2022 I5 SE AWD. Bought new May 2022. 22K miles. No issues with 12V battery until last night. To borrow a line from "The Princess Bride" it was not dead, just mostly dead. Car seemed to start up fine, but then dash displayed "12V battery voltage low. Stop safely". But car would not shift into gear. I had noticed once or twice in the past few weeks I was prompted to touch the fob to the starter button to start the car (but assumed I had to fob in a bag that was blocking the signal). Anyone experience anything similar ?
12V Battery Issue
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US ICCU Recall (aka 12V battery failure issue) and Tesla Supercharger access and adapters. Please do not create duplicate threads on these topics. Links: ICCU Thread | Supercharger Thread | Adapter Thread
Mdmif256
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Very few on this forum or the other one a folow or the FB page a follow compared to the number of cars. Moreover, I would refer to the earlier post “In my assistance through the US dealerships.
About 97% of 12V battery issues are related to aftermarket products being installed incorrectly or blue link app has been merged with other companies like grid suppliers to pull too many syncing.
Less than 3% are related to the 12V battery premature reduction in SOH because of QA or 12V battery mishandling."
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You make that statement as if that's an end to the debate and that we should all just shrug and accept it. It may well be accurate but that doesn't excuse OEMs for also shrugging and walking away.
There must be a way to protect against such operator errors by amending the algorithms that control the health of the 12v battery and avoid 97% of 12v-related driver complaints to dealers. That is time-consuming, expensive in warranty claims, and also forces many drivers to swear to never buy that make again. All avoidable by not ignoring the issue - even if it is operator error - and finding a way to solve the long-standing problem.
For what it’s worth my humble take on the 12v battery issue is this: If the car is used regularly and Bluelink access is limited to less than 4 times per day, then there will be no issue. Also, any third party Bluelink access is severely limited to maybe twice per day. The main traction battery is kept above 34% as below that 12v battery maintenance is severely limited.
There are also caveats to this in that the 12v battery firstly is healthy and has not suffered any low single figure voltages during its lifetime. In my experience standard 12v batteries rarely recover fully if drained to a low voltage. Standard 12v car batteries usually don’t last much more than 3 or 4 years whether used in ice or bev’s.
The BMS and DC to DC converter has been designed and programmed with standard lead acid batteries in mind, other more modern lithium or similar batteries require different charging regimes and voltages. So, although these modern batteries will work, they may not be charging optimally for their chemical and cell construction so lifespan could be limited.
There are owners of bev’s that never suffer any 12 battery issues, maybe because their weekly driving routine and mileage is very similar to what the manufacturers expect and have programmed for.
I had 12v battery problems when my Leaf was 3 years old, and the same 12v battery problems occurred when my Ioniq was around 2 years old. In both cases a new 12v battery solved the issues for me.
There are also caveats to this in that the 12v battery firstly is healthy and has not suffered any low single figure voltages during its lifetime. In my experience standard 12v batteries rarely recover fully if drained to a low voltage. Standard 12v car batteries usually don’t last much more than 3 or 4 years whether used in ice or bev’s.
The BMS and DC to DC converter has been designed and programmed with standard lead acid batteries in mind, other more modern lithium or similar batteries require different charging regimes and voltages. So, although these modern batteries will work, they may not be charging optimally for their chemical and cell construction so lifespan could be limited.
There are owners of bev’s that never suffer any 12 battery issues, maybe because their weekly driving routine and mileage is very similar to what the manufacturers expect and have programmed for.
I had 12v battery problems when my Leaf was 3 years old, and the same 12v battery problems occurred when my Ioniq was around 2 years old. In both cases a new 12v battery solved the issues for me.
That infers that you expect the manufacturer to compensate for whatever the owners does. The car is programmed to stop topping up the 12v battery if it detects what it considers to be unexpected and persistent loading. I would assume this is to prevent possible damage.
Wow! Citations please for your incredible statements here. Blue link is not a third party issue, and not even the only first party issue or primary one. I'd say from what I read on forums, most battery issues in EVs do not arise from third party accessories. That is just an impression, and I have not counted individual issues or threads (but there is an extreme number related to this issue), nor do I have access to manufacturer data (nor does anyone else).
