12volt battery problem 2016 kia soul ev

this morning I got into the car and all electrical systems were dead. No screen. no radio. and the car wouldn't start. the car is 10 months old.
so I called the tow truck to bring it to the dealer.
tow truck guy put a battery jumper on the 12v car battery and the car came to life. and worked.
so that was good. I still had him tow it to the dealer so they could diagnose the problem but
now the dealer can't find anything wrong with it. says there are no codes.
could this be an alternator problem?
anyone else have this issue?
also, in these cases when the 12v car battery is dead why in the world doesn't the car use the 27kw battery as a backup?

The big (27 usable kWh / 30.5 kWh total) traction battery runs at very high voltage (~360V) and would fry the traditional 12V car electronics like the radio, lights, instruments, etc.

Because of this voltage difference between the 360V and 12V batteries, the car contains a device called a DC-DC converter, which takes the 360V DC power from the big battery and steps it down to 12V and charges a traditional car battery for startup and accessory usage. This process happens when the car is powered on or when it is charging from an external source.

Just like in a gasoline car, if the 12V battery is depleted the car cannot start. The 12V system is what boots up the car and allows the contactor for the big traction battery to be engaged and the DC-DC converter to come online, replenishing the traditional 12V car battery. The big battery only provides power for the drive motor and the AC compressor and heating element, which all run at 360V.

Anything that could deplete the 12V battery in a gas car would do the same in a Soul EV (and most other EVs and PHEVs). Leaving an interior light on, headlights on, door ajar, etc. Furthermore, a defective 12V battery will render the EV inoperable just as it would a gasoline car.

Some upcoming models like the Hyundai Ioniq are doing away with the 12V battery by just relying on the 12V output from the DC-DC converter for startup and accessories, but our Souls do not have this feature and therefore require a charged and properly functioning traditional 12V car battery to start up and run.

mtndrew1 is spot on.

The one thing I would add is that there was a dealer tech note to flash a new firmware to the DC-DC converter so that it charged the 12V more often and tried to avoid getting a flat 12V battery. Ask your dealer to check that your car is up to date with this.

mtndrew1 said:

Some upcoming models like the Hyundai Ioniq are doing away with the 12V battery by just relying on the 12V output from the DC-DC converter for startup and accessories, but our Souls do not have this feature and therefore require a charged and properly functioning traditional 12V car battery to start up and run.

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The Ioniq EV that I saw does have a 12V battery. The Ioniq Hybrid does too. I have not seen the PHEV yet.

I killed my 12v battery the very first week I had my Soul. Left the Nav on, I think. Lame, but an easy jump since I have another car. I would add that probably half the Soul EVs we tried to start in the dealer's lot had dead 12v batteries when I was shopping. Not very encouraging.

JejuSoul said:

mtndrew1 said:

Some upcoming models like the Hyundai Ioniq are doing away with the 12V battery by just relying on the 12V output from the DC-DC converter for startup and accessories, but our Souls do not have this feature and therefore require a charged and properly functioning traditional 12V car battery to start up and run.

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The Ioniq EV that I saw does have a 12V battery. The Ioniq Hybrid does too. I have not seen the PHEV yet.

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Oh interesting, thanks for correcting me!

I wonder which car am I thinking of then? I'm relatively certain that a newer model is doing away with the 12V battery but perhaps I just misunderstood a press release somewhere along the way.

buddhaauthor said:

I would add that probably half the Soul EVs we tried to start in the dealer's lot had dead 12v batteries when I was shopping. Not very encouraging.

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I have heard lots of reports like this about the 12V battery dying if left without running the car. It is why I would switch off the power when going on vacation for more than a few weeks. Note this is nothing to do with the fact that this is an electric car. It could happen to any car.

There are also lots of reports of the 12V battery failing to be recharged properly when the car is running. This is why the service advisory fix is recommended for people having trouble with the 12V battery. This is a different issue to the one above and it is relevant that this is an electric car. Mtndrew1 thanks for providing a good explanation for all this in your post above.

About the Ioniq 12V battery. There is an article on the Hyundainews site that says just what you are saying. IONIQ Electric
The problem is that I can see the lead-acid auxiliary 12V battery in the picture of an Ioniq EV above. I think it is the Ioniq Hybrid that has no 12V battery. I was wrong when I said I had seen it on this version. Here is a picture of an Ioniq Hybrid.

JejuSoul said:

mtndrew1 said:

Some upcoming models like the Hyundai I oniq are doing away with the 12V battery ....

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The I oniq EV that I saw does have a 12V battery. The I oniq Hybrid does too. I have not seen the PHEV yet.

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Then I changed my mind because of this:- http://www.hyundainews.com/us/en/models/ioniq-electric/2017

www.hyundainews.com said:

In addition, the lead-acid auxiliary 12V battery found in competitors’ hybrid models has been omitted, resulting in an approximate 26-pound reduction in weight.

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Amazing how long fake news can last. Although this nonsense did come from an official Hyundai USA press release. Presumably they looked in the front of an
I oniq Hybrid at a car show and reported that it had no 12V battery. We have continued to believe this, without ever checking to see if it is true.

It isn't true. The Hybrid 12V battery is at the back.



From a YouTube posted a year ago in Jan 2016 - Hyundai I oniq Hybrid Launch Review (English Subbed)
https://www.youtube.com/watch?v=kmSdHewNoow