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Discussion Starter · #1 ·
I forgot the boot open last night, Battery was dead today.
I used a small USB booster to start the car but the battery died right after i turned the car off again.
Took it for a drive, didn't charge it at all (no alternator ofc).
Then i used a 12V battery charger, being the curious creature that I am i plugged in as OBD scanner and started the car (While it was being charged)
12V SOC says 255%???
Now every time i plug in the 12V charger it says the battery is faulty (didn't say that before).
Did i damage the battery by charging it and starting the car at the same time?
It doesn't seem like the traction battery charges the 12V if the 12V is empty, makes sense i guess since the computers in charge have no power to give the command?
Anyone else had this issue?
 

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If 12v battery is empty it cannot switch contactors for traction battery. So it will not top up depleted aux battery.
 

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I forgot the boot open last night, Battery was dead today.
It really is a ridiculous design that simply the leaving the boot open can deplete and damage your 12V battery overnight.
Now every time i plug in the 12V charger it says the battery is faulty...
And it probably is.
Did i damage the battery by charging it and starting the car at the same time?
No, and forget the SoC (aux) reading, it's not applicable. It's needs a proper charge for many hours with a modern battery charger to see if it's recoverable.
 

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Discussion Starter · #4 ·
It really is a ridiculous design that simply the leaving the boot open can deplete and damage your 12V battery overnight.
And it probably is.
No, and forget the SoC (aux) reading, it's not applicable. It's needs a proper charge for many hours with a modern battery charger to see if it's recoverable.
Thank you for the answers!
Do you think this Battery is a warranty case? Super annoying issue that returns again and again.
And a 12V battery should not die or be faulty after 3 years right? (NOV 18 model)
 

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If it’s under warranty then providing you don’t tell them you killed it by leaving the door open you might get somewhere. It’s probably already near the end of its life at about three years old.
 

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Do you think this Battery is a warranty case? Super annoying issue that returns again and again.
And a 12V battery should not die or be faulty after 3 years right? (NOV 18 model)
Well, it probably should be warranty but I'll think it'll be like getting blood out of a stone. It doesn't help that (at least here) finding a generic replacement of the same CMF45L size is difficult.
 

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Thank you for the answers!
Do you think this Battery is a warranty case? Super annoying issue that returns again and again.
And a 12V battery should not die or be faulty after 3 years right? (NOV 18 model)
2 year warranty on the 12v battery, ours died before the two years was up, but by the time we got to the dealership it was 6 days over, didn’t matter because they used the manufacturing date for the two years! Complained to Hyundai didn’t even have the courtesy to reply, truly sick of car manufacturers that just take your money and couldn‘t give a toss afterwards. Every single issue I’ve had has required a fight to get resolved, I will never recommend Hyundai to anyone again.
 

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Discussion Starter · #8 ·
2 year warranty on the 12v battery, ours died before the two years was up, but by the time we got to the dealership it was 6 days over, didn’t matter because they used the manufacturing date for the two years! Complained to Hyundai didn’t even have the courtesy to reply, truly sick of car manufacturers that just take your money and couldn‘t give a toss afterwards. Every single issue I’ve had has required a fight to get resolved, I will never recommend Hyundai to anyone again.
That's messed up using the date on the battery, why not use the date the steel was made for the car to give you warranty on it too.
 

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Took it for a drive, didn't charge it at all (no alternator ofc).
If 12v battery is empty it cannot switch contactors for traction battery. So it will not top up depleted aux battery.
You're both mistaken.

Once the 12V circuit is energised it will be able to close the HV contactors.

Once the HV system is operational (i.e. you can drive it) there is a DC-DC converter which is engaged to charge the 12V battery ...

... however ....

to eek out every metre of range, they 'fiddle' with the times that the DC-DC converter is engaged.

If you saw no charging during your drive, what you are experiencing/witnessing there is the shockingly poor 12V battery management programmed into the car that it doesn't even run the DC-DC charger module even when your battery is completely flat and desperately needs it.

Of course, a single boot bulb should not deplete a healthy 12V battery to flatness. But there is no evidence that it was in healthy condition to begin with.

Put the battery on a desulphation cycle for 48 hours. All will be well (as well as can be expected given the evidentially p!ss poor 12V battery management on your car).
 

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You're both mistaken.

Once the 12V circuit is energised it will be able to close the HV contactors.