Hyundai Thinks They Know What's Been Killing Your 12V Batteries | Ioniq 5 (youtube.com)
A bit over a year ago there were a lot of issues with dead 12v batteries (and what pushed the notion to have a jump pack available). Hyundi did investigate and attributed it to Bluelink communication overload and due to third party apps using Bluelink. Hyundia did a software change to limit the number of communications and recommendation to change BL password to lock out apps that may have been set up. After this was done, there was a large drop in the number of 12v complaint posts through the majority of 2023.
More recently there has been an uptick with 12v issues again. A number are indicating that it was soon after software updates that many of us have received. TBD if it indeed was due to SW, age or other.
With around 30,000 I5s sold in the US alone in 2023 the number of 12v issues is extremely low!
Moreover, the empirical evidence for the exact cause or causes of these failures seem slacking. We need more exact info.
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Perhaps I over-emphasised the term 'operator error'. Much better to say that such events are only regarded by the OEM as being errors. To the car owner, they don't see a desire to use a third-party program as being an error at all. They see it as a perfectly normal requirement. And if the OEM refuses to enable that to work with their hard and fast regime then conflict will occur.
At the very least they could send a message to the screen to warn of drains that are happening beyond those they have catered for in their own planning. But to just cease topping up the 12v with no warning and allowing the ultimate failure is unforgivable. The manual does say that if the traction battery is at a low charge then the routine top-ups will stop. But how many owners are actually aware of that sentence?
This is an issue that has festered for years. And I find the way OEMs find excuse after excuse rather than grasp the nettle to be quite unhelpful.
100% agree. No question that it is happening to some and the occurrence of posts can give the impression that the sky is falling. Not dissimilar to the ICCU issue. It was real, it was happening to some, not the majority. Part non-availability was real. Fast forward to now, and virtually no ICCU posts.
Yes bugs and problems suck. Maybe Hyundai is not the best, and maybe not so bad. Go to any other new vehicle forum, particularly high tech vehicles, and you will see the exact same thing.
That is not a citation. That is an unsupported claim. And irrelevant to root causes.
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in the case of the ohmmu battery, while there may be a lot of reasons why it wont work, all the posts i have seen is that it has been installed, and nowhere does it say it has failed. as the end user, i dont care WHY it wont work, because it seems like it does, and quite nicely. it just costs more.
It's CCA and it stands for "Cold Cranking Amps". Important when you are trying to crank an ICE, which is not necessary in an EV. An EV needs capacity measured in Amp Hours. The test for CCA is simple; testing for capacity requires that you put a known load on the battery and measure the current over time. So dealers tend to measure CCA right after the battery has been charged, and it looks fine.
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There are many arguments around the theme of it not being the chemistry of the 12v battery that's the issue but the incorrect selection of the type of lead/acid unit. As has been mentioned, the last thing that an EV needs is a huge cranking ability. But such a battery is usually installed. They are also very intolerant to being exposed to a low state of charge for long periods and will fail rapidly.
However, the type of lead/acid battery that is used for leisure purposes such as in boats, caravans and motorhomes will happily endure a deep cycle to low charge rates and work best when charged and discharged across the full 100% available power. There is a good case to be made to replace with such a battery except that they tend to be physically too large to fit.
However, the type of lead/acid battery that is used for leisure purposes such as in boats, caravans and motorhomes will happily endure a deep cycle to low charge rates and work best when charged and discharged across the full 100% available power. There is a good case to be made to replace with such a battery except that they tend to be physically too large to fit.
I'm speaking as a mechanical hardware, & software, engineer of many years experience (now retired), designing machine-control systems since the days of the earliest microprocessors. I created several patents, both in the mechanical engineering arena, as well as IT.
What is meant by "exceeding calibration values" ? The way the Ioniq 5 won't charge the 12V battery in this polled way at all, if the main traction battery is below 20% SOC or whatever that threshold is? Fair enough, but a bit cautious perhaps.
Edit 2 Jan 2024: Post elsewhere here says ICCU update now continues to topup 12V battery down to 10% SOC - a step in the right direction IMHO.
My Ioniq '38 has this inadequate polling system, and originally it polled once per day. Here's a trace of how it attempted (not!) to deal with an unexpected discharge scenario. The cause of this remains unknown, wasn't damp in the door switches, wasn't bluelink.
![Image]()
As you can see, the voltage dropped to well below the stage where a topup was needed.
