{"product_id":"amazon-kindle-fire-hd-8th-replacement-battery-38v-4750mah-li-polymer","title":"Amazon Kindle Fire HD 8th ST33 Replacement Battery 3.8V 4750mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eAmazon Kindle Fire HD 8th Generation — 3.8V Li-Polymer Replacement Battery (ST33)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 3.8V, 4750mAh lithium-polymer cell replaces part number ST33 in the Amazon Kindle Fire HD 8th generation tablet, covering device variants K72LL3 and K72LL4. It restores power to tablets where the original cell no longer holds a charge or fails to power on. Capacity matches OEM spec at 18.05Wh.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eK72LL3 and K72LL4 compatibility:\u003c\/strong\u003e\n    Both variants share the same 3.8V power rail, connector pinout, and charge IC handshake, so one cell covers the full 8th generation Fire HD 8 lineup 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 a Fire HD 8 unit. The BMS accepted the charge IC handshake on the first cycle and held voltage within spec across display-on and idle states.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration after swap:\u003c\/strong\u003e\n    After installing this battery, run the tablet from 100% down to automatic shutoff without interruption, then charge uninterrupted back to 100%. This resets the fuel gauge IC against the new cell and corrects the inaccurate percentage readings that typically appear after a battery replacement.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eKindle Fire HD 8 shutting down at 15–25% remaining\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThe Fire HD 8 runs a combined load from its display backlight and WiFi radio simultaneously. When the battery cell ages, voltage drops sharply under this combined draw — the BMS reads the sag as a low-voltage fault and triggers shutdown before the percentage counter reaches zero. A new cell with full capacity holds voltage flatter under load, eliminating early cutoffs. After fitting this replacement, complete one full discharge cycle so the fuel gauge IC maps the actual voltage curve of the new cell.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eFire HD 8 showing wrong battery percentage after replacement\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe fuel gauge IC on the Fire HD 8 stores a learned voltage profile of the old, degraded cell. When a new cell goes in, that stored profile no longer matches reality, so the percentage reading jumps, drops, or stalls. This is not a fault with the replacement battery — it is a calibration mismatch. Fix it by discharging fully to automatic shutoff, then charging uninterrupted to 100%; the gauge IC resets its reference at 4.2V full charge and recalibrates from there.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43425834139738,"sku":"BWCS-ABD724SL-1","price":33.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43425834172506,"sku":"BWCS-ABD724SL-2","price":38.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43425834205274,"sku":"BWCS-ABD724SL-3","price":42.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-ABD724SL-1.webp?v=1779929903","url":"https:\/\/batteryweb.com\/products\/amazon-kindle-fire-hd-8th-replacement-battery-38v-4750mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}