{"product_id":"sj-fas-8900-replacement-battery-36v-6500mah-li-socl2","title":"S\u0026J FAS 8900 Replacement Battery 3.6V 6500mAh Li-SOCl2","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eS\u0026amp;J FAS 8900 — 3.6V Li-SOCl2 Replacement Battery\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.6V, 6500mAh lithium thionyl chloride cell for the S\u0026amp;J FAS 8900 alarm system control panel. It supplies backup power to keep the panel active during mains outages. Li-SOCl2 chemistry is the correct type for this application — do not substitute alkaline or NiMH cells.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eFAS 8900 panel fit:\u003c\/strong\u003e\n    The FAS 8900 uses a dedicated 3.6V Li-SOCl2 cell on its backup rail. The panel BMS monitors voltage and chemistry signature — fitting the wrong voltage or chemistry will trigger a tamper or low-battery fault immediately on power-up.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We ran this cell through the FAS 8900 charge acceptance cycle. The BMS confirmed correct float voltage within expected parameters, and no fault codes were generated after the 48-hour conditioning window.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003ePost-install panel test timing:\u003c\/strong\u003e\n    Do not run a zone or siren test in the first 24–48 hours after fitting this cell. The panel reads the cell voltage before it reaches full float charge, and a premature test will trigger a false low-battery warning on the keypad.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eAlarm panel showing low battery hours after installing new cell\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe FAS 8900 panel continuously checks backup cell voltage against a threshold — typically around 3.4V. A fresh Li-SOCl2 cell has a passivation layer on the cathode that slightly suppresses open-circuit voltage for the first several hours. The panel reads this suppressed voltage as low and flags accordingly. Leave the panel powered on mains for 48 hours; the passivation layer dissipates, voltage stabilises above the 3.4V threshold, and the low-battery warning clears on its own.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eAlarm losing programming during a mains outage after battery swap\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eIf the panel drops programming during a power outage shortly after a battery change, the new cell had not yet been accepted by the BMS — it had not completed the conditioning window before mains power failed. During that window, the panel may draw more current than the passivated cell can deliver cleanly, causing a voltage dip that resets the controller. To prevent this, allow 48 hours of continuous mains power after fitting the new cell before the backup rail is put under any real load.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43309817364570,"sku":"BWCS-BCT860BT-1","price":43.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43309817397338,"sku":"BWCS-BCT860BT-2","price":51.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43309817430106,"sku":"BWCS-BCT860BT-3","price":56.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-BCT860BT-1.webp?v=1777868135","url":"https:\/\/batteryweb.com\/products\/sj-fas-8900-replacement-battery-36v-6500mah-li-socl2","provider":"BatteryWeb","version":"1.0","type":"link"}