Monitor Ioniq 5 12-volt Battery with BM2 battery monitor

[CharlesBranch]

On July 16 I posted a new thread on problems I had when the 12 volt battery died.
https://tinyurl.com/4ekfrhsj
Electriceddy suggested that I install a BM2 battery monitor and report back.
My BM2 has been monitoring the battery for a couple of weeks now. The image below shows the voltage over a 15 day period. The voltage goes up to about 14.7 volts and then gradually decays down to about 12.7 volts. The three periods indicated by the horizontal white lines represent three days when I made the same 3 short trips during the day.


It looks like each time I take a trip, the battery charges at a voltage of about 14.7 volts. I think some, but not all, of the other spikes also represent trips. I'm not sure what the small negative spikes are. I have not taken any long trips, so I don't know whether the voltage would have stayed at about 14 volts or would have dropped back down.

So far I have not seen a repetition of the battery going dead like it did in my original post.

I'm still happy with the car in spite of the strange battery problem and the burning odor I still experience when I start it in the morning after it has sat for a few days.

 

[electriceddy]

On July 16 I posted a new thread on problems I had when the 12 volt battery died.
https://tinyurl.com/4ekfrhsj
Electriceddy suggested that I install a BM2 battery monitor and report back.
My BM2 has been monitoring the battery for a couple of weeks now. The image below shows the voltage over a 15 day period. The voltage goes up to about 14.7 volts and then gradually decays down to about 12.7 volts. The three periods indicated by the horizontal white lines represent three days when I made the same 3 short trips during the day.
View attachment 17745

It looks like each time I take a trip, the battery charges at a voltage of about 14.7 volts. I think some, but not all, of the other spikes also represent trips. I'm not sure what the small negative spikes are. I have not taken any long trips, so I don't know whether the voltage would have stayed at about 14 volts or would have dropped back down.

So far I have not seen a repetition of the battery going dead like it did in my original post.

I'm still happy with the car in spite of the strange battery problem and the burning odor I still experience when I start it in the morning after it has sat for a few days.

On July 16 I posted a new thread on problems I had when the 12 volt battery died.
https://tinyurl.com/4ekfrhsj
Electriceddy suggested that I install a BM2 battery monitor and report back.
My BM2 has been monitoring the battery for a couple of weeks now. The image below shows the voltage over a 15 day period. The voltage goes up to about 14.7 volts and then gradually decays down to about 12.7 volts. The three periods indicated by the horizontal white lines represent three days when I made the same 3 short trips during the day.
View attachment 17745

It looks like each time I take a trip, the battery charges at a voltage of about 14.7 volts. I think some, but not all, of the other spikes also represent trips. I'm not sure what the small negative spikes are. I have not taken any long trips, so I don't know whether the voltage would have stayed at about 14 volts or would have dropped back down.

So far I have not seen a repetition of the battery going dead like it did in my original post.

I'm still happy with the car in spite of the strange battery problem and the burning odor I still experience when I start it in the morning after it has sat for a few days.

The 12V sag is the BMS reading the cell open circuit voltages. Thanks for the above info, it might provide more details if the time range is set for 24 hour intervals. It would be easier to distinguish drive spikes from those automatic programed charge spikes( on Kona EV it recharges for about 20 minutes after a short drive, reoccur about 2 hours later- using newer LVDC software version: then settles into a 4 hour cycle similar to the original version) , they also may occur when recharging the HV battery as well. It has been found that if the HV pack is less than 40% SOC, no charging of the 12V battery occurs as well. I can't vision too much difference in the charging pattern between Ionic 5 and Kona EV, except if the software version is changed. Both models should be using the method described in this Hyundai patent
I might add there have been numerous 12V battery failures associated with Bluelink services where the car will not go to sleep and thus interferes with the auto recharge cycle. I have not enabled this on my newer model for this very reason.
Also suggest PM @Domenick and see if you can add 12V between Ionic5 and battery in the thread title to avoid confusion with the HV pack (if it is too late to change it yourself)

