[Arob]

Was it plugged while it was sitting for a few days?

Yes, I follow the ABC rule (Always be Charging).

 

[AckyT]

Last week I went to my Ioniq 5 to check my mileage for insurance renewal. The car opened as normal.
When I attempted to start the car, I got a message on screen to press start key with the key fob. Not had it before.
The screen went on briefly and showed a warning about the 12v battery. It quickly went off. I tried to start the vehicle again - but nothing happened.
I tried to leave the car but the handles would not work. It was a very sunny morning and warm in the car. After trying handles a few times without success I tried to open the windows. Nothing. Everything was dead.
I did not have my mobile with me and had left house without telling my wife where I would be.
I began to panic and our car was not visible from any road to alert passers by. The temperature raised in the car and I began to hyperventilate.
After around 20-30 minutes my wife came out of the house to find out where I was. By this time I was in a bit of a state. She sought help from my neighbour who immediately called the Fire Brigade & Ambulance services.
When they arrived I managed to tell them of the brief warning for the 12v battery. The Fire Service were prepared to break windows but my neighbour had a spare 12v battery which fortunately could be hooked up to my car as I was able to release the bonnet. ( Good job that wasn’t electric) After hooking up to the battery they electrics came on and the doors could be opened.
I rang Hyundai when I overcome the shock. They said I had to contact Hyundai Assist who called out the AA.
The AA done quick test on battery and could not detect the issue.
The car was taken to Hyundai. After a day they contacted me to say the cannot find any issues on their diagnostic systems and said the 12v battery was OK.
I told them that this could have been a fatality if I had not been found, as the temperature in the car had raised dramatically , as asked them to provide information on escaping from the car when all electrics went dead.
The answer from them was that a driver would have to climb over front and back seats and then release the tailgate by sliding a flat instrument into the manual release hole on the inside of the tailgate. I’m 71 years of age with limited mobility.

So sorry to go on so much but I want to know if anyone else has had a similar event.
I’m waiting to hear back from Hyundai Customer services who I have registered my concern and complaint with them. I really don’t think they are taking this very 😦

Quick update. I chased up Hyundai UK Customer Services since no one called back. I have a case manager who is responsible for investigating this issue. I’m informed that the case has been Escalated to Management Level. I informed them of the helpful comments received on this Forum and said that Hyundai must try to replicate the situation I experience and come up with answers and solutions. I shall keep you all posted.

 

[Arob]

Nope. The car is designed to maintain the 12v battery both when being driven or shut down (as long as HV battery SOC is > 10%)

OK, then you explain to me...while plugged in to 120V L1 for a few days without driving, it dipped to 69%, but after about 40 miles of driving, it went up to 91%.

I have seen the dash light on occasion while plugged in, but it seems odd the 12V maintenance isn't more proactive given the number of complaints.

On my previous EV (Chevy Bolt), every time it reached target charge level for the HV battery, it would continue to draw a small amount of energy (<1kW) for 4 hours running 12V battery maintenance and HV battery diagnostics (due to the fire recall). I didn't monitor 12V at all, GM did a great job of maintaining the AGM battery that came stock. When I sold the car 6 years later to my brother at 110K miles, it still had the original 12V, and when he gave the car to his son a few months ago at 7+ years old and over 125K miles, he had the car looked over by his local Chevy dealer, the 12V still tested 100% healthy.

Maybe the GM/Hyundai partnership will yield something in the area of 12V battery maintenance? It sure seems Hyundai could use some help in this area!

 

[Ionhorse]

That sounds like the child safety lock was engaged. I recall seeing a review somewhere that complained that the button to engage this feature was too easy to accidentally push on pre-2025 Ioniq 5s, but it's slightly improved in that respect for 2025 (but it can still be accidentally engaged). Here's a Hyundai video about this feature:

Exactly! That button is too easy to push.

 

[JerryP]

JerryP, what do you think about one of these?