My battery was damaged by this deep discharge, and another, similar one previously. It was the previous failure that made me design & build my own built-in battery-booster based on 22 Ah motorcycle battery + electronics to ensure my backup cannot be drained by these "vampire" attacks, and install a BM2 Battery Monitor that captured the 2nd such vampire attack shown here. The quick recovery from the attack shown is thanks to this backup working. I flip 2 switches and the 12V battery is changed over.
Finally, late 2022 or early 2023, long after Hyundai has changed to 6 topups/day on the Kona, H decided to apply the same update to the Ioniq! Similar cars & electronics. (Why the Ioniq didn't get this update MUCH earlier baffles me).
So here's a shot of how the 6 topups/day algorithm works with the same damaged-but-reconditioned Delkor OEM battery in it.
![Image]()
A few things have changed with the recent BMS update to 6/day topups. My damaged battery is managing to sit around 12.7V thanks to the regular topups, but immediately after a 5 hour AC charge, where the car holds the 12V battery at 13.0V steadily, the 12V battery drops to 12.5V. So this use of 13.0V during charging is insufficient to maintain a level state of charge in the 12V battery. Fortunately H have added a 12V battery test at the end of an AC charge session, and this test decides that 12.5V is too low, and sets off a series of 5 quick topups each about 20 minutes, and a re-test after.
Having done 4 such tests, the 12V is still only at 12.69V afterwards, but perhaps this is close enough to the pass/fail threshold which seems to be at 12.70V judging by the previous regular topups. At some stage in this re-test process it appears the timer for Regular topups gets reset to zero, as the regular topups restart at about 21:15 on 26 Dec.
Onboard systems aren't going to fix a bad battery, but they should prevent it going bad in the first place. As they clearly have failed to do in my example, and many others in this forum dating back several years.
The correct system design is one where any instance of the 12V battery dropping below a predetermined safety-level (let's say 12.70V as that seems to the the threshold for the regular topups) triggers an interrupt that wakes up a subsystem dedicated to monitoring the 12V battery state. The hardware required for this is minimal, a voltage comparator plus a voltage reference are all that is needed. It's quite possible this setup already exists in the battery-status-monitoring device already connected to the +ve terminals of the battery which reports to the car's computer.
Once such an interrupt is triggered, the code should first determine if it's a momentary spike due to noise or some other transient that can be safely ignored. Things like the spike above at 13:00 in Dec 25 where the wing mirrors operated momentarily. This kind of transient can be filtered out by waiting a few seconds then retesting the voltage to see of the transient passed. This is typically how things like mechanical switch bounces are filtered out, you do a few consecutive retests to see if the condition stabilises, and when it does, only then do you act on it.
Given an interrupt-driven topup mechanism, it would be perfectly possible to start providing topups at a rate of say 3 per hour, or more if neccessary. But you now have the precise timing information of when these topups are needed, and this gives you the ability to take sensible preventative action and log the actual rate for historical analysis.
A pattern of the number of topups per day increasing gradually from say 4/day, to 5/day, to 6/day over a period of weeks/months indicates a battery that's wearing out and needs replacement/reconditioning soon.
A pattern of suddenly needing 2 topups/hour out of the blue, indicates an anomaly of some kind. At this stage you keep applying regular topups, as well as provide other alerts to the owner. Such as a bluelink alert suggesting a door was left open, or something else draining the 12V. If bluelink not in use, a momentary blast on the horn every 5 minutes might be in order. Or flash the headlights. Or something.
A polled system such as Hyundai have implemented cannot cope with the scenario where the power consumed in the 12V devices powered up exceeds the power replaced by the regular topup approach. And the worst scenario happens when something keeps a relatively high-power device active, such as the ?car's computer? consuming maybe 240W, or 20A at 12V. This kind of power draw is enough to drain my 40 Ah battery in a couple of hours, which is less than the interval between regular topups. This kind of sudden high-current drain illustrates perfectly why a polled approach is unable to cope with real-world "extra-ordinary" events. And this is precisely why an interrupt-driven approach is far better.
If H had implemented the correct algorithm, both of my vampire attacks would have been spotted, and I would have been warned, before the voltage dropped to anywhere near 12.0V, let alone the 8.4V I discovered many hours later.
Neither of these damaging, sulphating discharges should have happened.
When there are more and more "clever" things happening, like bluelink, OTA updates someday, remote-fob-sensing circuitry etc placing demands on the 12V system overnight when the car's asleep, it seems rather short-sighted to go downsizing the 12V battery so much! Unless you have a proper charging support system in place, which Hyundai clearly have not.
