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Have read a few threads in this forum on the 12volt battery. This is a real issue.

We had had this issue a few times, with the doors open for not very long - maybe 15 minutes. At the 2 year service we asked for the battery to be checked and were told it was fine.

Now stranded again, after doors open for five minutes to load the car. Ridiculous. And it is a Saturday, so Hyundai service is closed.

seriously frustrated that the battery was not changed at the 2 year service!!!!!
Wondering whether to find a different type of 12 volt battery!
 

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This is not normal. Either the battery or charging system is not working as it should. You should not need an upgraded battery. If under warranty, take it to a different dealer. If out of warranty you could try AutoZone ( or any other similar reseller) and have then test the battery by applying a load to the battery.
 

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There is nothing different here than any other Kona EV. You can get away with 20 minutes if your 12V battery is in top condition. Using a different 12V battery is not going to help.

For whatever reason the car wakes up to a level where it expects you to get in and drive. A similar thing can happen if you plug in your home charger when it is not powered-up. The car keeps trying and may drain the battery in desperation.

If you want to leave the doors open simply place the car from Run to Utility mode using the dash menus and you can leave them open all day. It cannot be driven in or from that mode without having the key present and starting from "off".
 

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Interesting that the main battery doesn't kick in, like on Teslas. If I left doors open (like when cleaning it, or something), the main battery was active until in about 15 minutes, it killed everything (sleep mode). But they had issues not charging the 12V batteries correctly, and having to replace them every 2 years too. So it's always something. Ha ha. But glad to read about the 'utility' trick, since we plan to buy a Hyundai EV after the Kona N. We weren't a fan of the Tesla, but fortunately we tried it for 1-1/2 years for free, since we actually made $3,500 (after all taxes, accessories, and even a 240V outlet installation. Ha ha) when we sold it 2 weeks ago. But it's still too early for EVs now IMO, especially where we live, so will wait a few years for charging infrastructure to catch up, and reliability to be better.
 

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I’ve had this flat battery issue 6 times now. Very frustrating. Withiut knowing this forum, it took me 3rd time to think that it was probably due to the boot door open for loading and or doors so always took care. Now I learn it is more than that and a fundamental issue. Why don’t Hyundai admit it and warn customers?

The last time was last weeken having driven to Edinburgh for the weekend , we unloaded and before locking I checked the battery ( I always carry a charger and cable now which yo7 have to have reachable from the driver seat because as you all know, yo7 on,y ge5 access there wit( the emergency key) and it was 100%. Then we went out for the afternoon and dinner , and 6 hours later, I could not open the car! Battery flat! Nextmorning , a Saturday, I callen Hyundai Road assistance who arranged a friendly AA van. He boosted the battery and the car started. (The main battery will fully charge the 12v battery if you leave the car on in Neutral) . He also did a battery health test which took 10 minutes , and said “Replace Battery”. He even arranged for the Edinburgh Hyundai’s garage to squeeze me in to do it. Got there (20 mins drive) and they had it for 10 minutes and said a battery is fine, must be an issue elsewhere with the electronics and I had to make an appointment with my home garage ( Aberdeen). They had looked at it in March and could not find anything wrong with the battery or the electronics..SO THEY DONT SEEM TO KNOW ABOUT THE ISSUE WHICH BY THIS AND OTHER THREADS IS COMMON! They should ah e at least said , don’t leave the doors or boot open more than a few minutes!

what else causes this. What a design fault!

I’ve baught a battery booster to keep with me now instead of the battery charger. Its unclear to me if it is suitable for the Kone battery as the booster is rated for 1500cc cars or smaller. ( how is that relevant) https://www.amazon.co.uk/dp/B00FB7LTO8?psc=1&smid=A3P5ROKL5A1OLE&ref_=chk_typ_imgToDp

Watch this space. I have an appointment on 16th August and demanded a courtesy car so they can keep the car for a week to test it properly.
 

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... Now I learn it is more than that and a fundamental issue.
...what else causes this. What a design fault!
If it's a fundamental issue I don't have it, but I don't have BlueLink telematics either which makes me wonder if that's a factor. Next month my Kona and 12V battery will be four years old. If you buy and install a BM2 Battery Monitor you can not only keep an eye on it on a daily basis but also have good evidence for a diagnosis.

