Follow us today…
Let me set the scene for you. You buy a brand-new Hyundai Ioniq 5. You love the futuristic design, the spaceship dashboard, and the whisper-quiet ride. You’re sitting at just over 3,000 miles—barely out of the honeymoon phase. You park it in your garage, traction battery sitting at 78%, and go away for ten days. You come back expecting to drive off into the sunset. Instead, what greets you is a total system shutdown. The car is completely dead. Not low battery—dead. You have to use a manual key to get in, and then jump-start a brand-new 12V battery just to bring it back to life.
That’s exactly what happened to James Heckathorne, who shared his experience in The Ioniq Guy Facebook group – an increasingly essential place for Ioniq owners to make sense of their EVs beyond the sales brochures and glossy commercials. Here’s what James wrote:
“I parked my Hyundai Ioniq in my garage for 10 days while I traveled; traction battery was at 78%. When I returned home the car was dead as a doornail, and I had to use manual key to enter, and jumped it to start (it’s a new 12V battery installed 45 days ago after the original died within 60 days). The dealer has had it for 2 days, and this text was their note to me. ‘When I spoke to the tech earlier this afternoon about your vehicle he said that due to the vehicle sitting for the amount of time it was without being run, it does tend to kill the 12 volt battery. The 12 volt battery will only charge off the system while the vehicle is running and not draw off of anything in the system while it sits.’ Can anyone definitively tell me if they’re correct? (2024 Ioniq SEL AWD, 3100 miles on the odometer)”
At first glance, that explanation from the dealership almost sounds believable. After all, most of us have had ICE (internal combustion engine) vehicles where leaving it too long without starting could lead to a drained 12V battery. But this is not an ICE car. This is an EV with modern battery management systems—and it’s marketed as being smart enough to maintain itself.
So, what gives?
Why Did the Hyundai Ioniq 5’s 12V Battery Die?
Here’s where things get unexpectedly interesting. Many Ioniq 5 and 6 owners, especially those who hang around online forums and Facebook groups, have already encountered this head-scratcher. A dead 12V battery in a nearly brand-new EV? That’s not just inconvenient—it’s deeply unsettling.
But James is not alone.
Matthew Hunt, another group member, responded with hard evidence that throws the dealership’s diagnosis into serious question. He wrote:
“That’s certainly not true. There’s the amber light on the dashboard that comes on when the car is charging the 12V while parked. If they need proof, the description of service campaign 9A1 states: ’12V battery saver logic update allows charging from EV Battery as low as 10% SOC when parked.’”
He even included a link to the actual campaign PDF from the NHTSA. This isn’t speculation or hearsay—it’s documented policy from Hyundai itself. And it suggests the dealership may not be fully up to speed on how the Ioniq 5’s battery systems are supposed to work.
Marq Anderson summed it up with a blunt:
“Find a new dealer.”
Honestly, it’s hard to argue with that sentiment.
What’s Really Going On Under the Hood?
Let’s take a second to talk about the 12V system in EVs like the Ioniq 5. Unlike traditional vehicles where the alternator charges the 12V battery, EVs use something called a DC-to-DC converter to transfer power from the high-voltage traction battery to the low-voltage 12V battery. In well-designed systems, this charging happens periodically, even when the car is off—as long as it has enough charge.
Don Oltman weighed in with clarity:
“The 12V charges periodically from the traction battery using the DC to DC converter in the ICCU. Lights the amber light on dash while it’s happening.”
That amber light is more than a pretty glow. It’s your sign that the system is doing its job.
And yet, stories like James’ keep popping up. Could there be something else at play?
Could Hyundai’s Software Be “Pinging” Your Car Awake?
Now here’s where it gets unsettling again. Some owners suggest that Hyundai’s BlueLink system – the connected services platform that lets you check on your car from your phone – might be keeping the vehicle awake too long or too often.
It’s a theory that’s been echoed in discussions around other Ioniq 5 charging quirks, such as this experience shared by another Ioniq 5 owner, where the user was surprised by how BlueLink was behaving during a service issue. There’s also this report about a 2020 Ioniq EV that required frequent boosting of its 12V battery, even though everything appeared fine on the surface.
