When you say "the warnings flashed again" after replacing the battery, are you sure that it was the same warnings that occurred with the previous battery or possibly different warnings? The reason that I asking is because of a very possible scenario:Hello, trying to get some feedback on some trouble with our 2018 Clarity Touring. My wife was driving it yesterday and the car started showing a red battery warning light and the messages shown above in the subject. It also warned to stop driving as soon as possible. My wife pulled into a nearby parking lot and the car soon died. She was able to restart it a few minutes later and drive home, but the car died again in our driveway. The HV battery was still over 1/2 full. Seeing as it was -1 F outside, I figured the battery was crapping out as it was over 3 years old. I charged it a bit, parked the car in the garage, and let it sit on a battery tender for the night. The next day, I figured I'd give it a try. The car started normally but didn't even make it out of the driveway before the warnings flashed again. I then decided to replace the battery with a new one, but, again, it started normally but I didn't make it past the driveway before the warnings started again. I have performed an OBD scan using and OBDLink MX+ and Torque Pro and OBDLink apps and neither app showed a trouble code. Does anyone have ideas as to what is going on here? Are there fuses to check? Where? Thanks in advance for any input.
- Your 12V battery as you suspect was done. Normally however this would only affect starting the car, but in some cases a really far gone 12V battery will cause warning messages to appear while driving. Somewhat unheard of however is for a bad 12V battery to cause the car to die once it is running, but it might be possible.
- After replacing any 12V battery in the Clarity, or even disconnecting a healthy battery for a few seconds, it is perfectly normal for the instrument panel to display several ominous warning messages about failures of VSA, ABS, TPMS and I think one other. Yes that is perfectly normal to see those type of warning messages anytime the 12V battery is disconnected. These messages clear in less than a mile of driving.
If it's not those messages, or whatever messages you are getting don't go away within one mile, then there would likely be something else wrong with the car. But without further details about what error messages you have been seeing I am leaning towards it being the scenario that I described. I.e. just a 12V battery that went bad, as you surmised likely due to the sub-freezing temperatures, and then the normal "boo" that the Clarity does whenever the battery is replaced or the 12V is disconnected.