Leaving the boot ajar is just as bad as leaving it open and in both cases the car refuses to charge the 12V battery for the interim. Be sure you've twisted in the two adjustable rubber boot stops to reduce the risk.
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Hi,

I’ve had my Kona EV 64KW now for just over two years. I’ve suddenly got the same issues with the 12V battery. It’s not only an issue with leaving doors open etc, the batteries are failing after about two years.

I’ve had a check done on my battery by an AA guy and the readout said failed battery, replace. There’s either something wrong with the batteries that Hyundai are being supplied with or there’s an issue with the charging. For example it may be that the charge volts are slightly too high (the charge volts are higher than on a regular ICE car) and this may in time be causing the acid solution to vent off too much.

The batteries used are not exactly the same as regular ICE car batteries and in fact are somewhat less capable. They don’t have to crank over an engine and supply 100A for a few seconds after all.

I’m taking my car to a Hyundai dealership now and see what they come up with.
 

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Give up the battery on the Kona are lousy and Hyundai is not accepting blame for them. Tesla has found a sort of a fix by replacing them with a deep cycle battery which will allow for more discharge and recharging cycles also in my view especially in colder zone the placing of the tiny 12 volt battery in a warmer site on the car may help as well, cold is not a friend of batteries. in addition Costco has a battery which could be used as a replacement battery, it is an R class battery which means that the location of the terminals are swapped as required by the kona all the other mesurament are the same except for the height but there is a workaround to that and will require for the grounding cable to be loosened (not removed) in order for the grounding clamp to be placed over the terminal. the benefit is that the battery is half the price and double the years of warranty, 4 years. Caviat what that will do to the Hyunday warranty I do not know better check before using that work around fix
 

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2022 Kona 64kWh Ultimate delivery end of 2022.
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The Kona electric has two 12 volt outlet sockets. You are allowed up to 180 Watts = 15 Amps. I suppose these are connected to the 12 volt battery, but maybe not directly. Anyone seen a circuit diagram? Probably not! If the sockets are connected directly to the 12 volt battery, it would be possible to connect a small portable 12 volt battery through one of these sockets - just long enough to start the car. These sockets are likely fused so I suppose this fuse could be blown by the charging current, if it exceeds about 20 amps, which current will flow as soon as the external battery is connected. Hyundai does warn that devices with internal batteries should be connected with a reverse current block to avoid possible damage of the car's electronics should current be forced backwards. I have the feeling that so long as the voltage does not exceed around 14 volts - no harm should result - but what do I know? If this was allowed, I would certainly pack a small 12 volt lead acid battery in a foot well for long journeys! Otherwise a light jump-lead connection could be made direct to this horrid little Kona battery. I do not want to be stranded in foreign climes by this silly fault!
 

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My12 V battery went dead could not open the door, had to use the key in the fob to gain the entree and open the hood finally was able to start the car by jumpstart it from my wife’s car drove to dealer to be told I had a dead battery and needed replacing $ 300 Hyundai only guaranties it for 2 years. Had it replaced by a Kia dealer for cheaper and a higher amperage why does Hyundai not do what Tesla did and use a deep cycle battery it would last longer and cost less I guess it would lower their profit
 

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FWIW: My wife has driven a 2021 Kona EV (the middle grade one, no leather seats) since Aug 2020.

I told her back on day one of ownership, that (unlike my TM3) the Kona will run only on its 12 volt battery when one enters the car and “farts around” with this that and the other thing UNTIL the car is turned on and one gets the green symbol that shows its ready to drive.

Since day one, she has been very good at ensuring the very first thing she does after entering the car is to actually start it (engage the traction battery for all 12 volt services) and then “fart around” with adjusting this, that and the other thing.

I’m the designated car detailer/basic mechanical service person; anytime I work with this car, I always start it first and then proceed to do what needs doing.

The above techniques minimize the time the 12 volt battery has to carry the load on its own; hopefully that translates to a 48 month or greater service life for the 12 volt battery.
YMMV
 

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FWIW: My wife has driven a 2021 Kona EV (the middle grade one, no leather seats) since Aug 2020.

