterrupted recharge cycle — after that, the coulomb counter recalibrates to the new curve and shutdowns stop.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eFire Phone not powering on after the replacement cell sat in storage\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eLi-Polymer cells stored below 2.5V per cell trigger a BMS lockout — the protection circuit disconnects the cell to prevent damage, and the phone shows no response to the power button. Plug into a wall charger using the original cable, not a USB hub or PC port, and leave it for 20–30 minutes before pressing power. Most BMS circuits re-initialise once input voltage from the charger is detected above the lockout threshold. If the screen stays black after 30 minutes on charge, try a second known-good charger before assuming cell failure.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43404268142682,"sku":"BWCS-AMF658SL-1","price":26.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43404268175450,"sku":"BWCS-AMF658SL-2","price":30.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43404268208218,"sku":"BWCS-AMF658SL-3","price":33.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-AMF658SL-1.webp?v=1779369511","url":"https:\/\/batteryweb.com\/products\/amazon-6581a-replacement-battery-38v-2400mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}