Can I power an Aeon Labs Multisensor from an existing alarm power supply?

I would like to buy an Aeon multisensor and wire it into a power supply so I don’t have to change batteries.

It takes a 5V USB supply apparently.

Already I have an existing hardwired PIR alarm sensor in the room nearby. Does anyone know what power supply alarm sensors usually use? It is a Honeywell alarm that has been there a long time.

I was thinking if it is the same I could tap into the alarm sensor’s power supply to avoid laying new cable? Please tell me if that is a bad idea!

Bad idea! Pretty sure most alarm components are 12v and the board/wiring are definitely not designed to handle the type load you are talking about.

The Honeywell/Ademco panels are supplied with a 16.5VAC 40VA power transformer (as are most other panels such as the DSC units and the GE/2GIG units). This is converted by the panel to 12VDC 600ma available on the aux power terminals. This maximum is shared by all devices powered directly by the panel, such as keypads, active sensor (such as wired motion sensors), communicators, zone expanders, relay modules, wireless receivers, etc… Now, even with newer Honeywell keypads, a single keypad (250ma - 300ma) and two or three older motion sensors (40ma -80ma) you are using up most for your panels power budget.

So, the correct answer, as stated by jsams, is that powering any more sensors from the panels power supply is a bad idea.

The solution, for adding more devices (keypads, sensors, etc) is to power the main keypad and primary sensors from the panel’s aux power terminals, and power additional devices from an auxiliary 12VDC 1.5An (or greater) power supply (sharing the ground of the Auxiliary Power with the panel ground at the Aux terminals on the panel). The problem of 12VDC to 5VDC can be solved with a small buck converter (most are small enough to be mounted to the back of a corner mounted motion sensor).

If the existing PIR in in a nearby room, it will be a lot easier running wires for the multisensor to an AC outlet in the same room than it will be extending the existing cable to the multisensory.

Ok. Sounds like powering from the alarm was a bad idea.

I could mount it near to the ceiling light in the hallway. That way I could tap into the ceiling light’s power supply and link that to a cheapo USB power transformer. That would be OK wouldn’t it?

The biggest problem will be getting to the ceiling, as I’d need to lift a couple of floorboards in the room above and that room is carpeted and full of furniture.

I also just looked at the Multisensor mainly because they advertise it can be run from the AC outlet (with a transformer) instead of batteries. Is there an easy USB connection or something similar or do they require the same hack as here:

They use a normal mini USB connection. My recommendation though is to first use them on battery and put them where you think you want them and run it that way for a bit. I found where I wanted them and where they ended up to be different.

waynehead99, thanks for the reply. This sounds all good. Looking at the reviews of the Aeon Multisensor there seems to be some major hassle to get it working with the Vera, though. Have you looked into other options that can measure temperature and do not require batteries?

I have 3 of them and they were a pain in the beginning but there is lots of info on the forum about how to get them right. They do use batteries quick but since your using USB that’s not an issue. I went a different way and use Arduino now for the rest of my sensors. I can build them cheap and they are reliable.