I told her back on day one of ownership, that (unlike my TM3) the Kona will run only on its 12 volt battery when one enters the car and “farts around” with this that and the other thing UNTIL the car is turned on and one gets the green symbol that shows its ready to drive.

Since day one, she has been very good at ensuring the very first thing she does after entering the car is to actually start it (engage the traction battery for all 12 volt services) and then “fart around” with adjusting this, that and the other thing.

I’m the designated car detailer/basic mechanical service person; anytime I work with this car, I always start it first and then proceed to do what needs doing.

The above techniques minimize the time the 12 volt battery has to carry the load on its own; hopefully that translates to a 48 month or greater service life for the 12 volt battery.
YMMV
Does the car stay turned on when you open the doors - presumably in Park and brake-on it will? What is the difference between that and "Utility" mode?
 

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Does the car stay turned on when you open the doors - presumably in Park and brake-on it will? What is the difference between that and "Utility" mode?
Yes, the car stays turned on.

I keep the key fob in the car (on top of the dash for visibility) so that I don’t have to endure the warning tone telling me I have left the car running and no one (with a key fob) is sitting in the drivers seat.

I never use Utility mode so I have no idea what difference there may be.
 

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Yes, the car stays turned on.

I keep the key fob in the car (on top of the dash for visibility) so that I don’t have to endure the warning tone telling me I have left the car running and no one (with a key fob) is sitting in the drivers seat.

I never use Utility mode so I have no idea what difference there may be.
Thank you.
 

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... What is the difference between that and "Utility" mode?
In Utility Mode the 12V battery is subject to a moderate charging voltage for the duration, yet the car cannot be driven away without restarting with the key present. In Run Mode the charging level is the maximum for a limited time and of course the car is ready to go.
The Kona electric has two 12 volt outlet sockets. ..., it would be possible to connect a small portable 12 volt battery through one of these sockets - just long enough to start the car.
That is not possible, you need to access the 12V battery directly.
 

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I have read in forums that the Hyundai 12 volt battery is considered by many to have poor performance and many recommend changing it, against Hyundai advice, for another high-end, expensive, glass-mat type. I wondered if changing the battery type might upset Hyundai's State-of-Charge assessment because different batteries may have different curves. I was interested to find out how feasible it is to judge the state of charge with voltage measurements. I found this on the Net. (Battery University - BU-903)
"To get accurate readings, the battery needs to rest in the open circuit state for at least four hours; battery manufacturers recommend 24 hours for lead acid. This makes the voltage-based SoC method impractical for a battery in active duty.

Each battery chemistry delivers its own unique discharge signature. While voltage-based SoC works reasonably well for a lead acid battery that has rested, the flat discharge curve of nickel- and lithium- based batteries renders the voltage method impracticable."

There are two things of interest in that statement.
Firstly the Kona's 12 volt battery is virtually never in an open-circuit state for significant time. Perhaps that is why it is practically impssible to give warnings of an impending 12 volt failure. Does Hyundai attempt to record in and out flows for the 12 volt battery? (We know 12 Volt battery current is monitored.)

Secondly it is even worse for the power-train battery. That means that Hyundai must attempt to keep track of the SoC by recording in and out current flows. So how good and reliable are range-left indications?

Still waiting for my Kona EV delivery - it has only been 9 months.
 

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I think it's not practical to entirely rely on coulomb counting on a lead-acid because of natural discharge. The lithium-ion traction battery is another story and holds a charge very well over a long term. Those counters are readable and very useful, at least to me. Plus it can do OCV readings while the traction battery is unloaded.

The Kona's 12V battery sensor can log anything it wants 24/7 but no one knows what parameters Hyundai download when the car wakes up usually ever 4 hours. When the car is parked that's a good enough no-load condition after 4 hours to evaluate SoC based on voltage. I occasionally see the car adding an intermediate charge (at 2 hours) when it thinks the battery is low but it's often hours later, well past catching a problem that might cause a failure to start.

