[yticolev]

I’ve tried two different OBD readers with similar ultra low current ratings. Both triggered an excess current warning overnight opening a relay on my HEV disconnecting the 12 volt battery to prevent battery damage. So I don’t trust anything plugged into the always live obd port. Try unplugging the dash cam and see if problem goes away.

Your 12 volt battery has already suffered some damage. A smart trickle charger may reverse some damage. If your battery maintainer is not “smart”, it won’t help.

 

[yticolev]

No, not a smart charger.

 

[yticolev]

Having a 12v that's now in its fourth year, I'm hoping to prolong its life some more.

Great life! Instead of endless 12 volt issues threads and who has the highest mileage threads, perhaps we need a who has the longest lived 12 volt battery thread and concurrent smart charger use, if any.

 

[yticolev]

Kia also hints that since the 12 volt battery is charged by the high voltage drive battery, if the high voltage battery is low on charge, that may prevent the 12 volt battery from being charged to protect the high voltage battery.

I think that could be accurate. Lead acid 12 volt batteries cost far less than traction batteries and so could be sacrificial. Although to what purpose? There is something else going on if the traction battery dips below the bottom buffer in a PHEV. The BMS normally doesn't allow that.

 

[yticolev]

we will see if it is the factory 12v battery or the system charging it.

Spoiler, it is both.