 

[CharlesBranch]

It would be easier to distinguish drive spikes from those automatic programmed charge spikes( on Kona EV it recharges for about 20 minutes after a short drive, reoccur about 2 hours later- using newer LVDC software version: then settles into a 4-hour cycle similar to the original version) , they also may occur when recharging the HV battery as well.
...Also suggest PM @Domenick and see if you can add 12V between Ionic5 and battery in the thread title to avoid confusion with the HV pack (if it is too late to change it yourself)

Attached is the 24-hour chart for today. The three 14-volt spikes correspond to the same three trips as on previous days. The first and last were about 30 miles, and the middle one was about 5 miles.

So far as I can tell there were no additional charging cycles other than the three trips. I'll keep watching for the next day or two, when I have no trips scheduled.
BTW: I could not figure out either how to edit the title to add the 12-volt reference, and also could not figure out how to PM Domenick to ask him to edit it.

The Ioniq 5 12 volt battery charging sure seems a lot more complicated than the generator system in my old 1957 Plymouth. On that car, the generator once failed in the middle of the night during a long trip, and I was able to slide a long screwdriver behind the brushes, fashion a spring out of the elastic from my underwear, and finish the trip without incident. Fat chance of jury-rigging a solution like that on this car.

 

[CharlesBranch]

...Thanks for the above info, it might provide more details if the time range is set for 24 hour intervals.

I have now run the BM2 for longer periods.
The first image shows a seven-day period in which I made the same three short trips on day 1 and then left it parked for the next six days. The charger came on for the three short trips and came on several times during the next six days with no trips. The 12-volt charger appears to activate when the battery decays below about 12.7 volts, but does not come on during brief negative spikes even below that value. I think the fairly big negative spike indicated by the arrow on August 10 was when I noticed that I had disabled Bluetooth on my phone and had to reconnect. I noticed that spike as soon as I reconnected. I don't know what caused the other negative spikes over the seven days. Also attached is a one-day image of August 10 showing that spike in closer detail. That spike did not trigger the charger to come on, but it did come on at 18:50 hours and stayed on for about thirty minutes. Presumably, the gradual decay in voltage is caused by some constant power drain even when the car is shut off. I don't think that explains the problem I had with a dead 12-volt battery in my previous post, because it had been sitting only a day or two that time. The voltage certainly decays at a much faster rate than I am used to with my older cars. I sometimes leave my Honda Element sitting for a month or two, and the battery is able to crank the engine with no difficulty. I suppose that the Bluetooth itself could be responsible for some of the decay. I may turn it off if I can and monitor the voltage again.
Anyway, the algorithm of the charging system appears to be to turn on the charging when the voltage decays below a certain rate, but not if it just spikes below that voltage. As to the causes of the negative spikes, that's a mystery to me.

 

[electriceddy]

I have now run the BM2 for longer periods.
The first image shows a seven-day period in which I made the same three short trips on day 1 and then left it parked for the next six days. View attachment 17869 The charger came on for the three short trips and came on several times during the next six days with no trips. The 12-volt charger appears to activate when the battery decays below about 12.7 volts, but does not come on during brief negative spikes even below that value. I think the fairly big negative spike indicated by the arrow on August 10 was when I noticed that I had disabled Bluetooth on my phone and had to reconnect. I noticed that spike as soon as I reconnected. I don't know what caused the other negative spikes over the seven days. Also attached is a one-day image of August 10 showing that spike in closer detail. View attachment 17870 That spike did not trigger the charger to come on, but it did come on at 18:50 hours and stayed on for about thirty minutes. Presumably, the gradual decay in voltage is caused by some constant power drain even when the car is shut off. I don't think that explains the problem I had with a dead 12-volt battery in my previous post, because it had been sitting only a day or two that time. The voltage certainly decays at a much faster rate than I am used to with my older cars. I sometimes leave my Honda Element sitting for a month or two, and the battery is able to crank the engine with no difficulty. I suppose that the Bluetooth itself could be responsible for some of the decay. I may turn it off if I can and monitor the voltage again.
Anyway, the algorithm of the charging system appears to be to turn on the charging when the voltage decays below a certain rate, but not if it just spikes below that voltage. As to the causes of the negative spikes, that's a mystery to me.

