Kona randomly going flat
Discussion
A secondhand story from texts which I'll update later when I get more information.
Sequence of events, my wife plugged our 2023 old shape Kona EV yesterday at approx 16.00 (18% remaining) to charge overnight (Podpoint controlled by Ovo Charge anytime app). It was completely dead with a flat battery this morning. I noticed when I returned last night at 18.30ish while I was putting my bike in the garage that the headlights randomly came on for a minute or so and then went off. In hindsight should have investigated this but didn't. She managed to get into the car manually this morning with the secret key and the breakdown recovery chap (Brittania Rescue not Hyundai) got it going and it seems fine now.
Any ideas how we find out why this happened, is there any way of accessing error codes?
Other information that may be pertinent - every so often a yellow light comes on in the external front Hyundai badge - googling is rather inconclusive, but it seems to be a warning about the battery being too full to charge and sometimes also get similar wording on the screen. This seems odd as we have set it not to charge beyond 90% (should this be 80%?) for battery longevity, but I have never bothered investigating further.
Sequence of events, my wife plugged our 2023 old shape Kona EV yesterday at approx 16.00 (18% remaining) to charge overnight (Podpoint controlled by Ovo Charge anytime app). It was completely dead with a flat battery this morning. I noticed when I returned last night at 18.30ish while I was putting my bike in the garage that the headlights randomly came on for a minute or so and then went off. In hindsight should have investigated this but didn't. She managed to get into the car manually this morning with the secret key and the breakdown recovery chap (Brittania Rescue not Hyundai) got it going and it seems fine now.
Any ideas how we find out why this happened, is there any way of accessing error codes?
Other information that may be pertinent - every so often a yellow light comes on in the external front Hyundai badge - googling is rather inconclusive, but it seems to be a warning about the battery being too full to charge and sometimes also get similar wording on the screen. This seems odd as we have set it not to charge beyond 90% (should this be 80%?) for battery longevity, but I have never bothered investigating further.
I've heard of Hyundai/Kia group cars having issues with being polled by a third party, which results in the 12V battery going flat at least due to the car waking up constantly.
It's part of the same reason why their cars aren't directly compatible with the like of Octopus Intelligent Go, and to utilise that tariff, you need a compatible charger instead which handles the polling from the energy company. Not sure how the OVO Anytime works, but I'm wondering if they have a similar issue that polls the car and causes it to wake up constantly and result in the flat battery (12V).
However, I'm not sure how relevant this is as I assume the flat battery is referring to the high voltage battery used to power the car rather than the accessory battery.
It's part of the same reason why their cars aren't directly compatible with the like of Octopus Intelligent Go, and to utilise that tariff, you need a compatible charger instead which handles the polling from the energy company. Not sure how the OVO Anytime works, but I'm wondering if they have a similar issue that polls the car and causes it to wake up constantly and result in the flat battery (12V).
However, I'm not sure how relevant this is as I assume the flat battery is referring to the high voltage battery used to power the car rather than the accessory battery.
My 18 plate used to do this often, and for no apparent reason.
Some say it's one of the doors not being shut properly, or one of the ECU's not going to sleep.
Mine was pre app, so no polling the internet.
We ended up with a 12V booster pack in the boot, which we could use to get the car relay's to open the main traction battery.
We also used to use a small solar panel, connected direct to the 12V battery if we left the car for 2+ weeks.
Some say it's one of the doors not being shut properly, or one of the ECU's not going to sleep.
Mine was pre app, so no polling the internet.
We ended up with a 12V booster pack in the boot, which we could use to get the car relay's to open the main traction battery.
We also used to use a small solar panel, connected direct to the 12V battery if we left the car for 2+ weeks.
kambites said:
Don't they use the traction battery to top up the 12v battery when the car is left idle? If not, why not? It shouldn't be hard to monitor the voltage of the 12v circuit and temporarily engage the traction battery to charge it if it drops below a certain level?
I think the traction battery top up of the 12v is similar to an ICE car, in that the recharging of the 12v only happens when the car is 'on'.So, if the 12v is losing power when the car is off, it may be below operating voltage when the car is switched on, and that's when they throw up weird errors.
Introducing a system to top up the 12v when the car is 'off' could compromise the traction battery where the car is left for a lengthy period and there's a 12v system fault drain.
Edited by Paul Drawmer on Saturday 23 November 06:43
We have a 2021 Kona. The badge light is to indicate there is high voltage under the bonnet.
Basically, the car trickle charges the 12v battery automatically while you drive - It also checks the 12v system periodically while it's locked/asleep.
If it thinks the 12v battery is low, it will trickle for an hour or so and the led will come on to show that - all normal behaviour.
However, there are issues with all hyundai 12v charging systems.
My kona is 3 yr old and still on its original 12v battery, never had an issue with a flat battery. It's been a pretty reliable car. Couple of early niggles but on the whole I'm happy.
I also have an Ioniq 6 - It's 1 yr old and is on the 2nd 12v battery after the first one died - it went flat about once a week until I took it in and had it swapped.
Thank god for 5yr warranties - I have a feeling I'll need it on my i6. Its had a few warranty repairs already and another one scheduled in.
Get all the software updates you can from the dealer.
Basically, the car trickle charges the 12v battery automatically while you drive - It also checks the 12v system periodically while it's locked/asleep.
If it thinks the 12v battery is low, it will trickle for an hour or so and the led will come on to show that - all normal behaviour.
