Toolworker
Well-Known Member
Just an update - My replacement 2021 Ultimate has the same 12v battery problem that the old 2020 did. It occasionally gets into a loop with the Aerovironment EVSE and drains the 12v battery. Happened to me again the other day. I mostly avoid it by keeping unplugged and only charging occasionally.
I would suspect the EVSE, but as reported above, I've seen problems with Hyundai's EVSE cord too - just not as drastic.
I haven't done any of the firmware updates since I got the car, which was manufactured in late 2020. I'll take it to the dealer and see if any of those fix the problem. They didn't on the 2020, although they did change the 12v charging pattern.

I would suspect the EVSE, but as reported above, I've seen problems with Hyundai's EVSE cord too - just not as drastic.
I haven't done any of the firmware updates since I got the car, which was manufactured in late 2020. I'll take it to the dealer and see if any of those fix the problem. They didn't on the 2020, although they did change the 12v charging pattern.