[flygdchman]

Thank you for the prompt reply and welcome to the forum.

Here is what the service invoice said.

"40131 Found history code for cell voltage variation. Inspecedted cell voltages. No variance present. Likely due to cold wether. Cleared. "

Back in March the 12 V battery failed and KIA replaced it. There was an issue getting it covered under warranty that required getting KIA customer service involved. I think the issue was on KIA's end and how they defined the warranty period for the 12V in the service info. Since then there have been no issues with the 12 V.

My suspicion is that the fault is being tripped during charging. We use the KIA supplied trickle charger other than the couple of times that it has been at the dealership.

Waiting for the dealer to give me a date to bring it back in.

 

[flygdchman]

I don't recall anyone on this forum with a similar problem. I am not familiar with the code; certainly not an OBD code.
Were you charging over 80% most of the time?
I am amazed that you got the 12V covered under warranty.

We do not charge the battery over 80% most of the time. We generally charge it to 90% once a week the morning before taking a weekly 180 mile round trip. In general have tried to keep the battery around 50% on a daily basis

2021 Niro EV 12 V Battery is warrantied for 36000 miles or 36 months whichever comes first. Our car was under both when the 12 V failed.

 

[flygdchman]

If this were me I'd monitor and log the 98 cell group voltages while charging the traction battery. Use an OBD bluetooth dongle and Car Scanner. I'd guess you'll find one group consistently unstable.

I appreciate this helpful suggestion.

I had suggested to the dealer that they do this. They probably don't want to because it would take more of their time than KIA will pay them to do it. So to your point I might have to do it myself.

I don't have any EV scanners tools.

 

[flygdchman]

These items are a trivial expense, the Car Scanner app works with either smartphone and is useful for any future EV. It might just take some patience watching while charging. But you can log the data as well and check it later.

What might be happening is that the BMS's voltage monitoring might be intermittently defective on one group and that's what's triggered a warning level. Somehow I recall this problem being reported before. It requires disassembly of the battery to repair.

I've marked the two items to watch with the yellow oval. If one cell group (of the 98) is faulty the number will be steady, identifying which one it is. You might also see the voltage variation show up momentarily in the graph at page 10. Generally a variation of 0.10 V across all the cells is a big problem. They should all be within 0.04, noting that the resolution is 0.02

View attachment 11024
View attachment 11025

Thank you for the follow-up reply. I really appreciate your ongoing support.

I edited my post and must not have properly saved it. My edit corrected my statement regarding not having any scanner tools. I was thinking EV specific. I do have a cheap OBDII bluetooth tranmitter that I did connect to the KIA last night and I also downloaded Car Scanner to my Iphone.

The result was, that I did get a DTC PF1AAF(00) which when I did a google search led to a TSB (attached) referenced in this post:

https://www.speakev.com/threads/fault-code-meaning.177977/#:~:text=P1AAF00%20-%20Abnormal%20voltage%20change%20detection%20logic%20issue

.
The post sounds similar to my experience.

I think that the TSB has been already performed on my car because if I read it correctly, it just decomposes a high level DTC into more specific ones which mine is showing.

The other result was the car scanner software had a message in the bottom of the page in red lettering stating:

"Defective ELM327 device detected! Your ELm327 device doesn't support commands required for connecting to specific modules.
Only basic OBD-II diagnostics is availible for this ELM327 device"

So I am assuming that means I need to get another (ELM327 v4.0) transmitter or dongle correct?

 

[flygdchman]

Took the car to the dealer yesterday. They said there was a bulletin to replace the BMS if clearing the codes didn't work so they ordered a new BMS for it. Suspect that this is a battery issue that a new BMS is not going to fix. My thinking is based on this thread and Recurrent is showing a sudden drop in the battery capacity. We'll see.....

 

[flygdchman]

Dealer replaced the BMS today. It did charge past the 80% limit this morning. We'll see if that holds....

 

[flygdchman]

Well as I suspected the EV light came back on when the car got up to 84% on it's way to 100 (it won't charge any further and after it drops below 80% I'm sure it won't charge above 80%. I texted my SA this morning. Of course he hasn't responded yet.

 

[flygdchman]

Took it in yesterday. When I got there my SA had me talk to their lead EV tech who has taken my car on as a project. In addition to the EV system fault which limited the charging to 80% max the inverter coolant fault also tripped. We had the flush done per the recall last year. They reset the EV system fault which is the same one as before, charged it to 90% drove it then charged it to 100% and flushed it again. They told us to drive it until we get down to 70% and they will charge it again to see if the fault trips again. So I feel like they are trying to figure it out. So I am good with the dealer.

The car has 41K miles on it. It's a 2021 and will be in service for 4 years this fall.

 

[flygdchman]

Took it to the dealer today per their request to bring it in once it was below 70% so that they could charge it and see if it would throw any codes. They were able to charge it again without triggering a code. On the way home the refill coolant light came back on. Will be charging it ourselves this weekend. Will see if that triggers a code.

 

[flygdchman]

Well it may be fixed. As mentioned above the dealer charged it to 100% a couple of weeks back and I have charged it to 85% and 94% in the last week so hopefully that issue is behind me. Now I have to get through an intermitent refill coolant light problem.