Aeotec Multisensor 6 - Battery Reporting Interval (Lux)

Long time lurker here, hoping to get some help configuring my Multisensor 6 for my use case.

We have a fridge with double doors (and there doesn’t seem to be room for a door sensor), and I’d like to use the multisensor to detect when the lux is above a certain threshold (the door is open). I’ve got the sensor reporting values correctly, but I’m wondering if I can set it up the following way:

When motion is detected (door is opened), lower the reporting interval (and/or polling interval) so that values are reported more often (say once every 30 seconds or so), until motion is not detected for some amount of time (go back to sleep). That way I can measure the lux in the fridge, and send notifications to our phones saying the door has been open for longer than a few minutes (this has been a recurring problem for us).

Is something like this possible with the multisensor? Or is there a better device that I should be using?

You can do this with that sensor but it will chew through batteries. It’s because of the zwave. Unfortunately I don’t have another solution. I was talking with friends the other day about this. One of the guys has a device (cost about $60) that makes a really loud audible beep if the temperature drops in the refrigerator. Essentially saying power is out or door is open. I don’t know the name of the device, also it doesn’t connect to any network. IIRC, the battery life was ~2 years. Again, this is all word of mouth.

I wonder if it’s possible to compensate for the battery loss by lowering the reporting interval when the device goes back to sleep. Since it’s in the fridge, I only really care about the lux for the first couple minutes after movement is detected, after that it could report much less often (right now it’s at the 1 hour default).

Worst case, I can simply lower the reporting interval to something reasonable (say 30 minutes), and do a similar automation, I’d think it’d work for the extreme circumstance (open for 30 minutes or more), but I’d lose out on the “open for more than a minute” notification that I’m aiming for.

It’s been a while since i set up my mutlisensor, but if I recall correctly, HA wasn’t set up to dynamically change the polling rate. I think I have it working in 6 minute intervals. It reacts immediately to motion but only reports every 6 minutes. Something like that.

Maybe I could just lower the polling rate even though the sensor goes back to sleep? Will that make the network too noisy? Do you know if the sensor will go back to sleep immediately even if it’s being polled?

You can, i don’t think it will affect the network much. It will just drain your battery. Edit: battery life for my polling rate of 6 minutes with 1 hour updates is about a year. So if you update the polling rate to be less, you can expect to change that battery frequently.

Worth having a second look at that! :slight_smile:

Ask yourself this:

  • What is the annual cost of replacing the Multisensor’s (pricey) CR123 batteries?
  • How frequently are the fridge doors left open?
  • What is the average incremental cost of consumed electricity when a fridge door is left open?

Basically, if battery costs exceed electricity costs, this plan makes no cents. :wink:

I didn’t even factor in the purchase price of the (pricey) Multisensor …

I think another hidden cost is thrown out food from leaving the door open.

Are there any recommendations for door sensors that might fit on a standard double door fridge?

To cause spoilage? Door open … and fridge off … and no one noticing that arrangement for 2+ days. :slight_smile:

Are you wedded to a particular technology? You chose an Aeotec Multisensor so I assume you’d prefer zwave?

Plenty of small form-factor contact sensors available but the question remains, where will you install them so they are discreet?

FWIW, my double-door fridge has doors whose top-edges rise about 1" above the top-edge of the actual refrigerator. That would a reasonable spot to install contact sensors. The half with the sensor and battery and electronics rests on top of the fridge and the magnetic half attaches to the door, just above the door gasket and on the 1" lip. Close the doors, sensors are hidden. YMMV.

ZWave is my tech of preference for now - that’s a great point about the space above the fridge, mine has the same.

I’ll still need to make a decision on the best sensor to buy, but I’m thinking that’s a good option for me. That way I won’t have to worry much about the automation either.

Disclaimer: I don’t have a single wireless contact sensor in my home, everything is hard-wired.

Now that you know I am far from being an expert in zwave gadgetry, I found this, reasonably-priced, device made by NEO (Amazon link).

Based on the photos, my first concern would be that the magnetic half would need to be rotated 90 degrees in order to attached to the lip of the door top-end. None of the photos show it in that orientation. Theoretically it shouldn’t matter because it’s just a magnet … but just something that needs to be confirmed. Worst case, Amazon has a very good returns policy.


BTW, I have been considering a few applications requiring wireless sensors and I’m leaning towards 433MHz sensors. They’re inexpensive (< $10) and typically have great range and last long on (typically) AAA batteries. There are several options for the receiving end. I’m considering using rtl_433 with an SDR (software defined radio; <$30 for a good one from Nooelec and less than that for knockoffs). The output from rtl_433 can be easily converted to publish to MQTT.

Someone mentioned this 433Mhz contact sensor in another thread. Key advantage over other sensors of its type is the ability to report open and closed states. However, it can’t compete with zwave and zigbee contact-sensors in terms of small-size and styling.

Just bought a two pack of those NEO sensors. I’ll give em a try and report back in a few days! Thanks for the recommendation about the space above the fridge, I’ll let you know how it works out!

EDIT: Received the sensors and set them up without issue. Just changed the binary_sensor that’s auto-detected to a door device-class. Other than that, I was able to mount the sensor above the fridge as described, though I had to put the tape on the side of the small sensor rather than the bottom. Working great with a pushover integration!