If the device takes a 3v battery then it shouldn’t/can’t require more than 3v to function because not all 3v batteries are capable of producing more than 3v. Is there a message near the battery that says it requires a specific brand?
I think most Zigbee devices report the battery in volts and the DTH performs the calculation to determine the battery level. If that’s the case with the DTH your IRIS motion sensors are using you should be able to easily adjust that calculation.
Have you looked at my Simple Device Viewer SmartApp? It can send you notifications if the battery drops below the threshold you set and it can also send notifications if it hasn’t checked in with ST for a specified amount of time or SmartThings marks it as offline.
It has also allows you to see the battery level of all your devices from a single screen.
That SmartApp won’t help if the device is still reporting 100% when it dies, but it worked great for the ST Motion sensors that used to die while showing 60%.
I purchased some ST Motion Sensors when I got the hub, but all of my other motion sensors are z-wave and I no longer purchase zigbee devices.
They occasionally report false motion events and 2 of them stopped reporting motion after about a year so now they’re just temperature sensors.
Yes, 10 seconds is the lowest, but you can set it a lot higher.