Will a Siren Sound On VISTA-20P Without a Backup Battery?

Yes, a siren will sound on a VISTA-20P without a backup battery, provided that the siren is set up with an auxiliary power supply. If you just have the siren connected directly with the panel, then a backup battery is required, as the siren will draw power from the panel's backup battery.

Honeywell wave2ex indoor alarm siren

Unlike most equipment on a Honeywell VISTA Security System, an added siren will always draw power from the panel's backup battery when activated, at least when the siren is connected directly with the panel. Normally, the backup battery is just sitting there dormant, ready to kick-in to power the system in the event of an electrical outage. It feeds a small amount of power from the panel's transformer to stay actively charged and ready. Once AC power is lost, the battery will take over and keep the system powered. However, the battery also has a big job in helping an added siren activate during alarm events.

When an alarm occurs on a VISTA-20P System, the siren will activate by drawing power from a source. If the siren is wired to Terminals 3 and 4 on the panel, then this source will be the system's backup battery. In this case, the battery will provide up to 2A of power at 10.5 to 13.8VDC to power any added sirens. This is important, as it allows the siren to still activate even if there is a power outage. But you must also consider that if the backup battery is removed or dies in this scenario, then the system's siren will not be able to activate. That is why it is always important to maintain a charged backup battery on the system. If you are looking for a new backup battery for your VISTA-20P System, then we recommend either the UltraTech 1240 or the UltraTech 1270, depending on the power needs for your system.

However, a user may decide to use an auxiliary power supply with their VISTA-20P System to power a siren. The purpose for this usually because the sirens they are adding will exceed the maximum allowed siren power output of 2A at 10.5 to 13VDC. If the user does this, then the siren will normally be drawing power from the power supply during alarm events. That being said, it is still extremely important that a backup battery is used with the auxiliary power supply in this setup. Otherwise, the power supply will have no way of remaining powered on in the event of an electrical outage. Most auxiliary power supplies have a charging circuit that will keep a battery charged during regular usage. While you can technically forgo a backup battery on this type of setup and still have a siren activate, doing so is strongly discouraged. For more information on adding a siren to a Honeywell VISTA Security System using a power supply, please review this helpful FAQ.

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Calculating power requirements for a Vista 20p system using Honeywell's power calculator spreadsheet. Planning for 2 sirens attached to the bell output: Honeywell 702 (sometimes listed as 1.5A and sometimes as 1.2A) and Wave2 (500mA). I also have approx 300mA draw on the auxiliary power terminals from the panel. The spreadsheet lists me as overdrawing the system in Alarm Mode (standby is obviously fine at 300mA of 600mA available). Should I expect any issues with this setup when connected to transformer power, or in the event of a power loss and everything is coming off the 9AH battery? I'm not too worried about the unlikely event of a 24 hour outage and a dead battery. More concerned with the sirens preventing the system from ever getting a signal out via Total Connect in the event of an alarm when the power goes out. Would prefer to avoid external power sources, and wondering if the 700mA 719 would be a better option, but I already own the 702. Thank you!

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