I’ve been trying to hunt down this issue for a while and finally made a few conclusions that may help others and also to ask a key question.
When my zigbee sensors drop battery level (not 0% but too low to communicate) they go “Unavailable” in HA as you’d expect. Checking their data they show something like:
Last Seen: 2023-09-17T18:49:06
Which is when their battery died. When this happens I go and replace the battery, however they never re-connect.
This particular device is a TH01 by eWeLink (Temperature and humidity sensor by Sonoff).
Leaving the battery out for 5 minutes and then back in doesn’t make a difference. It’s almost as though when they lose power they lose their pairing and you then have to delete and re-pair them all over again (but this isn’t simple as shown below).
I’ve eliminated signal strength as tested this with a sensor beside my Zigbee co-ordinator to confirm my theory.
Before the device lost power due to battery, it’s data showed up as:
IEEE: 00:12:4b:00:29:0f:85:07
Nwk: 0x4cd7
Device Type: EndDevice
LQI: 178
RSSI: Unknown
Last Seen: 2023-09-17T18:49:06
Power Source: Battery or Unknown
If I now delete the sensor, I put the device into pairing mode, go to add new in HA for Zigbee, it discovers but then it struggles to re-add. I suspect because some pairing/identification is still there so it adds the device but without any data (no temperature, etc). I have to delete and redo this quite a few times before it will work. But it comes back with different data:
IEEE: 00:12:4b:00:29:0f:85:07
NWK: 0xeb16
Device Type: EndDevice
LQI: 178
RSSI: Unknown
Last Seen: 2023-09-19T11:36:36
Power Source: Battery or Unknown
Perhaps somebody that knows Zigbee protocol/devices better could explain:
- Does the end device ‘store’ the co-ordinator/hub and so does it lose this when power is lost
- Does the ID somehow change when battery replaced
- Should ‘Reconfigure’ on the HA integration page work to re-establish? I’ve never had any success with this button!