{"product_id":"marmitek-proguard800-siren-replacement-battery-72v-700mah-ni-mh","title":"Marmitek ProGuard800 Siren 7.2V Ni-MH Replacement Battery","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eMarmitek ProGuard800 Siren — 7.2V Ni-MH Replacement Battery (OS826)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 7.2V, 700mAh Ni-MH replacement battery for the Marmitek ProGuard800 Siren (Part No OS826). It restores backup power to the siren unit so it stays operational during mains outages. Fits the ProGuard800 Siren, ProGuard OS826 siren, and the wireless ProGuard alarm panel backup cell slot.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eProGuard800 and OS826 compatibility:\u003c\/strong\u003e\n    These models share the same 7.2V Ni-MH cell format, connector pinout, and charge management circuit. The alarm panel's BMS expects a specific internal resistance profile from this cell count and chemistry — substituting a different voltage or chemistry causes incorrect charge termination or fault codes.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this cell through charge and discharge on the ProGuard platform. The BMS accepted the cell without fault, reached float charge within the expected window, and the panel cleared its low-battery status after the conditioning period.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003ePost-installation charge window:\u003c\/strong\u003e\n    Do not run a zone test or siren test immediately after swapping this cell. The panel requires 24–48 hours on float charge before its BMS reports full capacity. Testing too early will trigger a low-battery warning even from a healthy new cell.\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\n  \u003cp class=\"bpw-desc-p\"\u003eNi-MH cells at rest voltage often read below the panel's acceptance threshold straight out of packaging. The ProGuard BMS does not mark the battery as healthy until it completes a full float charge cycle — typically 24 to 48 hours connected to mains. This is a charge-state check, not a fault with the cell itself. Leave the panel powered on mains and the warning will clear once the cell reaches approximately 8.4–8.5V float.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eSiren not sounding on test after backup battery replacement\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe ProGuard800 Siren includes a short stabilisation delay after a new cell is installed — typically 30 to 60 seconds before it will respond to a trigger. If the test is run within this window, the siren stays silent and the panel may log a siren fault. This is a charge-stabilisation hold built into the siren's local circuit, not a wiring issue. Wait at least 60 seconds after reconnecting the battery before running a walk-test or triggering a zone.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43309831585882,"sku":"BWCS-MOS826BT-1","price":27.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43309831618650,"sku":"BWCS-MOS826BT-2","price":31.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43309831651418,"sku":"BWCS-MOS826BT-3","price":34.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-MOS826BT-1.webp?v=1777868261","url":"https:\/\/batteryweb.com\/products\/marmitek-proguard800-siren-replacement-battery-72v-700mah-ni-mh","provider":"BatteryWeb","version":"1.0","type":"link"}