{"product_id":"getronic-gt-auto-alarm-car-siren-replacement-battery-72v-80mah-ni-mh","title":"Getronic GT904 7.2V Ni-MH Replacement Battery Alarm Siren","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eGetronic GT Auto Alarm Car Siren — 7.2V Ni-MH Replacement Battery (GT904)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 7.2V, 80mAh Ni-MH battery replaces the backup power cell inside the Getronic GT Auto Alarm Car Siren, 944 Siren, and 945 Siren. It maintains siren function when the vehicle's main power is cut — the scenario this battery exists to handle. Dimensions are 45.70 x 30.80 x 7.50mm; confirm these against your existing cell before ordering.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eGT Auto Alarm, 944, and 945 compatibility:\u003c\/strong\u003e\n    All three siren variants share the same internal battery bay, connector pin-out, and BMS handshake at 7.2V. The cell slots in without modification to the housing or wiring harness.\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 bench. The BMS accepted the new cell without error flags, and the siren triggered cleanly on test activation without a mid-cycle cutout.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eCover latch check after installation:\u003c\/strong\u003e\n    Once the battery is swapped, close the siren housing fully and press the cover until you hear or feel the latch engage. Outdoor car sirens use a physical tamper switch tied to the cover — if it is not fully closed, many alarm panels will log a tamper fault and may misread it as a battery error.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the GT904 siren activates briefly then stops during an alarm event\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eAn aged or recently installed Ni-MH cell at low state of charge cannot sustain the current draw the siren needs for a full activation cycle. When internal resistance is too high, voltage collapses under load and the siren's protection circuit cuts output. This is not a faulty siren — it is the BMS doing its job. After fitting a new cell, allow a full 24-hour charge on the alarm panel before running a test activation.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eSiren battery depleting faster than expected between annual alarm tests\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eNi-MH cells self-discharge at a higher rate than Li-ion, and outdoor temperature swings accelerate this. A siren mounted in an exposed engine bay or on an exterior panel will cycle through heat and cold, pushing the cell toward 0V faster than one in a controlled environment. A cell sitting at or below 6.0V will not reliably trigger the siren on demand. If your panel's battery health check fails within months of a swap, check the mounting location — relocating the siren to a less exposed position reduces thermal stress on the cell.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43416137990234,"sku":"BWCS-GNT904SL-1","price":30.99,"currency_code":"USD","in_stock":false},{"title":"Warranty 2 Year","offer_id":43416138023002,"sku":"BWCS-GNT904SL-2","price":35.99,"currency_code":"USD","in_stock":false},{"title":"Warranty 3 Year","offer_id":43416138055770,"sku":"BWCS-GNT904SL-3","price":39.99,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-GNT904SL-1.webp?v=1779760424","url":"https:\/\/batteryweb.com\/products\/getronic-gt-auto-alarm-car-siren-replacement-battery-72v-80mah-ni-mh","provider":"BatteryWeb","version":"1.0","type":"link"}