PSA for Aeotec ZW074 4-in-1 sensors

Just a quick PSA for anyone who has one of the old round “Gen5” ZW-074 multi sensors (motion, temp, light, humidity). I have a few of them, and made the mistake of moving one from powered to battery. On doing so, I’ve now found that the motion sensor no longer works, although it was working fine when powered via USB. Moving back to USB doesn’t bring motion sensing back, even after a full reset (holding down the button for about 20 seconds until the light goes solid then turns off). I suspect that a capacitor somewhere has failed that in turn is stopping the thing from properly being reconfigured.

Basically, if your ZW074 sensor is working - leave it alone unless you are willing to accept the risk you may lose the motion sensor. Just to be sure, I tried on a second sensor and it also now no longer detects motion. Temp, humidity, and light all work fine though.

FWIW #1 As an aside I had made this change a number of times in the past without an issue, so I am pretty certain it’s a hardware glitch. They are over 5 years old now, so these things happen. I might still use them to monitor temp/humidity, though.

FWIW #2 If you want to live on the edge and play with yours, it may be a while since you last did it so as a reminder when you move from USB to battery you do need to remove the sensor from the network, then ideally reset it to defaults (hold the button down for 20 seconds until the light goes solid then off), put the batteries in and then add it back in to the network. This is to make sure it knows it’s on battery, otherwise it will drain the batteries really quickly. It is also a good idea to have the sensor near the zwave gateway when pairing, and after pressing the button on the sensor to add the sensor in you should tap the button another three times quickly to keep it on for a few minutes (the red light will stay on) to give it time to exchange keys (comms are slower the further away it is and/or you don’t keep it on it is likely to fail part way during the process as the sensor will go into battery saving mode).

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Specifically, the gateway should be brought to the device’s location, not the device to the gateway. It’s very important that the device be included from the physical location it will have in the mesh. Otherwise, neighbors will not work properly (and maybe… motion reporting?).