Amazon.com: Auto Battery Monitor BM2 Bluetooth 4.0 12V Device Car Battery Tester : Automotive

Buy Auto Battery Monitor BM2 Bluetooth 4.0 12V Device Car Battery Tester: Battery Testers - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

Looks just like the two I have. Works great.

 

[hpark21]

OK, then you explain to me...while plugged in to 120V L1 for a few days without driving, it dipped to 69%, but after about 40 miles of driving, it went up to 91%.

I have seen the dash light on occasion while plugged in, but it seems odd the 12V maintenance isn't more proactive given the number of complaints.

Maybe the GM/Hyundai partnership will yield something in the area of 12V battery maintenance? It sure seems Hyundai could use some help in this area!

MAYBE, just MAYBE, that max try threshold (5x) got hit during 1 week? I BELIEVE while the car is turned off (maybe not plugged in), the HV battery will engage and charge the 12V battery. BUT I think it tries like 5x or something like that until it gives up recharging in case the 12V battery is bad and not keeping charge - is it right or wrong? I do not know but I believe this is the case.

 

[Son of swen]

Well, that was easy. Here are more details than anyone needs, step by step.

2024 Ioniq 5 RWD LR SEL. US model.

1. I got in the car and put it in READY.
2. I opened the driver's window. I shut off the car.
3. I released the hood.
4. I got out and closed the door.
5. I reached in and locked the doors with the button on the driver's armrest.
6. I took my fob inside, just for insurance although I was sure it wouldn't be a factor.
7. I lifted the hood and popped the cover off the battery.
8. I disconnected the negative clamp from the battery post and moved it away from the post.
9. I reached in the open driver's window and pulled the inside driver's door handle
10. One ping pull only, Vasily. One pull only, please.
11. The door opened.
12. I closed the door.
13. The outside handles all stayed in the retracted position.
14. I opened it again using the inside handle.
15. Again, the outside handles stayed in the locked position.
16. Worked every time. You can feel and hear the mechanism moving.
17. I put it all back together.

There is no logic in making it so the door ONLY opens electrically when that makes it so obviously unsafe.

I will most likely get in trouble for this, but it may relate to the story............or a rendition of:

The misinformation effect demonstrates how post-event information can distort or alter an individual's memory of an original event, leading to false recollections. A classic example involves eyewitness testimony where leading questions or misleading information can cause people to incorrectly remember details of an event.

 

[JerryP]

It maintains the 12v when off exactly as designed. Never had a problem.

Nor have I, but others have and I've had one dead battery and one close call in one year of ownership. There are tons of discussions on that topic around here. Imho, it's usually because either the 12V is failing and the charging system isn't keeping up, or there's some extra load on the 12V that shouldn't be there.

The car waits a long time before charging the 12V and doesn't always charge long enough to bring it back up to anything close to full charge. But when being driven, it keeps a continuous eye on the 12V and tops it off almost continuously. When charging the HV battery, it maintains a steady charge on the 12V.

 

[Arob]

MAYBE, just MAYBE, that max try threshold (5x) got hit during 1 week? I BELIEVE while the car is turned off (maybe not plugged in), the HV battery will engage and charge the 12V battery. BUT I think it tries like 5x or something like that until it gives up recharging in case the 12V battery is bad and not keeping charge - is it right or wrong? I do not know but I believe this is the case.

Might be. But nevertheless, Hyundai knows there is a problem with 12V batteries, you would think they would focus a little more attention on maintaining it.

 

[Coastal]

OK, then you explain to me...while plugged in to 120V L1 for a few days without driving, it dipped to 69%, but after about 40 miles of driving, it went up to 91%.

I have seen the dash light on occasion while plugged in, but it seems odd the 12V maintenance isn't more proactive given the number of complaints.

The topic has been debated endlessly on these forums since the first I5's were released.

