{"product_id":"att-blade-spark-replacement-battery-385v-3100mah-li-polymer","title":"AT\u0026T Blade Spark Z971 Replacement Battery 3.85V 3100mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eAT\u0026amp;T Blade Spark \/ Z971 — 3.85V Li-Polymer Replacement Battery\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 3.85V, 3100mAh Li-Polymer cell replaces the original battery in the AT\u0026amp;T Blade Spark and Z971 smartphones. It fits phones where the original cell has degraded or failed outright. Capacity is rated at 11.94Wh, matching the factory power specification for these models.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eBlade Spark and Z971 fitment:\u003c\/strong\u003e\n    Both phones run on the same battery platform — identical cell dimensions (74.10 × 62.80 × 4.30mm), voltage rail, and connector. One cell covers both models 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 Blade Spark platform. The BMS accepted charge handshake normally, and cell voltage held stable under screen-on and modem-active load without tripping the protection circuit.\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 resuming normal use. The fuel gauge IC is calibrated to the old cell's discharge curve — this first cycle gives it fresh reference data before high-current charging begins on the new cell.\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 Blade Spark after a cell swap\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThis happens when the fuel gauge IC still references the discharge curve of the old, degraded cell. A new cell has a steeper voltage cliff at low charge states — the phone's charge controller reads voltage collapse as a hard cutoff and shuts down before the percentage counter reaches zero. The fix is a full discharge-to-charge cycle with the screen on and mobile data active, which forces the coulomb counter to relearn the curve. After one complete cycle, shutdowns at 20–30% typically stop.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eUSB fast charge not activating after fitting the replacement cell\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eOn the first cycle after a cell swap, the charge IC can refuse to negotiate fast-charge protocol because it sees an unfamiliar BMS response from the new cell. This is a protection behaviour, not a fault. Plug in using the stock cable and charger and let the phone complete a full standard-rate charge first. Once the charge IC logs one complete cycle, fast charging typically re-enables on the next plug-in without any further action needed.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43392081854554,"sku":"BWCS-ZTZ956XL-1","price":26.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43392081887322,"sku":"BWCS-ZTZ956XL-2","price":30.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43392081920090,"sku":"BWCS-ZTZ956XL-3","price":33.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-ZTZ956XL-1.webp?v=1779143639","url":"https:\/\/batteryweb.com\/products\/att-blade-spark-replacement-battery-385v-3100mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}