CharlesBranch
Member
The car has been parked for about 9 days now, and so far, the 12-volt battery has not died. The first image shows the BM2 recording for the day of the trip. Just before the trip, I charged the traction battery enough to leave about 10% remaining after the trip. On the return trip, we ran into a major thunderstorm, and we had to detour off of I-65 and wait about 30 minutes. That meant that we just barely made it home with only three miles to spare.
The second image shows the BM2 record over the next 9 days. The voltage gradually dropped from 12.62 to 12.5, but the 12-volt battery never died. 
There were three small negative spikes over the 9 days. The first was when I queried the status of the car. The second was when I opened the hatch the next day to unload some items, and the third I believe was when my wife opened the doors looking for a lost earring. The traction battery never tried to charge the 12-volt battery during the nine days, but the 12-volt battery voltage decreased so slowly that it never entered the vicious cycle I observed before. My assumption is that when they changed the ICCU to fix the separate slow charging problem, that also fixed the dead battery problem as well. It's not impressive that two different dealers on three different occasions never took my dead battery problem seriously, and if I had not subsequently had a separate problem, my guess is that they never would have fixed it. I had previously criticized the apparent decision of the design engineers not to use the traction battery to recharge the 12-volt battery when the traction battery was below a certain value (probably about 20%). Now that it looks like the dead 12-volt batteries were the result of excessive drain, I am a little less critical of that design decision. Although I am now less critical of the design engineers, I am still very critical of the three service teams who refused to pay attention to the recordings I gave them and refused to even contact Hyundai to see if someone with more expertise might have a suggestion. Had they done so, I suspect that a competent engineer would have quickly seen that there really was a problem. And I am still critical of the Hyundai customer service people, who also refused to address the problem and just referred me back to the dealer, who had already demonstrated that they were not competent to diagnose the problem.
I'm looking forward to resuming use of the car, which I really love to drive. For the last 9 days, I have been driving my old Honda Element, which has been a great car with not a single mechanical problem. But my wife will still refuse to drive the Hyundai. She still calls it a lemon, and I can't really fault her for that.