Many (me included) like others in this thread have seen no issues with the 12V. I have a BM2 connected and can see the 12V being maintained whether the cars is parked for a couple of weeks at the airport or in the drive (unplugged into L1/L2), driven regularly or left plugged into L1/l2 for several days. For the first 18 months of ownership I just charged (L1/L2//L3) when HV battery dropped to 20 - 30% recently I plug in every night to charge to 80%.

It's always the same if the (unloaded) 12V battery goes to around 12.6V it gets recharged. If left undriven for around 3 days it goes into a deep sleep requiring very few 12V top ups.

However you and others see different. Do I recall correctly your 12V issues were soon after you got the car? Maybe the car had sat on the lot for many months before you bought it and the 12V had not been maintained? Other have had issues after getting work on the car and the 12V had not been maintained when disconnected. Other had accessories (dash cams etc) connected. Others maybe something else?

My car is approaching two years old (next month) with 21k miles and the original OEM battery is still being maintained correctly. When I need to replace it I will get an AGM battery (which is what Hyundai used in development) but for now the BM2 plots show it is being maintained correctly.

Here is a couple of recent plots.

This one the car parked at the airport for a couple of days

Level 2 charging for just over an hour at midnight and then the 12V got charged at 7PM

Edit - one more plot. 1 week at the airport last September

 

[tbitson]

I carry a portable 12V battery jumper pack inside the car just in case I have an issue like this.

I wonder if there’s a location inside the car to connect the battery jumper pack? Maybe near a fuze box or something? Since you don’t need high current to “start” the car, it might be possible to power up the 12V system from within.

Something to look into…

 

[Arob]

However you and others see different. Do I recall correctly your 12V issues were soon after you got the car? Maybe the car had sat on the lots for many months before you bought it and the 12V had not been maintained? Other have had issues after getting work on the car and the 12V had not been maintained when disconnected. Other had accessories (dash cams etc connected). Others maybe something else?

Not me, Jerry had the issue in his first week with the car.

Mine came at around 10 months in, and it wasn't a 12V issue per se. Mine seemed to go into a deep sleep state, unresponsive till we hit it with a jump pack and it came back to life instantly, blaring horns and all to announce its return to the world. When I tested the 12V, it was 100%, it wouldn't even take a charge (we tried that before the jump start jolt). I still am unsure of what caused it to go into a deep sleep, but I was working in the garage with the fob in my pocket, maybe all the false positives from unlocking the doors caused it to ignore the fob?

I am now 14 months in, and the 69% the other day was the first time I noticed low SOC on the 12V. But then I wasn't looking before using @andyfase Scriptable app. It has been at 91% for the last two days, after driving about 40 miles on the day it was at 69%. I have seen it up in the 98-99% range prior.

So, I am not so worried about my 12V, but may just drop an AGM in as a precaution. No rush though.

 

[GregBrew]

It maintains the 12V when off ... after a fashion. The graph from my BM2 gets pretty low sometimes before the car's charger kicks in.

Mine only gets down to 12.6V before the ICCU recharges it. About once a day.

Note that I replaced the four month old POS OEM factory flooded 12V PbA battery with a MallWart AGM PbA a couple of months ago. It doesn't deplete nearly as fast as the OEM.

 

[AckyT]

The topic has been debated endlessly on these forums since the first I5's were released.

Many (me included) like others in this thread have seen no issues with the 12V. I have a BM2 connected and can see the 12V being maintained whether the cars is parked for a couple of weeks at the airport or in the drive (unplugged into L1/L2), driven regularly or left plugged into L1/l2 for several days. For the first 18 months of ownership I just charged (L1/L2//L3) when HV battery dropped to 20 - 30% recently I plug in every night to charge to 80%.

It's always the same if the (unloaded) 12V battery goes to around 12.6V it gets recharged. If left undriven for around 3 days it goes into a deep sleep requiring very few 12V top ups.

However you and others see different. Do I recall correctly your 12V issues were soon after you got the car? Maybe the car had sat on the lot for many months before you bought it and the 12V had not been maintained? Other have had issues after getting work on the car and the 12V had not been maintained when disconnected. Other had accessories (dash cams etc) connected. Others maybe something else?

