No I'm afraid most devices seem to be quite inaccurate or vague with their battery reports. I use a community app called Device Activity Check [RELEASE] Device Activity Check - Get notifications for "inactive" devices
that tells you if a device hasn't called in at all within a time period you specify. If you have a chatty device that usually updates the temperature or whatever every hour, you can set the app to let you know if it's not been heard from in over an hour. So at least you can change the battery very soon after it's died.
If it's very important to not have a battery run out, to be on the safe side change it if it gets near 50%
