Anyone know at what voltage a sonoff zigbee door sensor should need a new battery? It feels not that long since I replaced the battery in mine so I tested the voltage with a voltmeter before replacing it. It was reading 2.6v which I would have thought was ok for a while yet, but I couldn’t get it online again without a fresh battery.
I cannot help you with your question, but here is a thread you might find interesting. It is discussing the original SmartThings sensors with the CR2450 coin battery which is also a 3V battery like the CR2032 you mention. These sensors also required replacing the coin battery quite often as well. Ever since I replaced the coin battery with external AAA dual battery packs, I now only have to change them once a year or longer. But I have to put up with SmartThings advising the sensors have low battery (15% or below) since 15% battery life will now last me another 3-6 months or so.
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Update on this: looks like sonoff zigbee contact sensor has died again. Looks like the issue is not the battery, even with a fresh battery it’s not triggering. I re-paired it, also delete and reinstalled it but still no luck. I’d had been working for about 15 months using an 12v outlet electro magnet to trigger it. I wonder because had using the electromagnet long term that this eventually killed it, doubt it who knows?
Why?
When you switch the electromagnet on and off, it can produce inductive voltage spikes (especially if it’s a coil-type magnet). Those transients can couple into nearby low-voltage electronics, like your contact sensor, and damage its tiny input circuits or the Zigbee radio.
Poor thing…
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Because I wanted to trigger the contact sensor when the guardline driveway motion sensor triggered a chime at the non smart base. The idea as to make the non smart device smart by enabling it to trigger SmartThings events by using its trigger facility to turn on the electro magnet . It’s worked well enough for a bit over a year, but now it’s stopped and even though the contact sensor still pairs with SmartThings it’s stopped generating events. I can’t use a regular outdoor movement sensor because they generate too many false alerts from light changes, leaves blowing in the wind etc. the guardline gave very few false triggers.
Sounds like the actual reed sensor or hall-effect sensor is fried.
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Ok, new approach, I’ve abandoned the door sensor and electromagnet and replaced it with a water leak sensor with the two wires of the sensor stripped back and connected to the com and “no”, normally open contacts of the guardline base unit. When the driveway sensor triggers an event to the base station the contacts are closed for 10 seconds which is reported as the sensor going “wet”, I use a this even to then trigger SmartThings automations .
Only tried it for a few hours but it seems to be working ok for now.
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