Thanks for posting. I believe (as posted above) lower spikes occur when it activates the BMS to check the cells for any deviations at regular intervals. At least those are on a regular basis. What I don't see, is any regularity in the 12V top up as we have in our Kona EVs. I suspect an update eventually will be applied to Ionic 5 to address that issue.
I suspect you are correct in the larger downward spike being Bluetooth, which is similar to when Bluelink activates (which is why I opted out to enable) as this has been a factor to several dead 12V batteries posted in the Kona forum.
I am curious as to what will happen when the OTA updates are enabled in N.A. (maybe just in Europe for now to see what happens- Hyundai to monitor). The last thing one would want is an OTA update at the end of a non 12V charging period. Remains to be seen I guess

 

[CharlesBranch]

Since my last post, I have had two more incidents, which I call "near misses."


In the first incident, I happened to take the car to the a charger and noticed the beginnings of a voltage spiral on the BM2 monitor after I returned. On the second incident, I got a warning message from the BM2, and I connected a 12 volt charger to bring the battery back up. On this second near miss, I noticed that the main battery was at 20%, so that appears to eliminate the possibility that this occurs only when the main battery is below 15%, as it was in the other incidents. I have an appointment with a different dealer tomorrow and plan to leave it for several days to give them a chance to see it happen.

BTW. I found a YouTube video posted by Andrew Till, who also experienced what looks like the same problem. https://tinyurl.com/45r86r96.
He said that his dealer installed a BMS update, which he thought might have solved his problem.

 

[Zuinige Rijder]

I also made a tool to monitor the 12V battery values, your drives, charging/discharging, consumption figures using Bluelink functionality. You can find it here:
Automatic trip administration tools for Hyundai Bluelink users. You can see the fluctuation in the 12V battery in % (warning level is 65%) and also when you have driven.

Example of what is captured, including 12V%:

