{"product_id":"fitbit-charge-5-replacement-battery-387v-65mah-li-polymer","title":"FitBit Charge 5 Compatible Battery 3.87V 65mAh LSS271617","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eFitBit Charge 5 — 3.87V Li-Polymer Replacement Battery (LSS271617)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.87V, 65mAh Li-Polymer cell for the FitBit Charge 5 fitness tracker. It replaces OEM part LSS271617 — the same cell that powers the AMOLED display, continuous heart rate sensor, and sleep tracking. When the original cell degrades, this swap restores full function without replacing the watch.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eCharge 5 platform fit:\u003c\/strong\u003e\n    The Charge 5 uses a compact Li-Polymer cell at 3.87V nominal to run its sensor array and BLE stack. This cell matches that voltage rail, the 18.30 × 15.20 × 2.60mm footprint, and the flex connector termination on the Charge 5 mainboard.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We ran this cell in a Charge 5 unit and confirmed the fuel gauge IC accepted the new cell, the display initialised, and heart rate tracking resumed after a full charge cycle from near-zero.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003ePost-swap charge requirement:\u003c\/strong\u003e\n    After fitting this cell, place the watch on its magnetic charger immediately and charge to 100% before use. The Charge 5 fuel gauge IC loses its reference point when the cell is swapped — without a full charge cycle from near-zero, it cannot recalibrate and will report inaccurate percentages.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the Charge 5 heart rate sensor shortens new battery life in the first week\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe Charge 5 runs its optical HR sensor in continuous mode by default, pulsing green LEDs and sampling the photodiode every second. A new cell has a slightly different internal impedance than the aged cell it replaced, and the power management IC briefly draws more current while it characterises the new source. This settles within five to seven charge cycles. If drain still seems high after that point, check whether Always-On Display is active in the Fitbit app — that single setting roughly doubles display draw on this platform.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eCharge 5 not pairing to phone after battery swap\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eRemoving the cell cuts power to the BLE stack entirely, which drops the active Bluetooth session and clears the pairing state held in volatile memory. The phone still shows the watch as paired, but the watch no longer recognises the bond. Open the Fitbit app, go to the device settings, tap \"Remove this device,\" then set the Charge 5 up again as new. The sync and notification features restore fully after re-pairing.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43416160862298,"sku":"BWCS-FTC500SL-1","price":26.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43416160895066,"sku":"BWCS-FTC500SL-2","price":30.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43416160927834,"sku":"BWCS-FTC500SL-3","price":33.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-FTC500SL-1.webp?v=1779760505","url":"https:\/\/batteryweb.com\/products\/fitbit-charge-5-replacement-battery-387v-65mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}