{"product_id":"bookeen-cybft1f-bk-replacement-battery-37v-2000mah-li-polymer","title":"Bookeen Cybook Muse HD Compatible Battery 3.7V 2000mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eBookeen Cybook Muse HD — 3.7V Li-Polymer Replacement Battery (JL315889PL)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 3.7V, 2000mAh Li-Polymer cell replaces the original JL315889PL battery in the Bookeen Cybook CYBFT1F-BK and Cybook Muse HD e-readers. Both devices share the same battery footprint, connector, and BMS communication protocol. Capacity figure is taken directly from product specification — 7.4Wh total energy.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eCYBFT1F-BK and Muse HD compatibility:\u003c\/strong\u003e\n    Both models run the same internal power rail at 3.7V nominal and use an identical flat Li-Polymer cell with the same physical dimensions and connector pinout. One cell fits both 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 Muse HD unit. The BMS accepted the new cell without fault flags, and the firmware completed its recalibration pass within one full charge cycle.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003ePost-swap charge cycle on Muse HD:\u003c\/strong\u003e\n    After installing this cell, connect via USB and charge completely before reading. The Cybook firmware recalibrates its battery percentage display against a full-charge reference point — skipping this step causes the indicator to read inaccurately for several sessions.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the Cybook Muse HD shows low battery immediately after a new cell\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eReplacement cells ship at storage voltage — typically 3.6V to 3.85V — which sits below the firmware's calibrated full-charge threshold of around 4.2V. The Muse HD reads this as a partially depleted battery, not a fresh one. This is a firmware calibration issue, not a cell defect. Connect to USB power and charge fully before the first use to reset the reference point.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eBattery percentage jumping erratically after swap on CYBFT1F-BK\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe CYBFT1F-BK tracks charge state using a coulomb counter that calibrates itself against the installed cell's actual capacity over the first few cycles. A new cell resets this learned profile, causing the displayed percentage to jump during early use. This settles after two or three complete charge-discharge cycles. If jumps persist beyond three cycles, verify the cell voltage reads at least 4.1V at the top of a full charge.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43360237813850,"sku":"BWCS-BCK100SL-1","price":36.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43360237846618,"sku":"BWCS-BCK100SL-2","price":42.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43360237879386,"sku":"BWCS-BCK100SL-3","price":47.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-BCK100SL-1.webp?v=1778610981","url":"https:\/\/batteryweb.com\/products\/bookeen-cybft1f-bk-replacement-battery-37v-2000mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}