datetime, longitude, latitude, engineOn, 12V%, odometer, SOC%, charging, plugged
2022-09-17 15:00:55+02:00, 5.124957, 51.68260, False, 90, 17324.2, 54, False, 0
2022-09-17 16:00:51+02:00, 5.124957, 51.68260, False, 90, 17324.2, 54, False, 0
2022-09-17 17:00:52+02:00, 5.124957, 51.68260, False, 90, 17324.2, 54, False, 0
2022-09-17 18:00:53+02:00, 5.124957, 51.68260, False, 90, 17324.2, 54, False, 0
2022-09-17 19:00:51+02:00, 5.124957, 51.68260, False, 90, 17324.2, 54, False, 0
2022-09-17 20:00:42+02:00, 5.124957, 51.68260, False, 90, 17324.2, 54, False, 0
2022-09-17 21:00:45+02:00, 5.124957, 51.68260, False, 90, 17324.2, 54, False, 0
2022-09-17 22:00:37+02:00, 5.124957, 51.68260, False, 90, 17324.2, 54, False, 0
2022-09-17 23:00:29+02:00, 5.124957, 51.68260, False, 91, 17324.2, 55, True, 2
2022-09-18 00:00:36+02:00, 5.124957, 51.68260, False, 91, 17324.2, 58, True, 2
2022-09-18 01:00:42+02:00, 5.124957, 51.68260, False, 91, 17324.2, 60, False, 2
2022-09-18 02:00:47+02:00, 5.124957, 51.68260, False, 91, 17324.2, 60, False, 2
2022-09-18 03:00:42+02:00, 5.124957, 51.68260, False, 91, 17324.2, 60, False, 2
2022-09-18 04:00:41+02:00, 5.124957, 51.68260, False, 91, 17324.2, 60, False, 2
2022-09-18 05:00:42+02:00, 5.124957, 51.68260, False, 91, 17324.2, 60, False, 2
2022-09-18 06:00:51+02:00, 5.124957, 51.68260, False, 91, 17324.2, 60, False, 2
2022-09-18 07:00:43+02:00, 5.124957, 51.68260, False, 91, 17324.2, 60, False, 2
2022-09-18 08:00:47+02:00, 5.124957, 51.68260, False, 91, 17324.2, 60, False, 2
2022-09-18 17:00:44+02:00, 5.124957, 51.68260, False, 91, 17324.2, 59, False, 0
2022-09-18 18:00:47+02:00, 5.124957, 51.68260, False, 91, 17324.2, 59, False, 0
2022-09-18 19:00:48+02:00, 5.124957, 51.68260, False, 91, 17324.2, 59, False, 0
2022-09-18 20:00:45+02:00, 5.124957, 51.68260, False, 91, 17324.2, 59, False, 0
2022-09-18 21:00:42+02:00, 5.124957, 51.68260, False, 91, 17324.2, 59, False, 0
2022-09-18 22:00:48+02:00, 5.124957, 51.68260, False, 91, 17324.2, 59, False, 0
2022-09-18 23:00:44+02:00, 5.124957, 51.68260, False, 91, 17324.2, 59, False, 0
2022-09-19 00:00:46+02:00, 5.124957, 51.68260, False, 91, 17324.2, 59, False, 0
2022-09-19 01:00:41+02:00, 5.124957, 51.68260, False, 91, 17324.2, 59, False, 0
2022-09-19 02:00:43+02:00, 5.124957, 51.68260, False, 91, 17324.2, 59, False, 0
2022-09-19 03:00:42+02:00, 5.124957, 51.68260, False, 91, 17324.2, 59, False, 0
2022-09-19 04:00:41+02:00, 5.124957, 51.68260, False, 91, 17324.2, 59, False, 0
2022-09-19 05:00:42+02:00, 5.124957, 51.68260, False, 91, 17324.2, 59, False, 0
2022-09-19 06:00:44+02:00, 5.124957, 51.68260, False, 91, 17324.2, 59, False, 0
2022-09-19 07:00:49+02:00, 5.124957, 51.68260, False, 91, 17324.2, 59, False, 0
2022-09-19 08:00:56+02:00, 5.124957, 51.68260, False, 91, 17324.2, 59, False, 0
2022-09-19 09:00:43+02:00, 5.124957, 51.68260, False, 91, 17324.2, 59, False, 0
2022-09-19 10:00:43+02:00, 5.124957, 51.68260, False, 91, 17324.2, 60, False, 0
2022-09-19 11:00:46+02:00, 5.124957, 51.68260, False, 91, 17324.2, 60, False, 0
2022-09-19 12:00:48+02:00, 5.124957, 51.68260, False, 91, 17324.2, 60, False, 0
2022-09-19 13:00:52+02:00, 5.124957, 51.68260, False, 91, 17324.2, 60, False, 0
2022-09-19 14:00:44+02:00, 5.124957, 51.68260, False, 91, 17324.2, 61, False, 0
2022-09-19 15:00:34+02:00, 5.125942, 51.679128, True, 85, 17324.3, 61, False, 0
2022-09-19 16:00:48+02:00, 5.124957, 51.68260, False, 86, 17330.7, 59, False, 0
2022-09-19 17:00:52+02:00, 5.124957, 51.68260, False, 86, 17330.7, 59, False, 0
2022-09-19 18:00:59+02:00, 5.124957, 51.68260, False, 86, 17330.7, 59, False, 0
2022-09-19 19:00:47+02:00, 5.124957, 51.68260, False, 86, 17330.7, 59, False, 0
2022-09-19 20:00:41+02:00, 5.124957, 51.68260, False, 86, 17330.7, 59, False, 0
2022-09-19 21:00:44+02:00, 5.124957, 51.68260, False, 86, 17330.7, 59, False, 0
2022-09-19 22:00:43+02:00, 5.124957, 51.68260, False, 86, 17330.7, 59, False, 0
2022-09-19 23:00:40+02:00, 5.124957, 51.68260, False, 86, 17330.7, 59, False, 0
2022-09-20 00:00:45+02:00, 5.124957, 51.68260, False, 86, 17330.7, 59, False, 0
2022-09-20 01:00:41+02:00, 5.124957, 51.68260, False, 86, 17330.7, 59, False, 0
2022-09-20 02:00:43+02:00, 5.124957, 51.68260, False, 86, 17330.7, 59, False, 0
2022-09-20 03:00:42+02:00, 5.124957, 51.68260, False, 86, 17330.7, 59, False, 0
2022-09-20 04:00:46+02:00, 5.124957, 51.68260, False, 86, 17330.7, 59, False, 0
2022-09-20 05:00:43+02:00, 5.124957, 51.68260, False, 86, 17330.7, 59, False, 0
2022-09-20 06:00:46+02:00, 5.124957, 51.68260, False, 86, 17330.7, 59, False, 0
2022-09-20 07:00:27+02:00, 5.091594, 51.684361, True, 88, 17330.7, 59, False, 0
2022-09-20 08:00:47+02:00, 5.124957, 51.68260, False, 91, 17358.9, 53, False, 0
2022-09-20 09:03:11+02:00, 5.124957, 51.68260, False, 91, 17358.9, 53, False, 0