However, there are issues with all hyundai 12v charging systems.
My kona is 3 yr old and still on its original 12v battery, never had an issue with a flat battery. It's been a pretty reliable car. Couple of early niggles but on the whole I'm happy.
I also have an Ioniq 6 - It's 1 yr old and is on the 2nd 12v battery after the first one died - it went flat about once a week until I took it in and had it swapped.
Thank god for 5yr warranties - I have a feeling I'll need it on my i6. Its had a few warranty repairs already and another one scheduled in.
Get all the software updates you can from the dealer.
kambites said:
Don't they use the traction battery to top up the 12v battery when the car is left idle? If not, why not? It shouldn't be hard to monitor the voltage of the 12v circuit and temporarily engage the traction battery to charge it if it drops below a certain level?
Is that possible? My limited understand of batteries lead me to believe you need considerably more than 12v to charge a 12v battery, which is why alternators run at between 13.5 and 14.5 volts. If asleep, I believe Hyundai's won't charge the 12V battery if the traction battery is below 20%.
Our 2020 Kona did this several times and Hyundai replaced the battery. (We also had a new heat pump, main info screen, 2 door locks and several other things. It must have had £10k in warranty work in the first 18 months.)
As has been said, you need to open the bonnet with the key and use a starter pack to switch it on. It will then charge as you drive, or else you can just charge the traction battery to above 20%.
My BIL Ioniq 5 had the same issue.
Our 2020 Kona did this several times and Hyundai replaced the battery. (We also had a new heat pump, main info screen, 2 door locks and several other things. It must have had £10k in warranty work in the first 18 months.)
As has been said, you need to open the bonnet with the key and use a starter pack to switch it on. It will then charge as you drive, or else you can just charge the traction battery to above 20%.
My BIL Ioniq 5 had the same issue.
dave01253 said:
We have a 2021 Kona. The badge light is to indicate there is high voltage under the bonnet.
Basically, the car trickle charges the 12v battery automatically while you drive - It also checks the 12v system periodically while it's locked/asleep.
If it thinks the 12v battery is low, it will trickle for an hour or so and the led will come on to show that - all normal behaviour.
However, there are issues with all hyundai 12v charging systems.
My kona is 3 yr old and still on its original 12v battery, never had an issue with a flat battery. It's been a pretty reliable car. Couple of early niggles but on the whole I'm happy.
I also have an Ioniq 6 - It's 1 yr old and is on the 2nd 12v battery after the first one died - it went flat about once a week until I took it in and had it swapped.
Thank god for 5yr warranties - I have a feeling I'll need it on my i6. Its had a few warranty repairs already and another one scheduled in.
Get all the software updates you can from the dealer.
We were looking at the Ioniq 6, so it's disappointing to hear about the woes you've had with yours. Hard to find a decent idea on what they're like as they've seemingly sold so few over the last couple years.Basically, the car trickle charges the 12v battery automatically while you drive - It also checks the 12v system periodically while it's locked/asleep.
If it thinks the 12v battery is low, it will trickle for an hour or so and the led will come on to show that - all normal behaviour.
However, there are issues with all hyundai 12v charging systems.
My kona is 3 yr old and still on its original 12v battery, never had an issue with a flat battery. It's been a pretty reliable car. Couple of early niggles but on the whole I'm happy.
I also have an Ioniq 6 - It's 1 yr old and is on the 2nd 12v battery after the first one died - it went flat about once a week until I took it in and had it swapped.
Thank god for 5yr warranties - I have a feeling I'll need it on my i6. Its had a few warranty repairs already and another one scheduled in.
Get all the software updates you can from the dealer.
Perhaps next year's refresh will increase that sample size.
2022 Kona here. Graphs below from my 12v battery monitor show it's charging behaviour when idle. Charges the 12v for 20 mins every 4hrs when it needs it. Once it can hold a high level of charge without dropping this reduces to once every 24hrs.
As stated the traction battery will not charge the 12v if below 20% however it ought to do so anyway while the 64kWh traction battery is charging.
As stated the traction battery will not charge the 12v if below 20% however it ought to do so anyway while the 64kWh traction battery is charging.
5s Alive said:
2022 Kona here. Graphs below from my 12v battery monitor show it's charging behaviour when idle. Charges the 12v for 20 mins every 4hrs when it needs it. Once it can hold a high level of charge without dropping this reduces to once every 24hrs. ...
That's an interesting graph. Please tell, what Battery Monitor is that?Paul Drawmer said:
That's an interesting graph. Please tell, what Battery Monitor is that?
This one, was less expensive when I got mine but don't think it was from Amazon. It's been working fine for over two years now. It can take a minute or so to transfer the stored data to your phone if it hasn't been done for some time as it records the last 30 days of voltage readings. Also does the usual cranking voltage test on ice vehicles.https://www.amazon.co.uk/Battery-Monitor-Campervan...
thisnameistaken said:
Is that possible? My limited understand of batteries lead me to believe you need considerably more than 12v to charge a 12v battery, which is why alternators run at between 13.5 and 14.5 volts.
The traction battery pushes out a bit more than 14.5 volts - a few hundred more 
Discombobulate said:
thisnameistaken said:
Is that possible? My limited understand of batteries lead me to believe you need considerably more than 12v to charge a 12v battery, which is why alternators run at between 13.5 and 14.5 volts.
The traction battery pushes out a bit more than 14.5 volts - a few hundred more 
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