How I Fixed My EV6 12V Battery Issues - A Detailed Guide

If you’re facing persistent issues with your EV6’s 12V battery, this post might be the solution you need. After numerous challenges and encounters with unhelpful service center staff, I finally resolved the issue myself and want to share the solution to help anyone else struggling with similar frustrations. Here’s what I learned: The traction battery charges the 12V battery under certain conditions, including while the car is in ‘ready mode,’ during traction battery charging, or through the Auxiliary Battery Maintenance feature if the battery’s charge drops below 80%. Interestingly, many service staff are unaware of the third condition, which can be crucial for understanding and troubleshooting. The ICCU (Integrated Charging Control Unit), similar to an alternator in ICE vehicles, plays a vital role in this process. I discovered that if the 12V battery’s charging protocol via the ICCU is triggered ten times consecutively due to low charge, it will cease to function under the assumption that there’s a persistent issue with the battery. In my scenario, regular short trips and extensive parking periods led to frequent activation of the amber warning light, indicating low battery charge, which eventually led to the battery’s death. The solution involved ensuring the 12V battery was sufficiently charged by keeping the car in ‘ready mode’ for extended periods, which seemed to reset the ICCU’s protocol and resolved the issue. This experience highlights a potential gap in the understanding of EV6’s battery management system at the service centers and underscores the importance of vehicle owner awareness regarding the car’s operational nuances.

Thanks for sharing your solution. I’ve observed that the 12V battery doesn’t charge when the traction battery is below 20%. Last week, I was ill and didn’t drive my car, causing the 12V battery to drop to 60% after starting at 85%. Even while charging the traction battery, the 12V battery did not recharge until I disconnected and reconnected the charger.

@Frey
What tool are you using to monitor your car’s battery levels?

Macon said:
@Frey
What tool are you using to monitor your car’s battery levels?

I use a Home Assistant integration available here: GitHub - Hyundai-Kia-Connect/kia_uvo: A Home Assistant HACS integration that supports Kia Connect(Uvo) and Hyundai Bluelink. The integration supports the EU, Canada and the USA..

@Frey
You mentioned the car doesn’t charge the 12V battery while charging the traction battery under certain conditions. Can you clarify? I thought it should charge regardless during traction battery charging sessions.

@Jules
Correct, the 12V battery should charge during traction battery charging unless the traction battery itself is below 20%. To ensure the 12V battery charges, you may need to restart the charging process once the traction battery is sufficiently charged.

@Mal
It seems counterintuitive not to charge the 12V battery continuously during a charging session. This should be addressed to avoid user inconvenience.

Zion said:
@Mal
It seems counterintuitive not to charge the 12V battery continuously during a charging session. This should be addressed to avoid user inconvenience.

Agreed. The system’s initial check determines the charging protocol, and it doesn’t adjust even if conditions improve, which can lead to these issues.

@Mal
This design flaw could be considered a ‘bug’ in the system. It’s something that could potentially be fixed with a software update to prevent the 12V battery from draining unnecessarily.

@Mal
If that’s the case, it’s a serious oversight. The system should dynamically adjust to changes in the battery’s state of charge.

@Mal
It’s a frustrating design choice that doesn’t seem to serve any practical purpose other than possibly preserving battery life, but it causes more issues than it solves.

Frey said:
@Mal
It’s a frustrating design choice that doesn’t seem to serve any practical purpose other than possibly preserving battery life, but it causes more issues than it solves.

So, as long as the traction battery starts the charging process above 20%, the 12V battery will also charge, correct?

@Jules
Yes, that’s correct. If the initial state of charge of the traction battery is above 20%, the 12V battery should charge along with it.

@Mal
This explains why sometimes my 12V battery charges at different rates or not at all during certain charging sessions. It seems like the system could be more intelligent.

@Frey
In the Hyundai Ioniq 5, a similar model, the charging behavior of the 12V battery was adjusted through software updates. It’s interesting to see that Kia hasn’t applied the same updates.

Is it safe to charge the 12V battery using a traditional charger while it’s still connected to the car?

Skyler said:
Is it safe to charge the 12V battery using a traditional charger while it’s still connected to the car?

I’ve used a trickle charger without issues by disconnecting the terminals. It’s a straightforward process.

@Lex
Does disconnecting the battery reset any vehicle settings or cause other issues?

Skyler said:
@Lex
Does disconnecting the battery reset any vehicle settings or cause other issues?

It mainly affects the climate settings for me. I haven’t noticed other significant resets.

It’s important to note that new 12V batteries often come partially charged and may require an external charge to reach full capacity before installation.