12V battery in 2016 Kia Soul EV keeps dying

[Martysmom]

Hi,

I’m writing about a problem I’ve been having with the 12V battery in my 2016 Kia Soul EV. My car has about ~39.5K miles on it and, although the range on a full charge has been steadily dropping (from 112 miles down to 89 miles), it was working fine until this past May. My car wouldn’t start and had it towed to the local Kia dealer who determined the (original) 12V battery was dead so they installed a new one. I don’t drive the car every day but, since then, there have been at least 4 other times where the car won’t start because the battery is dead. This last time, I parked the car on a Thursday and the following Wednesday it was dead, not having been driven in-between.

The technicians are telling me that because the computer in the car is always ‘talking’ to the system, it uses up the 12V battery and I need to drive the car more often to keep the battery charged. On one hand, I get it, but on the other hand, I don’t think I should have to drive the car for no reason when it hasn’t been sitting that long.

I asked the dealership about the software update bulletin from a couple of years ago (can’t find right now), but they said that was closed out in 2021. Has anyone else run into this and did you have a solution? Are the technicians just blowing smoke? All they ever seem to tell me is everything is withn standard/normal operating parameters.

Thanks in advance for your help,

Daria

 

[ksoul2084]

The battery shouldn't die just because the car is sitting parked for under a week.

However, I have read that if you leave the car plugged in, but not charging, for an extended period (days?) that can cause the 12v battery to drain.

The other possibility is that your "new" 12v battery was permanently damaged by the 4 times it was completely drained and needs to be replaced again.

 

[IanL]

Mine will slowly lose charge if left standing. There are two good options;

Periodically, put a trickle charger onto the battery to bring it up to full charge. If you use a modern, electronically controlled charger, there is no need to disconnect the battery from the car.

If the car is in daylight, plug a solar panel charger into the OBD connector whenever the car is out of use for an appreciable time. It won't recharge a low battery, but it will maintain the level. If the car is kept in a garage, you can periodically switch on the traction system in P mode, and it will recharge the 12V from the traction battery - the downside is needing to remember to switch off after a few hours.

I have fitted a BM6 monitor to my battery, so I can keep an eye on it with my phone. Using the car 2 or 3 times a week for a five mile run, I don't need to charge - less, and I charge it maybe every 2 weeks.

More modern EVs use the traction battery and dc-dc converter to charge the 12V battery when the car is switched off. My Fiat 500e seems to do so when the SOH drops to 60%.

 

[Martysmom]

Thanks very much. I'll check these options out!
Daria

 

[alexank]

The little battery doesn't have a particularly high capacity many are replaced unnecessarily imho as they could be masking a potential different fault.
The cars don't usually have much of a parasitic load but this can increase significantly especially if an ECU crashes or hangs without shutting down and going into sleep mode.

Changing the battery effectively resets and reboots everything so masking the problem till it happens again
The later 2020 onwards 2nd generation cars have a battery saver option which helps but is not perfect.

I got into the habit of fully charging the battery in my 2016 car every couple of weeks if not being used.

I recently had an ecu crash in my 2020 car which I posted this about a couple of weeks ago on FB:

"
A different spin on a flat 12v battery.
Yesterday around 16:00 my BM2 app warned the 12v battery in our FE was down to 12v. It usually sits at around 12.8-13v permanently.
This is the first time in this car it’s played up.
I was about to swap it out with the virtually as new superior Yuasu battery I had taken out of our 2016 car before we sold it.
However I noticed from the app data the voltage was dropping rapidly suggesting a load.
The graphs from last night and this morning show how fast it was discharging after the charger stopped at around 22:00.
It was down to 10.5v by the time we went shopping this morning
I have just been out with my current clamp. Disabled the bonnet switch and locked the car, after a few minutes the current should drop to near zero. There was actually a constant 3-5A load on the battery something in the car had crashed and hung.
I disconnected the battery for half an hour and then monitored the current, it was behaving properly.

Earlier this week there were some odd symptoms rear doors didn’t unlock, key fob response erratic almost as if the key’s battery was flat. This morning I am almost certain the DRL didn’t come on….
It will be interesting to see what happens over the next few days the problem has coincided with the recent freezing weather and us using the remote climate command.
I had noticed the steering wheel heater had come on even though that option was turned off in the app.
If it wasn’t for the fact I know it’s voltages have been ok I would think the 12v battery was probably the cause of all this and on its way out but the symptoms initially suggest something else"

 

[IanL]

Very good to know. Btw, what is FB?

 

[shumanchu]

In my 2016 Soul Ev, the 12V battery would die all the time. I kept a booster pack with me to deal with it. I have since replaced the battery and the issue has gone away, for now.

What I have been able to deduce from monitoring things via OBD2 and torque pro:

The LDO regulator that is responsible for charging the 12V battery will only turn on and charge the 12V under certain conditions. If you do not meet those conditions during your normal driving, then the 12V battery has to run all the 12V systems in the vehicle without being charged. Eventually this causes the battery to drain past a safe level and permanently damages the 12V battery.

