If you've had a dead 12v battery please respond

Has your 12v battery died for no reason?

  • Yes

    Votes: 26 51.0%

  • No

    Votes: 23 45.1%

  • Yes, but I left something on/it was my fault

    Votes: 2 3.9%
  • Total voters
    51
My turn in the barrel today. I left the Aerovironment EVSE plugged in last night. After charging, it went into the usual death spiral and drained the 12v battery. No problem booting it up with my little power pack from Harbor Freight. I am glad I remembered to store it up against the back of the rear seat, since without the 12v battery the trunk won't open.
 
Toolworker said:
My turn in the barrel today. I left the Aerovironment EVSE plugged in last night. After charging, it went into the usual death spiral and drained the 12v battery. No problem booting it up with my little power pack from Harbor Freight. I am glad I remembered to store it up against the back of the rear seat, since without the 12v battery the trunk won't open.
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How long has this been going on? You've had your car for quite a while.
 
Wildeyed said:
How long has this been going on? You've had your car for quite a while.
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Short answer: Two years, two months and two Konas.

Long answer: I got the 2020 Kona EV in January 2020. The next month, the battery died for the first time. After Hyundai road service jumped it, I bought the booster pack.

After a year and a half, one 12v battery replacement, and multiple futile attempts to get Hyundai to admit to the problem which I had meticulously documented, the Hyundai case agent whom I had acquired somewhere along the way strongly hinted that I should do a lemon law buyback. I guess he was as tired of the problem as I was. I did the math, got into the queue early during the HV battery recall and went through the process. After thoroughly evaluating the other options, I bought a 2021 Kona EV.

Which has the same problem. I'm kind of used to it by now.

It's an interaction between the Kona and this specific model EVSE. Other EVSEs display anomalies, but this is the one that intermittently creates the death spiral.

I don't drive that much. I only charge every week or two and unplug the EVSE the next day. This is maybe the third or fourth time it's happened in 9 months.
 
I don't know whether to point the finger at the charger or the vehicle. I've seen a loop where the EVSE starts to charge the car, then it gets some signal from the car, stops charging, then ten seconds or so later it repeats. All this keeps the car awake on 12v power without charging, and within a few hours it's dead.

I've seen another loop where the 12v charging starts and stops as part of this process (Hyundai logo LED and charging port turn yellow).

My bet is that it's the Hyundai algorithm that's doing something unexpected, but I can't be sure.

Another way to kill the battery is to ping Bluelink repeatedly. The car wakes up for about 6 minutes during which the 12v battery is running it. That eats up about 1% of the battery capacity per ping.
 
Weird that you, and some others keep having this problem. I keep an eye on my 12V with the battery monitor, and never a problem. And you have had that problem with both cars. I wonder if you are doing something different that may be causing the issue. Not saying it isn't a legitimate problem. But what is it that you are doing that I and others are not.

One thing is that I don't use an EVSE at home to charge my car. And you leave it plugged in for an extended time? Do you use a BM2? That should tell you when your battery gets drained? And which EVSE do you use?

I do use Bluelink, not a lot, but have never seen it drain my battery.

Is the car in your garage close to where your FOB might be. Or is your phone bluetooth active with the car when you are not in it?
 
R P said:
Weird that you, and some others keep having this problem. I keep an eye on my 12V with the battery monitor, and never a problem. And you have had that problem with both cars. I wonder if you are doing something different that may be causing the issue. Not saying it isn't a legitimate problem. But what is it that you are doing that I and others are not.

One thing is that I don't use an EVSE at home to charge my car. And you leave it plugged in for an extended time? Do you use a BM2? That should tell you when your battery gets drained? And which EVSE do you use?

I do use Bluelink, not a lot, but have never seen it drain my battery.

Is the car in your garage close to where your FOB might be. Or is your phone bluetooth active with the car when you are not in it?
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You'd have to use Bluelink 100 times to drain your battery.

