{"product_id":"samsung-watch-5-40mm-replacement-battery-388v-270mah-li-polymer","title":"Samsung Watch 5 40mm EB-BR900ABY Replacement Battery 3.88V 270mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eSamsung Watch 5 40mm — 3.88V Li-Polymer Replacement Battery (EB-BR900ABY)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.88V, 270mAh Li-Polymer cell that replaces the original battery in the Samsung Watch 5 40mm smartwatch. It fits SM-R900 and SM-R905 variants. Swap it in when the original cell degrades, fails to hold charge, or can no longer power the watch through a normal day.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eSM-R900 and SM-R905 fit:\u003c\/strong\u003e\n    Both variants share the same battery bay dimensions, connector pinout, and BMS handshake protocol. The 21.50 x 19.80 x 5.10mm cell geometry matches the chassis cavity exactly, so the flex connector seats without force.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We ran the cell through charge acceptance and BMS communication checks on SM-R900 hardware. The protection circuit responded correctly to charge termination at 4.35V and tripped low-voltage cutoff at the expected threshold.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge reset after swap:\u003c\/strong\u003e\n    After fitting this cell, place the watch on its magnetic charger immediately and charge it to 100% before wearing it. The MAX77729 fuel gauge IC loses its reference point when the cell is disconnected — it cannot re-calibrate without a full charge cycle from near-zero following a cell swap. Skipping this step causes the percentage to read incorrectly for days.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the Watch 5 40mm battery degrades faster with always-on display and continuous HR monitoring active\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThe Watch 5 40mm packs a 270mAh cell into a small chassis, leaving little headroom for high-draw feature combinations. Always-on display keeps the AMOLED panel energised continuously, pulling a steady load the cell was not sized to absorb all day. Add continuous heart rate monitoring — which fires the PPG sensor every second — and the combined draw accelerates capacity fade in the original cell within 12 to 18 months of daily use. A fresh cell restores baseline capacity, but the same feature load applies from day one.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWatch not pairing with phone after battery replacement\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eRemoving the battery cuts power to the BLE stack entirely, which terminates the active pairing session stored in the watch's non-volatile memory. The phone retains its side of the bond record, but the watch no longer recognises it as a trusted device after the power interruption. Open the Galaxy Wearable app on the phone, go to Watch Settings, and select \"Disconnect and remove watch\" to clear the stale bond. Re-pair from scratch — the process takes under two minutes and restores full connectivity.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43416158568538,"sku":"BWCS-SMR900SH-1","price":33.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43416158601306,"sku":"BWCS-SMR900SH-2","price":39.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43416158634074,"sku":"BWCS-SMR900SH-3","price":43.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-SMR900SH-1.webp?v=1779760522","url":"https:\/\/batteryweb.com\/products\/samsung-watch-5-40mm-replacement-battery-388v-270mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}