@HKtech , I'd like to thank you for your participation and help here. I really wish there were more around like you, as it's almost impossible to make any kind of technical connection with large corporations like Hyundai, which tend to hide the technical people behind armies of press departments & management etc. I worked for one such large corporation.
If there's anything you can do to contact the designers of the 12V subsystem, please do, and please pass on my opinions and charts. Thank you again.
This is unacceptably poor design. Everyone is familiar with aftermarket add-ons to car systems, e.g. fancy sound-systems with huge sub-woofers, lighting bars, dashcams etc. Any/all of these may add noticeable extra loads to the 12V battery at any time, and the car should cope with them. I'll explain why it doesn't below, and what the correct design should have been.
You're describing a polled system. This is the simplest way to code up a control system that needs to respond to external events (in this case "low battery"). As any competent software engineer who has worked on microprocessor real-time control systems knows, this method is prone to failiure when the rate of events exceeds the rate of polling. The correct design is to use an interrupt driven system.
What is meant by "exceeding calibration values" ? The way the Ioniq 5 won't charge the 12V battery in this polled way at all, if the main traction battery is below 20% SOC or whatever that threshold is? Fair enough, but a bit cautious perhaps.
Edit 2 Jan 2024: Post elsewhere here says ICCU update now continues to topup 12V battery down to 10% SOC - a step in the right direction IMHO.
My Ioniq '38 has this inadequate polling system, and originally it polled once per day. Here's a trace of how it attempted (not!) to deal with an unexpected discharge scenario. The cause of this remains unknown, wasn't damp in the door switches, wasn't bluelink.
As you can see, the voltage dropped to well below the stage where a topup was needed.
My battery was damaged by this deep discharge, and another, similar one previously. It was the previous failure that made me design & build my own built-in battery-booster based on 22 Ah motorcycle battery + electronics to ensure my backup cannot be drained by these "vampire" attacks, and install a BM2 Battery Monitor that captured the 2nd such vampire attack shown here. The quick recovery from the attack shown is thanks to this backup working. I flip 2 switches and the 12V battery is changed over.
Finally, late 2022 or early 2023, long after Hyundai has changed to 6 topups/day on the Kona, H decided to apply the same update to the Ioniq! Similar cars & electronics. (Why the Ioniq didn't get this update MUCH earlier baffles me).
So here's a shot of how the 6 topups/day algorithm works with the same damaged-but-reconditioned Delkor OEM battery in it.
A few things have changed with the recent BMS update to 6/day topups. My damaged battery is managing to sit around 12.7V thanks to the regular topups, but immediately after a 5 hour AC charge, where the car holds the 12V battery at 13.0V steadily, the 12V battery drops to 12.5V. So this use of 13.0V during charging is insufficient to maintain a level state of charge in the 12V battery. Fortunately H have added a 12V battery test at the end of an AC charge session, and this test decides that 12.5V is too low, and sets off a series of 5 quick topups each about 20 minutes, and a re-test after.
Having done 4 such tests, the 12V is still only at 12.69V afterwards, but perhaps this is close enough to the pass/fail threshold which seems to be at 12.70V judging by the previous regular topups. At some stage in this re-test process it appears the timer for Regular topups gets reset to zero, as the regular topups restart at about 21:15 on 26 Dec.
Incorrect.
Onboard systems aren't going to fix a bad battery, but they should prevent it going bad in the first place. As they clearly have failed to do in my example, and many others in this forum dating back several years.
The correct system design is one where any instance of the 12V battery dropping below a predetermined safety-level (let's say 12.70V as that seems to the the threshold for the regular topups) triggers an interrupt that wakes up a subsystem dedicated to monitoring the 12V battery state. The hardware required for this is minimal, a voltage comparator plus a voltage reference are all that is needed. It's quite possible this setup already exists in the battery-status-monitoring device already connected to the +ve terminals of the battery which reports to the car's computer.
Once such an interrupt is triggered, the code should first determine if it's a momentary spike due to noise or some other transient that can be safely ignored. Things like the spike above at 13:00 in Dec 25 where the wing mirrors operated momentarily. This kind of transient can be filtered out by waiting a few seconds then retesting the voltage to see of the transient passed. This is typically how things like mechanical switch bounces are filtered out, you do a few consecutive retests to see if the condition stabilises, and when it does, only then do you act on it.