Once the HV system is operational (i.e. you can drive it) there is a DC-DC converter which is engaged to charge the 12V battery ...

... however ....

to eek out every metre of range, they 'fiddle' with the times that the DC-DC converter is engaged.

If you saw no charging during your drive, what you are experiencing/witnessing there is the shockingly poor 12V battery management programmed into the car that it doesn't even run the DC-DC charger module even when your battery is completely flat and desperately needs it.

Of course, a single boot bulb should not deplete a healthy 12V battery to flatness. But there is no evidence that it was in healthy condition to begin with.

Put the battery on a desulphation cycle for 48 hours. All will be well (as well as can be expected given the evidentially p!ss poor 12V battery management on your car).
I wonder if the mode you drive in makes any difference?

Eco for instance may eek out the traction batteries power not allowing the 12-volt much if any charging capacity. Likewise, Sport may do the same saving all the power for the drive motor?

Just a thought really, I drive mostly in Eco with the occasional Sport for fun but am thinking of driving in Normal mode now.

BTW, I had a 12-volt die on me in a Leaf, but it was over 4 years old by then and probably overdue for replacement.
 

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I wonder if the mode you drive in makes any difference?

Eco for instance may eek out the traction batteries power not allowing the 12-volt much if any charging capacity. Likewise, Sport may do the same saving all the power for the drive motor?

Just a thought really, I drive mostly in Eco with the occasional Sport for fun but am thinking of driving in Normal mode now.

BTW, I had a 12-volt die on me in a Leaf, but it was over 4 years old by then and probably overdue for replacement.
Interesting - I drive 99.9% of the time in comfort mode and my 2018 car is fine…...
 

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I wonder if the mode you drive in makes any difference?

Eco for instance may eek out the traction batteries power not allowing the 12-volt much if any charging capacity. Likewise, Sport may do the same saving all the power for the drive motor?

Just a thought really, I drive mostly in Eco with the occasional Sport for fun but am thinking of driving in Normal mode now.

BTW, I had a 12-volt die on me in a Leaf, but it was over 4 years old by then and probably overdue for replacement.
I would say yes. If you were a software geek with next to no training/information on lead acid, it'd seem perfectly reasonable to try to 'improve' the range by undercharging the battery.
 

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Discussion Starter · #13 ·
It seems like the little i managed to charge the 12V yesterday was enough to keep it alive until the traction battery decided to top it up.
traction battery has been charging all night and now the SOC says 99% on the 12V.
We drive on Eco 99% of the time with 1% of the time on sports for fun, never seen a reason to drive on comfort since we were never lacking for any comfort and the roads we drive on dont require massive amounts of torque or speed, 80kmh is the max we encounter here.
Ill look for a car charger that can desulfate a battery since mine is a simple one that just charges it.
 

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I forgot the boot open last night, Battery was dead today.
I used a small USB booster to start the car but the battery died right after i turned the car off again.
Took it for a drive, didn't charge it at all (no alternator ofc).
Then i used a 12V battery charger, being the curious creature that I am i plugged in as OBD scanner and started the car (While it was being charged)
12V SOC says 255%???
Now every time i plug in the 12V charger it says the battery is faulty (didn't say that before).
Did i damage the battery by charging it and starting the car at the same time?
It doesn't seem like the traction battery charges the 12V if the 12V is empty, makes sense i guess since the computers in charge have no power to give the command?
Anyone else had this issue?
You're both mistaken.

Once the 12V circuit is energised it will be able to close the HV contactors.

Once the HV system is operational (i.e. you can drive it) there is a DC-DC converter which is engaged to charge the 12V battery ...

... however ....

to eek out every metre of range, they 'fiddle' with the times that the DC-DC converter is engaged.

If you saw no charging during your drive, what you are experiencing/witnessing there is the shockingly poor 12V battery management programmed into the car that it doesn't even run the DC-DC charger module even when your battery is completely flat and desperately needs it.

Of course, a single boot bulb should not deplete a healthy 12V battery to flatness. But there is no evidence that it was in healthy condition to begin with.

