{"product_id":"sony-wf-l900-charging-case-replacement-battery-37v-280mah-li-polymer","title":"Sony WF-L900 Charging Case Compatible Battery 3.7V 280mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eSony WF-L900 Charging Case — 3.7V Li-Polymer Replacement Battery (ACE621733)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.7V, 280mAh Li-Polymer replacement battery for the Sony WF-L900 wireless earbud charging case. It slots into the case housing and restores the ability to charge your earbuds away from a wall outlet. When the original cell degrades, the case stops holding charge — this battery replaces it directly using OEM part number ACE621733.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eWF-L900 case fit:\u003c\/strong\u003e\n    The ACE621733 cell matches the physical footprint of the original at 32.00 × 17.40 × 5.70mm. The connector and protection circuit align with the case's charge management board, so the BMS handshake completes 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 full charge and discharge passes and confirmed the protection circuit trips correctly at low-voltage threshold. Charge acceptance and cutoff voltage both matched Sony's spec for this case.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFirst charge after install:\u003c\/strong\u003e\n    Seat the earbuds in the case and plug the case into a USB-C power source for a complete charge cycle before using it untethered. The case charge controller needs a full cycle to recalibrate its state-of-charge reading after a new cell is fitted.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eCase shows full charge but earbuds stop charging after a short time\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eA freshly installed cell often sits at storage voltage — around 3.6V — which the case controller can misread as a full charge. The actual usable capacity is not available until the cell has completed at least one full charge cycle from a wall source. Until that happens, the case may show a full indicator but cut charging to the earbuds early. Run one complete USB-C charge before relying on the case away from a power source.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eCase LED flashes an error or does not respond after battery replacement\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThis happens when the protection circuit on the new cell has not been initialised by the case's charge management board. If the cell arrived in deep-sleep mode, the BMS blocks current flow until it receives a charge pulse. Connect the case to USB-C power for at least 30 seconds — this wakes the cell and allows the board to complete the handshake. If the LED still behaves abnormally, disconnect, wait 10 seconds, and reconnect to trigger a fresh initialisation sequence.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43428103159898,"sku":"BWCS-SWL900SL-1","price":15.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43428103192666,"sku":"BWCS-SWL900SL-2","price":17.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43428103225434,"sku":"BWCS-SWL900SL-3","price":18.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-SWL900SL-1.webp?v=1779579871","url":"https:\/\/batteryweb.com\/products\/sony-wf-l900-charging-case-replacement-battery-37v-280mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}