I’ve been seeing a LOT of posts about dead 12v batteries in the EV6. Is this a really common issue, or is it just that people post when it happens and it seems more frequent?
Are certain model years more affected?
And most importantly, what’s the fix? I haven’t come across any solid solutions yet.
There are three different issues going on here.
First is the ICCU failing, which affects a small percentage of early EV6s. This is covered by a recall, so if anyone still has this problem, it’s because they haven’t taken their car in to get it fixed. The fix is available for everyone.
Second, the OEM Kia battery is just not great… They tend to fail. Kia will replace it under warranty, but it’s the same OEM battery, so it might not be much better. A lot of people opt for a good AGM battery instead. I had this issue, and swapping the battery is easy if you’re comfortable doing it yourself. This is more of a Kia issue than an EV6-specific one.
Lastly, this one applies to all EVs: the 12V battery has a higher base load compared to ICE cars. It’s easy to drain it with regular use. Avoid using accessory mode—just start the car fully so the load is taken off the 12V and transferred to the HV battery. If you don’t want the car running but need power, use utility mode. An AGM battery is often a better choice for EVs because it handles the long, steady power draw better than a standard lead-acid battery, which is more suited for short, high bursts (like starting an ICE engine).
@kwame
Great info! One thing I don’t get—if the car is on, why doesn’t the HV battery keep the 12v charged? Seems like it should always be topped up unless you don’t drive for a few days.
Robert said:
@kwame
Great info! One thing I don’t get—if the car is on, why doesn’t the HV battery keep the 12v charged? Seems like it should always be topped up unless you don’t drive for a few days.
Good question. When the car is on, the HV battery does charge the 12V—unless the ICCU is dead. That’s why it’s important to turn the car fully on every time.
If you’re in accessory mode (pressing the power button without your foot on the brake), it’s running the car off the 12V battery only, without connecting to the HV battery.
@kwame
Just to clarify, there’s no “giant spike” when starting an EV. Unlike an ICE vehicle, where the battery needs a lot of power to turn over the engine, an EV doesn’t have a starter motor. The load is much smaller.
@Michael
You’re right, and that’s why I said “the giant spike of starting an ICE vehicle.” EVs have a lower, steady draw when in accessory mode, which is why they can drain the 12V battery if left in that mode for too long.
Edit: typo
@kwame
Ah, gotcha. I must have misread it. Thanks for clearing that up!
The key to keeping your 12V battery healthy is not letting it fully discharge. Lead-acid batteries don’t like being drained all the way—it damages the cells. The eGMP platform (which the EV6 uses) tends to stop charging the 12V when the HV battery drops below 20%, so it’s a good idea to avoid running the HV battery that low too often.
If your 12V fails to start the car even once, it’s probably damaged. I plan to replace mine as soon as I have any issue with it.
I had a long, 6-month fight with Kia over my 2023 EV6, which spent 36 days in the shop with 12V battery issues last winter. In the end, I won arbitration through the BBB and Kia is buying the car back.
Some people never have any problems, but my EV6 killed two AGM batteries. They aren’t always the magic fix people hope for.
@Amelia
I’ve been thinking about going down the same path. I’ve got a 2022 EV6 that I bought used, so it might be trickier for me. But Kia’s on its 5th or 6th attempt to fix it, and I’ve only had the car since January. It’s probably spent 2 months in the shop. I think I have a case, but I need to look into my state’s (Ohio) laws.
My biggest worry is that if I win, I won’t be able to get an equivalent car without spending another $20k. Most of the cars in that price range don’t even have the same features, like rear heated seats, adaptive cruise control, or remote functions via the app.
What are you looking at for a replacement? Another EV?
@Connie
I just leased a 2024 BMW i4 M50 last week to replace the EV6. Kia has until November 24th to take back my car, so I decided to shop while the deals on 2024 models were good.
At least with the Kia Niro, the default 12V battery is notoriously bad, and it seems like the EV6 has the same issue. Once you swap it out, the problem usually goes away. We had a 12V drain issue with our 2022 Niro until the dealership replaced a part of the charging system, and we haven’t had any issues since.
There’s also a recall for certain 12V batteries: https://www.cars.com/research/kia-ev6-2024/recalls/
From what I’ve seen, this issue seems more common with EV6s that are about 2 years old. I haven’t seen many complaints from people who’ve replaced the 12V with an AGM battery. If anyone’s had an AGM replacement fail, I’d love to hear about it.
@Kenneth
Mine died twice last winter after switching to an AGM. It only happened when it was cold out and when I was charging on an AC charger.
Amelia said:
@Kenneth
Mine died twice last winter after switching to an AGM. It only happened when it was cold out and when I was charging on an AC charger.
Do you live in a state where your experience would qualify for a lemon law? I had an ICCU failure last month, but they fixed it quickly, so I don’t think I’d qualify.
@izael
Yes, I do. I just got the decision from the BBB arbitrator this month. Kia is buying back the car. It took about 6 months of back and forth to get it resolved.
Carry a 12V jumper pack. They cost around $50-$100 and you’ll never have to worry about getting stranded.
sorphia said:
Carry a 12V jumper pack. They cost around $50-$100 and you’ll never have to worry about getting stranded.
Sure, you can jump it, but if there’s an underlying issue, you might just end up in limp mode after a few minutes.
@Thomas
That sounds more like an ICCU issue rather than just the 12V battery.
jabali said:
@Thomas
That sounds more like an ICCU issue rather than just the 12V battery.
I replaced my 12V with an AGM and haven’t had any issues for 4 months now. Could’ve been an ICCU problem, but after 2 years and 80,000 km, the OEM 12V battery did alright, all things considered.