I do use a BM2 and have lots of graphs of the death spiral, and a couple of videos. The EVSE is an Aerovironment EVSE-RS. It's no longer made, and the company's called something else now. The car is 60 feet away from the house. I no longer keep the EVSE plugged in for extended times.

Many other Hyundai owners - not just Konas - have had 12v batteries die in other ways. I suspect there is a flaw in the sequence of operations the Kona performs when it prepares for 12v charging. In that process, it sends signals to the EVSE, which my particular model responds to in a way that causes the death spiral. I've looked at the 12v charging process using the Hyundai EVSE cord at 120v and 240v, and observed other anomalies, but not the death spiral.

I can't rule out an EVSE hardware flaw or design issue, but I think it's more likely a mismatch in the sequence of operations, communication and timing between the Kona and this particular model of EVSE, probably if HV charging ends when the Kona is starting to do 12v charging.
 
Does the death spiral just happen with the EVSE, and only when left plugged in for extended times? Have you tried another EVSE to see if it does the same thing?
 
Even though we hear a lot about 12 volt failures on forums like these I'm pretty sure they are still a very small proportion of Konas in the wild. It makes sense to me that the charging station, the one variable from owner to owner, bears some of the responsibility for the "death spiral" that you've documented. Delete that and see if the pattern changes. Too bad you have to deal with it whatever the root cause.
 
This morning, my 12 V was dead. Second time in a year. Scheduled climate wasnt running when I entered the garage, so I had a feeling it would be toast.
Trying a start resulted in click, click,click as the high voltage contactors tried to engage, I'm thinking.
I leave the car doors unlocked when parked in the garage, maybe this is keeping the car awake to report my car is in danger of being stolen?
Anyways, pulled out my portable booster pack, and it started up. When I got to work, I left the car in utility mode for 4 hours.
Thursday I'm getting the dealer to switch tires and fix the stupid plastic handle in the hatch door, so I'll get them to check the 12V battery...again.
Of course, the last time it died, they said the battery was in good shape. Uh huh, sure.
 
My 2019 Kona 12V battery died the first time back in Nov 2021 after I drove to Walmart to pick up something quick and the car could not start when I return to the parking lot. It was so embarassing to have my EV towed in front of all the ICE car users.... At that time I was not aware I could have jumped the battery and start the car. After towing to hyundai dealership they claim the 12V battery died and was out of warranty so I had to pay for a new battery. Now 3 months later in Feb 2022 when my car what still plugged in to my home charger the same thing happend. the 12V batteyr died and car would not start. I had CAA come and they were able to jump stat the battery for me. Brought the car to Hyundai dealership and they ahd not idea what the issue was except admitting that the 12Vbattery was drained. They tried to blame on the dash cam that I connected to the car was draining the battery but I have been using the dash cam for 3 years and it ahs been fine. So is it something within the car either software or hardware related that is draining the battery? If so how should this be resovled as the dealership keep inssiting they are not able to identiry the issue....
 
My 6000km old Kona had all sorts of lights show up in the dashboard this week, schedule an appt with Hyundai and they determined my 12V battery was ‘weak’ because I didn’t drive enough - morons….they didn’t replace it, instead gave it a boost and boom all warning lights were gone.

I am seriously considering buy the 121 battery from Costco - some have said this permanently resolves all issues
 
JBX said:
My 6000km old Kona had all sorts of lights show up in the dashboard this week, schedule an appt with Hyundai and they determined my 12V battery was ‘weak’ because I didn’t drive enough - morons….they didn’t replace it, instead gave it a boost and boom all warning lights were gone.