Example summary:

C:\Users\Rick\git\monitor>python summary.py
Period, date      , driven km, charged%, charged kWh, discharged%, discharged kWh, #charges, #drives, km/kWh, kWh/100km, cost Euro
DAY   , 2022-09-17,       0.0,      +4%,         2.8,          0%,            0.0,        1,       0,    0.0,       0.0,      0.00
DAY   , 2022-09-18,       0.0,      +2%,         1.4,          0%,            0.0,        0,       0,    0.0,       0.0,      0.00
WEEK  , 2022 W37  ,       0.0,      +6%,         4.2,          0%,            0.0,        1,       0,    0.0,       0.0,      0.00
DAY   , 2022-09-19,       6.5,      +0%,         0.0,         -1%,           -0.7,        0,       2,    0.0,       0.0,      0.00
DAY   , 2022-09-20,      47.6,      +0%,         0.0,        -14%,           -9.8,        0,       2,    4.9,      20.6,      2.41
DAY   , 2022-09-21,       5.2,     +26%,        18.2,         -1%,           -0.7,        2,       2,    0.0,       0.0,      0.00
DAY   , 2022-09-22,       1.9,      +2%,         1.4,         -1%,           -0.7,        1,       1,    0.0,       0.0,      0.00
DAY   , 2022-09-23,       1.7,     +29%,        20.3,          0%,            0.0,        2,       1,    0.0,       0.0,      0.00
DAY   , 2022-09-24,     407.8,     +37%,        25.9,        -95%,          -66.5,        1,       6,    6.1,      16.3,     16.36
DAY   , 2022-09-25,       0.0,      +8%,         5.6,          0%,            0.0,        0,       0,    0.0,       0.0,      0.00
WEEK  , 2022 W38  ,     470.7,    +102%,        71.4,       -112%,          -78.4,        6,      14,    6.0,      16.7,     19.29
MONTH , 2022-09   ,     470.7,    +108%,        75.6,       -112%,          -78.4,        7,      14,    6.0,      16.7,     19.29
YEAR  , 2022      ,     470.7,    +108%,        75.6,       -112%,          -78.4,        7,      14,    6.0,      16.7,     19.29

 

[CharlesBranch]

I also made a tool to monitor the 12V battery values, your drives, charging/discharging, consumption figures using Bluelink functionality. You can find it here:
Automatic trip administration tools for Hyundai Bluelink users. You can see the fluctuation in the 12V battery in % (warning level is 65%) and also when you have driven.
...

Thanks. That looks pretty cool. I just need to see if I can figure out how to get it working for me.