The conditions that will cause the LDO to turn on and charge the battery are:

1) When the battery monitoring device located on the negative battery terminal wiring harness tells the vehicle to enable the LDO because the battery needs charging.

2) if the headlights are on. Note: not the DRL, but the main halogen headlights. In fact if the DRL are on only, the LDO will remain off and the DRLs are powered by the 12V battery, further causing drain on it.

Now the issue lies with condition 1. For some reason the battery monitoring device that should be taking care of charging the 12V battery when it needs charged is not working right, or perhaps they set triggers that were too conservative or too simplistic. Who knows?

The remedy that I have been using is to use option 2 to force the charging of the battery. Even in daylight I'm out here with my low beams on.

And if your existing 12V battery has a resting voltage at or below 10.5v, then it is probably damaged and needs replaced.

Of course if youre going to leave the car sitting for a long period of time, like many weeks, then I would throw a trickle charger on there because there probably are lots of modules that wake up and run periodically which constitue a parasitic load on the battery.

 

[IanL]

There would seem to be something wrong with the system in your car. My 2018 SoulEV charges the auxiliary battery at 14.47 V with the headlamps off (just the DRLs on). I can see this on my BM6 Battery Monitor. The voltage goes from about 12.75V to 14.47V the moment I press the power button with the brake pedal depressed. The headlamps are off (confirmed by sight).

When I performed this test, the SOC of the auxiliary battery was 82%.

 

[DOLSENATOR]

My 2017 Kia Soul EV has a bad head unit (main screen/radio) it does not go to sleep properly plus some other issues and will drain the battery in about 8 hours. I am hoping to have it replaced after the holidays. In the mean time, we pull the fuse for it if not using the car for some time or not charging. This can be a problem in newer vehicles due to the lead free solder used. The solder will grow tiny metal hairs that can cause shorts, etc. due to stresses (temperature changes, vibration). Or it can be an electronic component failure (transistor, IC, etc.). This can happen to any of the electronic modules in an older modern vehicle.

To find the issue, I had to play musical fuses till I found the culprit causing the battery drain. I too changed the battery after the first couple times it died. but when it died with the new battery I had to go looking for the cause. The issue was intermittent at first, but now is always there.

 

[shumanchu]

There would seem to be something wrong with the system in your car. My 2018 SoulEV charges the auxiliary battery at 14.47 V with the headlamps off (just the DRLs on). I can see this on my BM6 Battery Monitor. The voltage goes from about 12.75V to 14.47V the moment I press the power button with the brake pedal depressed. The headlamps are off (confirmed by sight).

When I performed this test, the SOC of the auxiliary battery was 82%.

Have you monitored the voltage for the entire duration of a hour long drive? I have seen the LDO kick out 14v at startup for a little while then it decides at some point to turn off. Usually after 10 minutes or so. Of course it is highly likely that your 18 MY has different parts or firmware relating to this issue. The 16 MY was kind of the guinea pig for the platform.

 

[JejuSoul]

There's a previous thread about turning off the 12V system - Going on Vacation - Turn Off 12V Battery with Fusebox Switch.

 

[FLKiaEV]

I always thought it would be useful for there to be a "long term storage" option in the settings so that you could plug in your vehicle and then it would monitor the whole system and charge when needed (including the 12V battery). When I got my 2016 Soul Ev the first thing I did was replace the OEM battery with a lithium ion one. I don't regret that decision because I've not had a single issue with it. I do check the voltage about once a month to make sure everything is okay and always reports 13.3V or thereabouts.

 

[IanL]

Have you monitored the voltage for the entire duration of a hour long drive? I have seen the LDO kick out 14v at startup for a little while then it decides at some point to turn off. Usually after 10 minutes or so. Of course it is highly likely that your 18 MY has different parts or firmware relating to this issue. The 16 MY was kind of the guinea pig for the platform.

Small island, so hour long drives are very rare, but I would expect the charging voltage to drop at some point when the battery ceases to take current, i.e. charging is complete. The system ( Btw what does LDO stand for?) would then reduce output volts probably to something in the 12.7 to 13.3 range, to supply the 12V services, and the battery would just float on that, with minimal current through it. This is what modern car alternators do.

But the main point of my post was that the LDO should charge the battery whenever the car is in the RUN state (i.e DRLs on) irrespective of headlamps, so if yours does not, something is amiss. Perhaps someone else with a 15 or 16 MY could says what their's does?

 

[ksoul2084]

Have you monitored the voltage for the entire duration of a hour long drive? I have seen the LDO kick out 14v at startup for a little while then it decides at some point to turn off. Usually after 10 minutes or so. Of course it is highly likely that your 18 MY has different parts or firmware relating to this issue. The 16 MY was kind of the guinea pig for the platform.

Perhaps it cuts out when it considers the 12v battery "charged"? Turning on the headlights adds some significant load to the 12v circuit, causes the voltage to drop, and triggers the charger to re-engage?

 

[FLKiaEV]

For about $30US you can connect one of these bluetooth 12V battery monitors that sends real-time info to your phone about your 12V battery: https://a.co/d/3jflBLv