I am seriously considering buy the 121 battery from Costco - some have said this permanently resolves all issues
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Well, you know, if you don't drive enough then the alternator doesn't have a chance to charge it. /s
 
I had Dead 2022 Kona EV within 5 days of purchase and 400 Miles Driven. Strange thing is I noticed Bluelink not working initially. But rest was fine and car was charging. I though bluelink is not working due to poor cellular reception and did not pay much attention to that. I later drove the car fine, however bluelink still failed to work. And upon rethen car would not charge at all. Rest worked fine. Cabin lights were not dim. I then drove again to Public L2 Charger. Still car would not charge and bluelink did not function. There was a red plug Icon on dash. I still left the car plugged in overnight to L1 charging. Yesterday morning I removed the charger and kept the car completely off. Today I wanted to try charging one more time before going to dealer, and the 12V battery was completely dead.

I did not try Jumping, but I had car flatbedded to dealership. Anyone had this experience where at some point car was able to drive but not charge due to what possibly could be 12V battery failure? I will follow up with the post after I get the car back.
 
R P said:
Does the death spiral just happen with the EVSE, and only when left plugged in for extended times? Have you tried another EVSE to see if it does the same thing?
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In my case my Kona was not plugged in when it first happened. I drove to Walmart and went inside for less than 15 minutes, wehn I return the 12 V battery died and I could not start. At that time my car was only 2.5 years old and I had over 60,000 KM on it so I drove a lot have ensure it is properly charged. Somehow within that 15 minutes inside Walmart my 12 V battery got drained...
 
Toolworker said:
You'd have to use Bluelink 100 times to drain your battery.
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A German owner on GoingElectric.de reported a similar death spiral recently. It turned out to be his "OpenWB" EVSE polling the car every 30 min over BlueLink for the SoC.

Batterie1.webp
 
R P said:
Does the death spiral just happen with the EVSE, and only when left plugged in for extended times? Have you tried another EVSE to see if it does the same thing?
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Yes, only with the EVSE plugged in. I unplug it when I'm in the garage and charging is finished, but it can happen just plugged in overnight. The EVSE (charge cord) that came with the car doesn't seem to do it, but I have seen 12v charging anomalies with it plugged in. Maybe I should leave it plugged in for the next few months and see what happens.

KiwiME said:
A German owner on GoingElectric.de reported a similar death spiral recently. It turned out to be his "OpenWB" EVSE polling the car every 30 min over BlueLink for the SoC.
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That shouldn't kill it unless the EVSE is keeping the car awake. It only stays awake on its own for about 6 minutes. Maybe the polling for SoC causes additional battery draw, or maybe the 12v charging algorithm decided not to charge for a while despite the low battery.
 
cthindi said:
I had Dead 2022 Kona EV within 5 days of purchase and 400 Miles Driven. Strange thing is I noticed Bluelink not working initially. But rest was fine and car was charging. I though bluelink is not working due to poor cellular reception and did not pay much attention to that. I later drove the car fine, however bluelink still failed to work. And upon rethen car would not charge at all. Rest worked fine. Cabin lights were not dim. I then drove again to Public L2 Charger. Still car would not charge and bluelink did not function. There was a red plug Icon on dash. I still left the car plugged in overnight to L1 charging. Yesterday morning I removed the charger and kept the car completely off. Today I wanted to try charging one more time before going to dealer, and the 12V battery was completely dead.

I did not try Jumping, but I had car flatbedded to dealership. Anyone had this experience where at some point car was able to drive but not charge due to what possibly could be 12V battery failure? I will follow up with the post after I get the car back.
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It did turn out to be 12 V failure. I was trying to confirm Aux battery saver is on as is documented in the user guide and confirm whether the mode was Auto or Cycle. I could not find it any of the menu's. Anyone knows access to Auxiliary Battery saver set up in 2022 Kona EV SEL?
 
cthindi said:
I could not find it any of the menu's.
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Well it doesn't surprise me Aux. battery saver reference has not been removed from the user guide, probably a low priority and oversight on Hyundai's part.
The ability to enable or disable that option was removed with software update mid 2020.
Verify VCULDC version software has been updated or included to C00D111 at the dealer ;)
 
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