alarm system on a UPS

[Del91574]

Just think about it - that hardware, the beeper, the display, the inverter, the transformers - they're all wasting energy. They're not going to run for 12 hours - BUT, getting something like another DC power supply with charger and battery (elk makes some) and supervisory outputs, you'll get much better efficiency making it run much longer - easily 12-24 hours depending on how you set it up. I don't see a conventional UPS lasting more than 4 hours.

Not knocking Elk's 212S' (I own and run 2 on my system and install them all the time), but in a case like this where runtime is of a concern, I'd choose a larger and more robust power supply that can run larger batteries. A 12AH battery on a 2A supply isn't going to last long. Something like an Altronix AL400ULXB would get you 4 amps, 0 voltage drop on switching to battery (huge issue with many supplies out there) and supervisiory contacts, in addition to supporting up to a 40AH battery.

 

[Steve]

Funny you mention that. My setup is as follows and if I did it again I would do the same thing... Alarm panel in 1 can, backed up by 2 8ah batteries in parallel. Altronix AL400ULXBin a can powering all PIR/GB, etc and backed up with 2 8ah batteries in parallel and relay contacts to a zone for supervision. Switch gear, Rain8Net, HDHDR etc in another can all backet up with a TrippLite structured wiring UPS. In your case I would use the UPS for all the switch/network gear and add the 2nd battery in parallel to the panel. I don't like the panel PS plugged into a UPS. As said before, you will get more efficiency and longer runtime off that plain battery in parallel and longer runtime on the switches without the panel load letting the UPS just do what it was designed for.

 

[Del91574]

The one item I can say with certainty, is when running an Elk with aux supplies, if any sort of data bus device is powed from them, make absolutely sure the supply provides 0V drop when running from battery only. Elk's don't like voltage sag on the data bus devices, otherwise very ugly things start to happen.