My car is approaching two years old (next month) with 21k miles and the original OEM battery is still being maintained correctly. When I need to replace it I will get an AGM battery (which is what Hyundai used in development) but for now the BM2 plots show it is being maintained correctly.

Here is a couple of recent plots.

This one the car parked at the airport for a couple of days


View attachment 58926

Level 2 charging for just over an hour at midnight and then the 12V got charged at 7PM

View attachment 58927

Edit - one more plot. 1 week at the airport last September

View attachment 58928

Suggest you read the full thread of this posting before you trivialise the importance of it. There may have been lots of past posts about 12v issues and I’m pleased that you have had no issues.
However, The fact is that I could have died in my car because the 12v battery, for some unknown reason went down, and prevented everything working (Including door handles, windows , horn etc etc. I want to understand WHY.
I had no means of escape, no mobile to get assistance.
Manufactures should be held accountable for such safety issues. I hope you never find yourself in a similar position.

 

[Coastal]

Suggest you read the full thread of this posting before you trivialise the importance of it. There may have been lots of past posts about 12v issues and I’m pleased that you have had no issues.
However, The fact is that I could have died in my car because the 12v battery, for some unknown reason went down, and prevented everything working (Including door handles, windows , horn etc etc. I want to understand WHY.
I had no means of escape, no mobile to get assistance.
Manufactures should be held accountable for such safety issues. I hope you never find yourself in a similar position.

Sorry I was referring to @Arob's comment on whether the 12V gets maintained (which has been endlessly discussed before) not the horrific experience you went though. I should have been clearer. Hopefully you will get an explanation from Hyundai UK.

@JerryP Has demonstrated (in post #19) that in US the door can be unlocked from the inside with a dead 12V. Likewise @David J. has shown (in post #47) in Australia it can be unlocked from inside with dead 12V. I don't think some of the later posters have picked up it seems to vary by market.

It does seem very strange that the UK is dangerously different. I am really surprised that would even be legal in the UK - it is indeed a death trap and needs to be urgently addressed by Hyundai.

Again sorry if it sounded like I was trivializing your experience. That was absolutely not my intention.

 

[JerryP]

Not me, Jerry had the issue in his first week with the car.

Yep. That was me. It really had me concerned for a while and I think I made quite a bit of noise around here when it happened as I tried to sort out what was going on. When I installed my BM2 a few days later, I noticed that the positive battery terminal clamp was loose.

BTW, yesterday was the one year anniversary of buying the car. The incident happened almost exactly a week after I got it.

Then about three weeks later we were on our way home from Iowa. It was plugged in to L1 at an Air B&B overnight. I don't remember what caught my attention the next morning, but I checked and it was down to 12V. It started up just fine.

I have not had any events since then, but the battery voltage does fade more quickly than I'd like, so I'll be getting an AGM before we take our big summer road trip.

So we're dealing with two issues. One being a combination of using a junky wet battery rather than AGM and also having less than optimal but usually adequate 12V charge state maintenance. The other scarier issue is that apparently Hyundai has deleted the mechanical linkage for the door latches in the UK and possibly some other places for all we know, which should not be legal. [Edited to fix omission of UK being the only place we know of so far with the deletion plus a BUNCH of typos.]

 

[Arob]

The other scarier issue is that apparently Hyundai has deleted the mechanical linkage for the door latches, which should not be legal.

I think your test says differently, at least for the US market, and at least one Aussie has chimed in confirming the same there.

So, the issue really seems to be a UK or EU one?

 

[JerryP]

Thanks. I meant to say UK. I'll fix that.

 

[Arob]

Thanks. I meant to say UK. I'll fix that.

I edited your edit, the Aussie (post 47) claims the latch is mechanical down unda.

 

[JerryP]

Oh! The same as the US, not the UK. Gotchya. Thanks.