 

[CharlesBranch]

I took the car to the Columbus, GA dealer on 9-30-22 and told them they could keep it for several days to give them a chance to find the problem. I left them with a log of the history, including the images from the BM3. On 10-3-22 the technician said they could find nothing wrong. I asked him if he had looked at the data in the images I left, and he said they had, but they can only go by the testing they do in their own shop with their equipment. I reminded him that this is an intermittent problem and asked him to contact Hyundai to see what they recommended. He refused to contact Hyundai until they could see the problem themselves. We spoke again on 10-5-22, and he again refused to contact Hyundai. I picked up the car on 10-6-22 and spoke with the service manager. He said they had tested the battery and there was nothing wrong. I reminded him that I had said the problem was probably not the battery itself and was probably the BMS software or firmware. He started repeating the same spiel, so I gave up and just left.


I guess my next option is to contact Hyundai myself at their customer care site (https://www.hyundaiusa.com/us/en/lemon-law-concerns).
Reckon that will result in any action? If not, then I guess the only option is the lemon law once it fails for the third time. I would hate that, because I still really do love the car. But it is not reasonable to expect one to keep a jump starter in the car and use it whenever the system fails again. My wife said she would have no idea how to use a jump starter or even find the battery, and she refuses to drive it.

I have 60 years of experience as a mechanical engineer and I.T. director, and this whole experience is just incomprehensible to me. Whenever any of my staff reported to me that they could not solve a computer or network problem, I always got on the phone with the manufacturer, and most of the time they were able to help resolve such intermittent problems.

But there is one bright spot in all this. Turns out the FM radio apparently is OK after all. The volume control seems to work separately for AM, FM, and SiriusXM, and somehow it had been turned very low for FM.

 

[Mike384p]

What was the final outcome of this? I'm seeing similar 12v battery decay and the it never recharges the 12v unless I drive it or charge it. I've begun leaving the Level 1 charger (at the lowest setting) connected at all times in order to keep the 12v alive. My local dealer had the car for 2.5 weeks and thinks it's the AVN head unit drawing too much (300 ma). Unfortunately the AVN head unit is out of stock, so they cannot replace it until a new one arrives. But still, I think the problem is that the battery is not getting recharged.

 

[CharlesBranch]

There has been no final outcome so far. It sounds like your problem may be slightly different from mine. The problem was intermittent on mine; the traction battery would recharge the 12-volt battery most of the time but failed to do so on five different occasions--four of which I monitored and documented.
I did contact Hyundai, but they would not admit there is a problem. I now go to a charger if the battery is below 20%. That's a real inconvenience--especially after a long trip. The dead 12-volt battery has not recurred since I started doing that. I still think it is a software problem that could be easily corrected if someone at Hyundai would just look at the data that I and others have documented. I still love the car except for this problem, but the 12-volt battery problem and the lack of responsiveness of Hyuydai and the two dealers would keep me from ever buying another Hyundai EV.

And my wife still refuses to drive it for fear of being stranded. I can't really blame her, since she is not mechanically inclined and just expects her car to always work--like it should. I looked again at the Ford lighting and finally was able to drive one. It was nice, but the range was not as good as the Ioniq, and it apparently can't charge as fast. Now I'm looking into the Chevrolet Silverado EV, which apparently is supposed to have a better range.

 

[Mike384p]

Thanks for the reply. My BM2 shows repeating discharge events about 2-3 times/hour. After the discharge event the battery voltage comes back up but not to the level that it was before the discharge event - and the DC-to-DC charger doesn't step in even after the battery gets below 12.5V. Today I purchased a 1 amp battery tender with the hopes that will keep the battery charged enough to be operable. So far, so good. It appears that the charger can bring the battery back to a higher level than before the discharge event. From reading other posts, I think I need a BMS update. I'm also suspicious that the 12v battery was damaged beyond repair by being fully discharged (below 8v) a number of times. I can't figure out why there are so many discharge events - one of my friends thinks that there's a bug in the Hyundai Bluelink server that causes it to ping the car too frequently. I have change my Bluelink password 3 times with no change, so I don't think it's a 3rd party app that's pinging the car. Hyundai needs to step up and solve this problem. I'm betting that all Ioniq

 

[Mike384p]

I'm betting that all Ioniq 5s have this problem but it doesn't show up if you drive it daily. BTW, I bought my Ioniq 5 in March and this started happening in May with less than 1600 miles on it. Sad!

