{"product_id":"visonic-mcs-740-replacement-battery-36v-4000mah-li-socl2","title":"Visonic MCS-740 Compatible Battery 3.6V 4000mAh Li-SOCl2","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eVisonic MCS-740 \/ SR-740 PG2 — 3.6V Li-SOCl2 Replacement Battery (103-304742-2)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 3.6V, 4000mAh Li-SOCl2 cell replaces the factory battery in the Visonic MCS-740 wireless motion detector and SR-740 PG2 \/ SR 720 PG2 sirens. It matches OEM part numbers 103-304742-2 and 2XER18505M exactly. When the original cell depletes after several years of standby use, this cell restores full operation to the sensor or siren without requiring panel reconfiguration.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eMCS-740, SR-740 PG2, and SR 720 PG2 compatibility:\u003c\/strong\u003e\n    These devices share the same 3.6V primary cell form factor, connector footprint, and BMS handshake. Swapping between them does not require firmware changes or panel re-pairing — the voltage rail is identical across the group.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We ran this cell through the MCS-740 supervision cycle and confirmed the BMS accepted the new cell without triggering a fault flag. The tamper circuit and zone supervision signal both cleared within the expected reporting window.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003ePost-installation panel reporting:\u003c\/strong\u003e\n    Do not run a zone or siren test within the first 24 hours after fitting this cell. Li-SOCl2 cells require a short stabilisation period before the panel reads correct voltage. Running a test too early may cause the panel to log a spurious low-battery event.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the SR-740 PG2 siren stays silent on test after a cell swap\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe SR-740 PG2 holds a deliberate 30–60 second charge stabilisation delay on a fresh primary cell before the siren circuit arms. If you trigger a test immediately after installation, the sounder will not fire — this is normal behaviour, not a wiring fault. The panel may also log \"siren tamper\" or \"siren fault\" during this window. Wait at least one minute after fitting the new cell, then re-arm and run the test from the panel keypad.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003ePanel reports low battery 24 hours after fitting a new cell\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eLi-SOCl2 cells carry a passivation layer that forms during storage. This layer causes the cell to read slightly below nominal voltage on first load — the panel interprets this as a depleted battery. The layer breaks down within 24–48 hours of the cell being active in circuit. If the low-battery alert persists beyond 48 hours, check that the battery contacts are clean and that the device cover is fully closed, then force a supervision poll from the panel at 3.6V nominal to confirm the reading has updated.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43309828505690,"sku":"BWCS-VPX740BT-1","price":57.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43309828538458,"sku":"BWCS-VPX740BT-2","price":67.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43309828571226,"sku":"BWCS-VPX740BT-3","price":75.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-VPX740BT-1.webp?v=1777868465","url":"https:\/\/batteryweb.com\/products\/visonic-mcs-740-replacement-battery-36v-4000mah-li-socl2","provider":"BatteryWeb","version":"1.0","type":"link"}