Some savvy users have even suggested resetting the BlueLink system entirely. One solution? Change your account password to break the connection, or delete and re-add your car in the app. It’s not elegant, but it could stop the phantom energy drain.
So… Is the Dealer Right or Wrong?
The answer is not black-and-white.
Eric Russel brought a balanced perspective to the discussion:
“What he said is basically true for an ICE car, although 10 days shouldn’t kill a battery in an ICE car if the battery was in good shape. But modern EVs are designed to top off the 12V battery occasionally using the traction battery even when the car is not turned on.”
In other words, the dealership’s logic is stuck in 2005. The 2024 Ioniq 5 is built to avoid this issue—at least on paper. If your 12V dies after ten days of sitting, it’s a symptom of something else. Maybe a firmware update is missing. Maybe BlueLink is overactive. Maybe there’s a hidden parasitic draw.
Why the Ioniq 5 12V Battery Failing Matters More Than You Think
This isn’t just a “nuisance” problem. It’s a real ownership concern. EVs are supposed to be low-maintenance. That’s one of their biggest selling points. But if you have to worry every time you leave your car parked for more than a week, that’s a major trust issue.
If you’re thinking long-term about EV ownership, you’ll want to read how long the Ioniq 5 battery lasts and whether you should charge it every night. These discussions aren’t just about longevity—they’re about living with these vehicles in the real world.
Is There a Fix or Workaround?
One useful habit is to manually put your Ioniq 5 into Utility Mode for a few minutes once a week. This helps trigger a recharge of the 12V battery. You could also consider using a smart trickle charger—something that connects to the 12V and automatically tops it off when needed, though that does add extra steps for a vehicle that’s supposed to be plug-and-forget.
Other users like Mike Cebual reported no issues after 30 days of inactivity:
“Mine’s been home sitting for 30 days. Hyundai online system lists it as 2% loss (left at 70% SOC, now 68%). I’ll be home tomorrow.”
That’s how it should be working for everyone. So when it doesn’t, you know there’s a bug in the system—either software or hardware.
A Design Flaw That Needs Addressing
Thomas Smailus nails the big-picture concern:
“That may be true. The big question is for Hyundai: why did they design the car to not also draw zero power after the car has sat for over 24 hrs unused? Just have it hibernate. There is zero point in having all that electronics still running other than some super low power zigbee radio-like device that wakes up the car when someone bumps it to open it.”
Why shouldn’t an EV be able to fully hibernate, especially when it’s parked at home and not needed?
In a market that includes cars like the Tesla Model Y—where vampire drain is also an issue but more widely acknowledged—Hyundai needs to decide whether it wants to own the problem or keep letting dealerships push outdated ICE logic.
What Can Hyundai Owners Do Right Now?
Until Hyundai issues a more robust fix or clearer guidance, Ioniq 5 owners are left navigating a maze of patchwork solutions. Your best bet? Keep firmware updated, manually wake your car now and then, disable BlueLink temporarily if you suspect it’s an issue, and – most importantly – push your dealership to escalate unresolved problems.
Also, if you’re noticing weird behavior when charging your Ioniq 6 or 5, like strange dialog boxes or screen errors, you might want to read about this annoying software bug owners have reported. These small symptoms may be connected in ways we’re only beginning to understand.
So what do you think, should EVs like the Ioniq 5 be allowed to fail like this just because they’ve been sitting idle for a few days? Or is this a problem of dealers not catching up to the EV era?
And if you’ve left your Ioniq parked for an extended time, how long did it last without issue? Would love to hear your experience.
Armen Hareyan is the founder and Editor-in-Chief of Torque News. He founded TorqueNews.com in 2010, which since then has been publishing expert news and analysis about the automotive industry. He can be reached at Torque News Twitter, Facebook, Linkedin, and Youtube. He has more than a decade of expertise in the automotive industry with a special interest in Tesla and electric vehicles.
Follow us today…
Source: torquenews.com