 

[CharlesBranch]

I'm betting that all Ioniq 5s have this problem but it doesn't show up if you drive it daily.

i suspect you may be correct. As best I can recall, all of my 12 volt battery failures occurred after the car had sat unused for a few days. And when I got in after the near misses, the 12-volt battery began charging as soon as I started driving.

 

[electriceddy]

i suspect you may be correct. As best I can recall, all of my 12 volt battery failures occurred after the car had sat unused for a few days. And when I got in after the near misses, the 12-volt battery began charging as soon as I started driving.

Maybe an issue with the ICCU as Hyundia has discovered a power surge that damages transistors, preventing vehicles’ 12-volt battery from recharging.

 

[CharlesBranch]

That may be correct. My car also began to charge very slowly at the EA sites. I took it in for that problem, and I think they replaced the ICCU. So I really don't know for sure if it was that or my avoiding letting it sit for long with less than 20% traction battery charge.

 

[Mike384p]

@electriceddy, thank you for pointing out that it may be the ICCU. There were no DTCs when the dealer tech diagnosed the car. Is it possible that the ICCU is not charging the 12v without a DTC being issued? Also, the 12v charges OK when the car is being driven and when connected to L1, L2, or DCFC. Very puzzling! I uploaded a BM2 scan of an active day notated as follows:
6:50 AM: I had to jump start
6:50-8:55: drove from San Jose to Davis, CA
8:55-9:15: DCFC charged
9:15-10:00: drove Davis to Sacramento
10:00-10:20: short L2 charge
11:20-1:30: re-parked to free up charge station
1:30-2:05: drove to Sacramento to Davis
2:05-3:10: parked
2:05-3:10: drove to Davis to San Jose
5:15-7:30: parked at home
7:30-7:45: drove to pick up dinner
7:45-12:00: parked for the rest of the day

 

[CharlesBranch]

Your recording from 2 to 7 looks a lot like what I called "death spirals" in my car. The 12-volt battery keeps cycling lower and lower until it finally fails rapidly. Clearly the traction battery should be charging the 12-volt battery, but it does not. The next time my traction battery gets below 20%, I might just let it sit for a few days to see if the problem is still there.

 

[CharlesBranch]

Well, we took a trip today, and we made it home with about 4 miles to spare. It was pretty interesting watching the dual between Waze's Miles-to-Home and Ioniq's Miles-Remaining.[ATTACH]20862[/ATTACH] [ATTACH]20863[/ATTACH] This is the closest I have ever come, but I'm told that we actually would have about 15 miles remaining after reading zero. Is that true?
Anyway, this will be the start of the test I mentioned to see if the ICCU replacement for the slow-charge problem also fixed the dead 12-volt battery problem. It may not be an entirely fair test, since it would be pretty reasonable to stop charging the 12-volt battery at 2% traction battery remaining--but not with 20% remaining. I may charge it up to about 15% tomorrow to give a fairer test. Presumably, the BM2 will send me a warning if the 12-volt battery starts another death spiral before then.

 

[Mike384p]

The local Hyundai dealer technician does not seem to have a grasp of how the system is supposed to work. For example, they cannot answer the simple question of "what triggers the system to charge the 12v battery?" I replaced my 12v battery a few days ago with a Duracell AGM battery. It's clear that the original 12v battery could not hold a charge. Since installing the new battery I have not had to jump start the car, but I still see events about 3x per hour that lower the battery voltage by about 0.3v. The difference is that the new battery returns nearly the original voltage before the event. The uploaded BM2 scan shows the events (from midnight to 1:30PM). The 14.8 volt sections are when the car is connected to a L2 charger.