My Kona 64kwh called the emergency services the other day. The next day the microphone for handsfree and voice control stopped working.

I researched, to find that both these things have been signs of an impending auxiliary battery failure. In most cases the owners either gave it a quick jump start and all was ok, or went back to dealers who either discharged and charged the 12v, or replaced it. All was good after this too.

A few causes of why the 12v battery would drain were hypothesized: a water short in door detection contacts, a software module that doesn't close on shut down, open tailgates, etc.

Most people said that if the 12v battery was low, then a couple of hours in utility mode would sort it.

So... Being "pre battery fail" I am trying to assess what is going on and how I can avoid the fail.

I have used car scanner to look at battery current, aux battery current and aux battery voltage.

I have left the car in utility mode for an hour, but microphone still not working.

The current aux battery voltage is 13.3V in utility mode. When the car is turned off it drops to 12.5V.
The aux battery current when the car is turned on is -32.7A when the car is warm.
However, after a while (around 40 mins or so) it starts to alternate from +32.7 to -32.7 (a few times a second).
All the time, the main battery is between 0.5A and 1A.

If I turn the car off, it will go back to -32.7A (this makes no sense to me as this suggest it's charging) as the main battery drops to 0A. I have not managed to monitor it having turned off and locked it.

Does everything seem normal? Or am I heading for a battery fail?

I believe that Car Scanner is using the incorrect formula for 12v current, so you can't use that for any fault diagnosis.
I suggest the handsfree mic issue would be best diagnosed by a dealer.

 

I believe that Car Scanner is using the incorrect formula for 12v current, so you can't use that for any fault diagnosis.
I suggest the handsfree mic issue would be best diagnosed by a dealer.

Further to my comment, I believe that the Car Scanner parameter which gives a much more acceptable value for the aux battery current is identified as "Auxillary Battery Current var. 2".

An interesting and informative discussion about the "correct" formula for giving the current is in this thread Tracking the 12v Battery with OBD2

And regarding the car correctly topping up the aux battery from the HV battery, a number of owners have found that a small bluetooth monitor is very informative - see for example this thread 12v Battery issues (again!)

 

However, after a while (around 40 mins or so) it starts to alternate from +32.7 to -32.7 (a few times a second).

Are they using a 16 bit integer to store the current in milliamps...? -32768 to +32767 looks like an overflow to my engineering brain.

it will go back to -32.7A (this makes no sense to me as this suggest it's charging)

Unless they're incorrectly using a signed integer... -32768 would be 0 if it was unsigned.

Could be bad programming, could be coincidence...

 

Are they using a 16 bit integer to store the current in milliamps...? -32768 to +32767 looks like an overflow to my engineering brain.

Unless they're incorrectly using a signed integer... -32768 would be 0 if it was unsigned.

Could be bad programming, could be coincidence...

I believe that Car Scanner is using the incorrect formula for 12v current, so you can't use that for any fault diagnosis.
I suggest the handsfree mic issue would be best diagnosed by a dealer.

The microphone / dead battery relationship is quite a phenomenen. The pattern is; mic stops working, then 12-36 hours later, battery dies. A few posters also mention that the SOS function self-activates.

Not all dead batteries have this pre-symptom, and not all dead mics are necessarily a precursor, but there's definitely a huge correlation, and it's the most likely cause of the mic being dead in my eyes...

My question is really, how can I tell the real health of the 12V battery using the OBDI data?

Here are some of the threads with lots of dead mics and batteries.

European 2020 Electric EV Premium - Mic has stopped working

Hi, Out of the blue the microphone in the car has stopped working (or is on some sort of permanent mute), as a result voice recognition does not work, nor can anybody hear me on voice calls through the car. I have googled it and a lot of what came up related to ioniq's and flat 12v batteries...

www.hyundaikonaforum.com

Microphone not working

Received 2020 model few days ago and the microphone seems to have stopped working. No one can hear me speaking including the built-in assistant or Android Auto assistant. Any ideas? I've unpaired my phone and tried again but nothing changed. I'm sure it worked because I used it on the first...

www.ioniqforum.com

 

OK, well there we go... 12V battery dead this morning - as predicted.

Car opened, although power mirrors didn't fold out. Just clicked when I tried to start it. Fortunately, had bought an emergency jump start battery. Although top tip, don't keep it under the floor in the boot, because the boot won't open if the 12V is dead. I got mine out via the rear seat. Drove car and left it on. It operates ok, but the mic is still non functional. Back to the dealer...

 

OK, well there we go... 12V battery dead this morning - as predicted.

Car opened, although power mirrors didn't fold out. Just clicked when I tried to start it. Fortunately, had bought an emergency jump start battery. Although top tip, don't keep it under the floor in the boot, because the boot won't open if the 12V is dead. I got mine out via the rear seat. Drove car and left it on. It operates ok, but the mic is still non functional. Back to the dealer...

Yes to the dealer looks like your best option.
Out of interest have you fitted a dashcam , or do you leave an OBD adapter always plugged in? These are both possible drains enough to alert the car into a semi active state, which consequently can draw significant aux battery current...
And apparently any of the rear hatch /doors / front bonnet not quite latched can also wake up the car.