{"product_id":"foxlink-replacement-battery-108v-3400mah-li-ion","title":"FOXLINK FLK644A Cable Modem Replacement Battery 10.8V 3400mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eFOXLINK FLK644A — 10.8V Li-ion Replacement Battery\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 10.8V, 3400mAh Li-ion replacement battery for the FOXLINK FLK644A cable modem backup unit. It restores the modem's ability to stay powered during outages, keeping your internet connection and VoIP line active when mains power drops. Capacity is 36.72Wh, matching the original cell specification.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eCable modem backup platform:\u003c\/strong\u003e\n    Cable modems in the CPB013RX category share a 10.8V three-cell battery architecture with a common connector and BMS handshake that the modem firmware polls on boot. Any voltage mismatch or failed handshake causes the modem to reject the battery outright rather than charge it.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We ran this cell through the modem's BMS handshake sequence and confirmed the firmware acknowledged the battery within the first boot cycle. The protection circuit responded correctly to both charge and discharge thresholds without triggering a fault code.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFirst-charge requirement after installation:\u003c\/strong\u003e\n    Cable modem firmware will not activate backup power until the battery reports a full charge state. Connect the modem to mains power and allow at least four hours of uninterrupted charging before testing backup function — cutting this short means the modem treats the battery as unavailable.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eModem showing battery error after installation\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eWhen a new cell is installed, the modem firmware runs a battery acceptance sequence that can take up to 24 hours. During that window, the modem may display a battery fault LED or error code even though the battery is physically connected and charging correctly. This is a firmware timing behaviour, not a defective cell. Leave the modem on mains power and the error will clear once the firmware completes its validation cycle.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eVoIP calls dropping during power outage while internet stays up\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eData throughput and VoIP telephony draw different sustained power loads from the backup battery. During an outage, the modem allocates battery output to maintain the DOCSIS data channel first — VoIP requires a higher, sustained current draw that a partially charged or degraded cell cannot support. If calls drop but browsing continues, the battery has not completed a full charge cycle. Charge to 100% on mains power, confirm the battery LED is solid, then retest VoIP during a simulated outage.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43333524947034,"sku":"BWCS-CPB013RX-1","price":59.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43333524979802,"sku":"BWCS-CPB013RX-2","price":70.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43333525012570,"sku":"BWCS-CPB013RX-3","price":77.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-CPB013RX-1.webp?v=1778212933","url":"https:\/\/batteryweb.com\/products\/foxlink-replacement-battery-108v-3400mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}