22 Kona keeps going into Turtle mode after sched. Maintenance

Well considering the reduction gearbox oil change is done under the front of the car and on a hoist it should take 30minutes max, that story sounds like the biggest load of BS ever.
What they were up to with the HV battery is anyone's guess, but obviously they stuffed up whatever they were doing, I have a 2022 Kona EV I certainly hope they leave the thing alone, they sound like a bunch of muppets.
What area are you from?

 

In my Kona they changed the oil in the reducer and it took them no more than half an hour. After all, in the service materials of the manufacturer there is a procedure for changing the oil. You can also find it on youtube, I believe. Why bother with disconnecting the traction battery? This is indeed another case of BS in American Hyundai services.

 

First thing I would be doing is ringing Hyundai Canada's head office and explaining what happened.
Then asking them if there is somewhere else nearby, that is more technically proficient with the Kona EV, as you have lost confidence in the competence of the dealership.
If that fails give your consumer protection authority a call, if Canada has them, in Australia each State has a Government consumer protection department.

 

First noting that the dealer has every right to apply whatever safety procedures are specified by their training, or that they think are necessary without judgement from us. Certainly no DIYer has ever disabled the traction battery before a gear oil change but that is our risk to quantify and accept.

It seems clear that they pulled the main fused disconnect behind a small cover in the floor pan under the rear seat. If it were me I would go in there and remove and reseat that part, checking that the blade contacts are not burned or damaged. I can't see what else it could be? Obviously this is at your own risk but it is designed to be safe to remove, just like an old fuse block on a residential electrical panel. But it's even safer because the pack is already isolated and disconnected internally when the car is "off". Otherwise ask them to do it, but you'll probably be billed for it unless it's visibly damaged.

I am concerned that the dealer changed their story but on the other hand being a warranty repair they aren't really obligated to provide details other than when it's ready to pick up.

 

Pulling the main disconnect doesn't affect the driving stats because those are supported by the 12V battery. However, disconnecting the 12V battery would be done prior to removing the main disconnect. So, in the end we still don't know if they pulled the disconnect other than accepting their word. It should not be too hard to check that the disconnect is fully seated without removing it, not that I've done it myself. It has a lever on the top that when swung over to the locked position ensures that the part is fully seated. I'm just thinking that they may have partly opened it.

I do recall a short term turtle warning being reported once or twice in the past but don't know what the resolution was. A search might reveal that. It's certainly not a common occurrence and often people report things, it gets fixed and they never think to report back on the forums.

First, I would disconnect the 12V battery for 10 minutes to ensure standby systems booted cleanly. That can be done at the (-) battery connection. Replace it firmly and deliberately to minimise power glitches. If you have a voltmeter check the 12V battery voltage while its disconnected. It should be at least 12.5.

Has anyone checked traction battery cell balance? They should not differ by more than 0.02V at higher SoCs, at least 80%.

As for the SoH I don't think that's unusual. My original battery was still 100% after 4 years and 23,000 km, but I was careful with it. There have been a handful of recent reports around 94% but there's generally been an identifiable reason like living in a hot geographic location or frequent DC charging. I don't think the 100% is related to this problem.

 

Ok, so the battery pack is likely fine.

 

I'm 100% and good balance at 30,000 kms. My dealership didn't isolate the battery while changing the gear oil for me.

 

If any of the battery cells were damaged (too low voltage), the SoC would probably not show 100%, but 0%. And the range is not, for example, 460km, but about 40km. Going into turtle mode must be for another reason. It is worth searching the web to find a list of parameters that cause the car to go into turtle mode, apart from the traction battery discharge (e.g. battery temperature?). I wonder if any diagnostic codes appear.