About a month ago, I went out to find my e-Niro 12V battery dead. Called KIA roadside assistance to help get it started and I drove it to the dealer. They, of course, could find nothing amiss and had no suggestions.
I immediately ordered a Li-ion starting battery, as well as a trickle charger, just in case.
Anyway, one night I noticed that the right-hand green charging light (right-hand when viewing through the windshield) was blinking. I never had seen that.
I checked the manual and it states that it blinks when charging the 12V battery. The lamp was out the next time I looked.
The car was just sitting, not charging at the time.
Interesting. Hope this helps. Although, it would be nice to know the conditions that this happens in.
There is a setting that will charge the 12 volt battery when the car is not on or plugged in. When the green light is flashing that is what is happening, you can set it to not charge the 12 volt battery in that manner.