12V battery complaints roll in almost every day from owners globally and the blame is often placed on the battery quality, despite no evidence. I would suggest that it's more down to:
1. A door left ajar.
2. Excess BlueLink comms, in several cases because the owner shared the login details with a third party. One owner used an Android emulator and that excessively-polled the car.
3. The battery being already weakened from a previous deep discharge and pushed over the edge again. Many seem to assume that it can be fully recovered by charging it.
4. A "smart" wall charger that repeatedly attempting to initiate a charge session when that is prevented for other reasons.

There's no question that the smallish OEM DIN44 12V battery has only barely enough capacity to handle normal start and shutdown tasks, and the systems cannot detect excessive drains when the car is "off". But, most owners don't have any issues. My 12V battery below is 51 months old. I keep an eye on the lowest voltages reached and how easily a 20 min charge restores that. When I see it struggling I'll replace it.

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...
Still waiting for my Kona EV delivery - it has only been 9 months.
If it were me I'd see if I could get the new model instead.
 

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I think it's not practical to entirely rely on coulomb counting on a lead-acid because of natural discharge. The lithium-ion traction battery is another story and holds a charge very well over a long term. Those counters are readable and very useful, at least to me. Plus it can do OCV readings while the traction battery is unloaded.

The Kona's 12V battery sensor can log anything it wants 24/7 but no one knows what parameters Hyundai download when the car wakes up usually ever 4 hours. When the car is parked that's a good enough no-load condition after 4 hours to evaluate SoC based on voltage. I occasionally see the car adding an intermediate charge (at 2 hours) when it thinks the battery is low but it's often hours later, well past catching a problem that might cause a failure to start.

12V battery complaints roll in almost every day from owners globally and the blame is often placed on the battery quality, despite no evidence. I would suggest that it's more down to:
1. A door left ajar.
2. Excess BlueLink comms, in several cases because the owner shared the login details with a third party. One owner used an Android emulator and that excessively-polled the car.
3. The battery being already weakened from a previous deep discharge and pushed over the edge again. Many seem to assume that it can be fully recovered by charging it.
4. A "smart" wall charger that repeatedly attempting to initiate a charge session when that is prevented for other reasons.

There's no question that the smallish OEM DIN44 12V battery has only barely enough capacity to handle normal start and shutdown tasks, and the systems cannot detect excessive drains when the car is "off". But, most owners don't have any issues. My 12V battery below is 51 months old. I keep an eye on the lowest voltages reached and how easily a 20 min charge restores that. When I see it struggling I'll replace it.

View attachment 7857


If it were me I'd see if I could get the new model instead.
Thank you Kiwi. All very useful factual informatiom.
Ouch! Why do you say, particularly, that I should ask for the new model? What major advantage does it have? Iam 81 & 7 months old; people are dropping dead dailly all around me. Waiting yet another year might not be a green decision!
 

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Thank you Kiwi. All very useful factual informatiom.
Ouch! Why do you say, particularly, that I should ask for the new model? What major advantage does it have? Iam 81 & 7 months old; people are dropping dead dailly all around me. Waiting yet another year might not be a green decision!
Kiwi, when you say the 12 V battery discharge can be caused by leaving a door ajar; is that really because leaving a door ajar means that the car can't go to sleep properly, causing its system to use curent from the 12 volt battery? Same effect from pinging the car with bluetooth? A single LED, or incandescent bulb should not flatten the 12 V battery quickly, should it?
 

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A single LED, or incandescent bulb should not flatten the 12 V battery quickly, should it?
Ya ever left your dome light on overnight? Oh yah, that'll kill it.

My personal opinion is that the 12V battery on this car is small and weak. 410CCA is certainly the smallest battery I've ever had. Granted, that's plenty enough to start an electric car, but it doesn't allow for a lot of standby current drain. Meaning as the battery ages or if it's abused, it's much more likely to fail. As a Floridian who will be running aftermarket equipment with the engine off, I always have AGM batteries because they tolerate the heat better so I certainly plan on swapping this out for a big beefy mofo. But this is just general experience advice, no measurements taken as of yet. Kiwi clearly has more empirical data than I do so I'd trust them on the topic.
 
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