Put the battery on a desulphation cycle for 48 hours. All will be well (as well as can be expected given the evidentially p!ss poor 12V battery management on your car).
I dont think its the boot light thats causing the issue, when a door or boot is not fully closed the car does not seem to go to sleep and the car computers continue to pull 300/400watts. This not fully sleeping seems to be the issue. I found some OBD readers left plugged in did the same the reader was not pulling enough power to cause an issue but its polling of the systems were keeping them awake, Result dead 12v next morning
 

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I dont think its the boot light thats causing the issue, when a door or boot is not fully closed the car does not seem to go to sleep and the car computers continue to pull 300/400watts. This not fully sleeping seems to be the issue. I found some OBD readers left plugged in did the same the reader was not pulling enough power to cause an issue but its polling of the systems were keeping them awake, Result dead 12v next morning
I agree. When mine was in the body shop waiting for parts, they left the bonnet open and that flattened the battery. Also, I noticed on the dash cam at the service, the first thing they did when they opened the bonnet was to put a charger on the 12V battery for the duration.
 

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I agree. When mine was in the body shop waiting for parts, they left the bonnet open and that flattened the battery. Also, I noticed on the dash cam at the service, the first thing they did when they opened the bonnet was to put a charger on the 12V battery for the duration.
When the Hyundai engineers from their head office were investigating a software update fault on my car the first thing they did was to connect a booster pack to the 12v battery.
 

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I wonder if the mode you drive in makes any difference?
Yeah, nah, it doesn't sound even plausible. The LDC (that charges the 12V battery off the main battery) won't care what the motor, etc is doing. All energy comes from the traction battery and the 12V system only needs a few hundred watts. In any case, when driving, aux battery charging is fairly minimal with the 196 update, rather it mostly just avoids depleting it.

At the risk of boring everyone yet again with my graph, leaving the hatch ajar rapidly causes a significant depletion of the aux battery. And, to add insult to injury prevents the scheduled charging events from starting. In this short test I've lost 0.5 V in a matter of 40 minutes and it only bounced back halfway when the hatch was closed. My aux battery is 2.5 years old now and still sits at 13.0 V when parked.

144122
 

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Yeah, nah, it doesn't sound even plausible.
How do you figure that!? Your plot precisely proves it, not dismisses it.

It is connected to a 12V bus management system that tells it what to do.

The plot you just put there PROVES it is undercharging the battery. That's a terrible way to charge a lead-acid, 13.0V charging with intermittent pluses. I do not understand what it is trying to do.

It's as if a programmer has been told 'right, programme it like this; only check the 12V every 5 mins, only give the battery a charge if it's below 12.9V, and only for a minute'.

Dreadful.

The reason your battery then shows a major excursion with some minor load is because it is already moderately fook'd.

Thanks for providing the proof of what I've been saying.

Any lead acid held to less than 13.6V whilst also in a load circuit (as you have clearly shown) is going to end up w'kerd eventually, possibly quickly, but it will happen eventually.

Good luck guys, but you've bought a car where the manufacturers seem to know little about these things. Don't take my advice, but perform a long duration charge every few weekends. This will help keep sulphation under control.
 

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How do you figure that!? Your plot precisely proves it, not dismisses it.

It is connected to a 12V bus management system that tells it what to do.

The plot you just put there PROVES it is undercharging the battery. That's a terrible way to charge a lead-acid, 13.0V charging with intermittent pluses. I do not understand what it is trying to do.

It's as if a programmer has been told 'right, programme it like this; only check the 12V every 5 mins, only give the battery a charge if it's below 12.9V, and only for a minute'.

Dreadful.

The reason your battery then shows a major excursion with some minor load is because it is already moderately fook'd.

Thanks for providing the proof of what I've been saying.

Any lead acid held to less than 13.6V whilst also in a load circuit (as you have clearly shown) is going to end up w'kerd eventually, possibly quickly, but it will happen eventually.

Good luck guys, but you've bought a car where the manufacturers seem to know little about these things. Don't take my advice, but perform a long duration charge every few weekends. This will help keep sulphation under control.
However, if that is true and sulphating is the problem they why are there lots of Kona EVs not suffering this problem?
 

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Please correct me if I’m mistaken, but isn’t that graph showing that the AGM is being charged every 4 hours (14.7V) and rest of the time it is idle or with very light load as the charge is decreasing slowly?

Thus, it is not being charged at 13V but it is sitting ~idle practically fully charged.

The voltage drop when opening bonnet leads to higher load to the AGM battery (HV battery out, interior lights come on etc). Even so, the AGM voltage is still above 12.5V which is an ok value.
Bonnet closes and light come off > less load > voltage rises a bit.

 
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