Given an interrupt-driven topup mechanism, it would be perfectly possible to start providing topups at a rate of say 3 per hour, or more if neccessary. But you now have the precise timing information of when these topups are needed, and this gives you the ability to take sensible preventative action and log the actual rate for historical analysis.
A pattern of the number of topups per day increasing gradually from say 4/day, to 5/day, to 6/day over a period of weeks/months indicates a battery that's wearing out and needs replacement/reconditioning soon.
A pattern of suddenly needing 2 topups/hour out of the blue, indicates an anomaly of some kind. At this stage you keep applying regular topups, as well as provide other alerts to the owner. Such as a bluelink alert suggesting a door was left open, or something else draining the 12V. If bluelink not in use, a momentary blast on the horn every 5 minutes might be in order. Or flash the headlights. Or something.
A polled system such as Hyundai have implemented cannot cope with the scenario where the power consumed in the 12V devices powered up exceeds the power replaced by the regular topup approach. And the worst scenario happens when something keeps a relatively high-power device active, such as the ?car's computer? consuming maybe 240W, or 20A at 12V. This kind of power draw is enough to drain my 40 Ah battery in a couple of hours, which is less than the interval between regular topups. This kind of sudden high-current drain illustrates perfectly why a polled approach is unable to cope with real-world "extra-ordinary" events. And this is precisely why an interrupt-driven approach is far better.
Agreed. Mine's been down to 8.4V before the drain posted above. Fortunately it's still limping on, thanks to 6 topups/day, and regular use of a de-sulphating + reconditioning cycle on my Ctek smart charger. But I can see my battery is struggling!
If H had implemented the correct algorithm, both of my vampire attacks would have been spotted, and I would have been warned, before the voltage dropped to anywhere near 12.0V, let alone the 8.4V I discovered many hours later.
Neither of these damaging, sulphating discharges should have happened.
People have every right to expect a decent amount of 12V battery capacity. I see that Hyundai decided to fit a remarkably small battery to my Ioniq 38, something more suited to a Toyota Aygo sized car. But there's no high-current starter motor, so, hey-ho, let's fit a tiny one now!
When there are more and more "clever" things happening, like bluelink, OTA updates someday, remote-fob-sensing circuitry etc placing demands on the 12V system overnight when the car's asleep, it seems rather short-sighted to go downsizing the 12V battery so much! Unless you have a proper charging support system in place, which Hyundai clearly have not.
@HKtech , I'd like to thank you for your participation and help here. I really wish there were more around like you, as it's almost impossible to make any kind of technical connection with large corporations like Hyundai, which tend to hide the technical people behind armies of press departments & management etc. I worked for one such large corporation.
If there's anything you can do to contact the designers of the 12V subsystem, please do, and please pass on my opinions and charts. Thank you again.
Third party app should not exceed limit per day for using Bluelink app.
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Yep. March 2022. 30K miles. Dead on vacation in Michigan. Still waiting to hear if the battery I bought will be covered.
Yup. Why do they supply 12v output ports at all if they're going to support them this badly? Sure, set some reasonable limits, e.g., minimum HV SOC to allow 12v top-up, but to totally bail on the problem? Lame.
Seems like it should be easier to deal with this on EV vs. ICE, where the latter has no HV for top-up when the car's off.
Like I said I definitely agree with you on this.
But policy makers and liability are road blocks that are hard to overcome.
Example.
Every time 12V battery calls for recharging it will need both main contactors to cycle through to start ICCU. What is quite expensive on the labor side to replace if they failed.
I will try to bring this on next corporate meeting, for additional software option to enable more active management when owner wants to have aftermarket solutions always powered on.
But there is going to be from engineering standpoint still one problem ( existing 12V battery is quite low Ah rating) and cycling this existing battery will reduce drastically SOH degradation because of not enough energy between recharging.
And from the birth of E-GMP platform it was never taken in to account what some people would love to see ( 200+ Ah battery) ( it is possible to accomplish but it will require a lot of modification and moving 12V battery in the back of the vehicle).
One of the biggest energy users when vehicle is stationary is onboard modem for bluelink, and depending on what bluelink is trying to refresh it may require entire can bus network awake to make necessary updates.
They should reimburse you if you have been in touch with dealership.
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