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12-volt batteries are still ubiquitous in modern battery-electric vehicles. As you know, the 12-volt battery is the classic one under the “hood.” It powers accessories like lighting, power locks, power seats, your infotainment system, and much more. Despite electric vehicles now having massive high-voltage traction batteries, which we will call the “EV battery,” 12-volt batteries are still in nearly every vehicle sold today. Unfortunately for EV owners, the 12V batteries often fail prematurely, and the car won’t work without one operating properly.
Hyundai Ioniq 5 Battery Failure Reports
One model that is struggling with a lot of posts about premature 12V battery failures is the Hyundai Ioniq 5. Our favorite EV overall, this is a very popular model. Here are some posts we found inside Ioniq 5 groups on social media, starting with the one that we used in our headline as an example:
-G.P. – “After 2 years, my Ioniq 5 had faced the issue of a dead 12V battery, and they changed the ICCU. I asked them to change the 12V battery, but they denied (the request). This was just two months ago. Since then, the battery keeps dying. It died seven times in the last 10 days alone. I had to purchase a jump starter to avoid waiting time for a tow truck.”
-C.N. – “I had my 12v replaced under warranty this week. The car isn’t even 1 year old. 14000 km.”
-H.I. – “I’m on my third dealer. The first shooed me away because they had no EV-certified techs. The second had not the slightest clue of what caused my dead 12V battery. The third did a careful diagnosis and replaced the battery under warranty.”
You may notice that some of these Ioniq 5 owners are referring to the ICCU (Integrated Charging Control Unit). This is a part of the vehicle that is tasked with charging the vehicle’s EV battery, and it has other roles as well. Owners are discovering that there seems to be a correlation between ICCU issues and 12V battery failures.
Tesla Moves to 16-Volt Batteries After Many Frustrated Customers
Tesla began migrating away from 12-volt batteries back in 2021, but the brand was still reportedly building vehicles with 12-volt batteries as recently as 2023. For example, this past June, a 2023 Model Y owner of initials J.K. reported that his Tesla Model Y’s low-voltage battery had quit and left him stranded. He discovered his Model Y was equipped with a 12-volt battery, and it failed in less than two years. Perhaps Tesla’s switch to the 16-volt architecture will prove more reliable for the brand?
EV Jeep Battery Failure Leaves Owner Stranded In Parking Garage
Either a jump start or a tow is the solution to a 12-volt battery failure, right? Well, not if you are in a Massport-controlled parking garage at Boston’s Logan Airport. Here’s what one EV owner dealt with after her Jeep EV’s low-voltage battery died:
Last night was an adventure. My 12V died (again) in my EV. This time in the garage at Logan. Only MassPort will tow out of the garage, and then transfer to your tow of choice outside. As an EV, you have to flatbed it, so it’s dollies to get it out of the garage. This is where our story literally goes sideways. The tow damaged the car, leaving me with more repairs to deal with. Three batteries so far, I’m looking at a buyback. 3K total miles on this EV.
This owner’s Jeep model is not even two years old, and she has had three 12V batteries!
Subaru and Toyota EV Battery Issues
Toyota and Subaru co-produce their battery-electric models. Owners report battery failures. Here’s one example:
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I am experiencing repeated failure of the 12V battery in my 2025 Solterra. A fully charged battery that reads 12.1 volts often drops to 3.0-3.4 volts in 48 hours. This low voltage makes the vehicle unable to start and requires jumping or charging with a battery charger. The vehicle has been at our local dealer, and they are unable to solve the problem. They have discovered that something is causing “intermittent spiked 1.5-amp drawdowns” on the battery. All apps including the newest version of Solterra Connect have been removed from my phone. Is anyone else experiencing this issue?
Frustrated EV owners have filed in the U.S. Eastern District Court of California to try to find a resolution to this ongoing 12-volt battery failure issue.
Don’t Blame the Alternator
In many vehicles with traditional powertrains, the 12-volt battery dies for a reason. Often, it is related to a failing alternator, the electromechanical device that recharges your battery as you drive, and the accessory belt spins the device. Many hybrid and all EV powertrains don’t use alternators. Instead, they have what are called DC to DC converters. These are solid-state devices that use the power in the high-voltage EV battery to charge up and maintain charge in the low-voltage 12V battery. EVs don’t use alternators, but they still suffer 12V charging issues.
Not Every EV Kills Its 12-Volt Battery – The Chevy Bolt Example
There is no reason why a 12-volt battery must die a quick death. Case in point, Chevrolet Bolt owner V.A., who reported this month:
I was cleaning the compartment under the hood of our newly acquired 2018 Premier with 57k miles. I took the battery out to blow out all the dust and debris, and found out the 12V battery is original to the car. The battery was manufactured in December 2017. The battery is almost 8 years old, and I’m surprised it lasted this long.
In July, another Bolt owner of the same group had her Bolt die, only to discover the 12V battery was eight years old. Fellow Bolt owner I.S. reported, “Replaced my 12V at nine years, 170,000 kms.”
Is the 12V Battery In My EV Covered Under Warranty?
Unlike the rest of your vehicle, 12V batteries are often covered for some portion of the new car warranty. No brand offers a warranty on the 12V battery for the full powertrain warranty, even though the powertrain cannot function without it.
Electric vehicles are complicated machines with many problematic moving parts, and even non-moving parts with problems. The 12V battery is one example of a common trouble spot that many modern EV owners deal with. If you have had trouble with your EV’s 12V battery, or, by contrast, your battery has lasted a surprisingly long time, please add to the discussion by adding a comment below.
John Goreham is the Vice President of the New England Motor Press Association and an expert vehicle tester. John completed an engineering program with a focus on electric vehicles, followed by two decades of work in high-tech, biopharma, and the automotive supply chain before becoming a news contributor. He is a member of the Society of Automotive Engineers (SAE int). In addition to his eleven years of work at Torque News, John has published thousands of articles and reviews at American news outlets. He is known for offering unfiltered opinions on vehicle topics. You can connect with John on LinkedIn and follow his work on his personal X channel or on our X channel. Please note that stories carrying John’s by-line are never AI-generated, but he does employ grammar and punctuation software when proofreading and he also uses image generation tools.
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Source: torquenews.com
