It does not happen on all devices. Lets just say battery reporting is very inconsistent. I believe most devices just go off voltage output to determine the battery level. Some devices feel like they could do a better job of determining the percentage, and others do it pretty good. Personally I just use the DAC app ([RELEASE] Device Activity Check - Get notifications for "inactive" devices) to monitor device activity and replace the batteries when the device stops working. I use the battery % to know when the device might stop soon but I let it fully die. None of my battery devices are mission critical.
That ER14250 looks very similar to the CR123A. I get pretty good results with those devices. The button batteries are the worst (CR2023, 2450 etc..), those will fluctuate under load so the percent goes up and down, and then I also have found some devices will get down to showing 1% but still work for months like that.
Here is some devices using the CR123A
This one only uses one battery, you can see it holds at 90% for most of its life then drops off and dies within a month at the end. This is how Lithium usually works.
These all use 2x CR123A (they are all Zooz ZSE40).
Here are my locks using AA Alkaline batteries, you can see they are more of a slow and steady decline. The front door just stopped working right last week and it was only at 80% so I never know when its going to stop working actually, again, very inconsistent. I really need to find some good inexpensive lithium AA to use in these, the voltage will hold longer so they will last longer.
