Hyundai/KIA 12V battery issues

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Nagaman
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Hyundai/KIA 12V battery issues

Post by Nagaman »

U.k. YouTuber Andrew Till has had his Ioniq 5 suffer a flat battery already…….his e-Niro did the same. Seems an odd weakness. https://youtu.be/A4NUdNWyocM
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Re: Hyundai/KIA 12V battery issues

Post by sleeperpservice »

The original Ioniqs suffer this frequently too even with the tech that's supposed to keep them topped up.

Don't quite know how it's happening with the 5 as well.

The battery in ours is tiny but have had no problems with it.
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Re: Hyundai/KIA 12V battery issues

Post by AusKona »

There is a topic on this as it applies to the Kona over at insideevs

If you're interested you can get the same monitor rebranded to Matson from Supercheap

I have installed a Matson on my Kona. It is quite interesting to see how the 12V charging system behaves and FWIW, in the 2021 model Kona the flat 12V battery issue seems to have been solved.
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Re: Hyundai/KIA 12V battery issues

Post by T1 Terry »

My ex taxi Prius suffered this problem, until I replaced the lead acid battery with a 4 cell LFP battery, rarely see the problem occur now and only if it has been sitting for a few weeks not being driven. The fix in my case would be to disconnect the battery if the vehicle is to be parked under cover for a few weeks, or a small solar panel connected across the battery with a 13.6v cut out.

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Re: Hyundai/KIA 12V battery issues

Post by doggy »

Hi Terry,

I'm curious how this LFP has worked out for you.

I was considering replacing my Zoe battery with one but chickened out and opted for an AGM instead.

My reason for not doing it was worry about the DC-DC converter when the LFP BMS cuts out the charge. That effectively open circuits the DC-DC converter (with the exception of any operational vehicle loads). It would likely be a diode-killer with an alternator but a lot would depend on the design of the DC-DC converter. One would hope that it would not mind being open circuited and indeed is probably a Buck converter (which should be okay O/C).

Thoughts?
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Re: Hyundai/KIA 12V battery issues

Post by Jarrad »

I got a flat battery not so long ago, which was a combination of a faulty 12V (low charging voltage) and packing for a trip (interior light was on for a while :? ) Although it was an easy fix (jump start, then new 12V battery), it's frustrating when you have a main battery fully charged but you're dead in the water with a flat 12V.

The weakness in the system is the top-up charging of the 12V from the main battery is (I believe) scheduled, rather than on-demand / as-needed.
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Re: Hyundai/KIA 12V battery issues

Post by Peter C in Canberra »

This was an issue in the Kona for which there were updates to do more 12V topping up. It is astonishing that it is still a problem in the Ioniq 5. It should be sorted by now. The 12V lead-acid battery should last a very long time. It never has to do any cranking. It should be sitting on a perfect float charge all the time. All it has to do is turn on some electronics, including the electronics that provides it with a charge. Perhaps they are using a really crappy battery. Alternatively, the 12V charger is not turning on often enough.
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Re: Hyundai/KIA 12V battery issues

Post by doggy »

Peter C in Canberra wrote: Wed, 09 Nov 2022, 14:22 This was an issue in the Kona for which there were updates to do more 12V topping up. It is astonishing that it is still a problem in the Ioniq 5. It should be sorted by now. The 12V lead-acid battery should last a very long time. It never has to do any cranking. It should be sitting on a perfect float charge all the time. All it has to do is turn on some electronics, including the electronics that provides it with a charge. Perhaps they are using a really crappy battery. Alternatively, the 12V charger is not turning on often enough.
Actually the ones in the Leaf, the Zoe, earlier Teslas and possibly many EVs are all cranking batteries. They really are not designed for this type of service and I suspect they simply sulphate. My Zoe one developed a very strange fault when about 4 years old. Tesla now fits NMC Lithiums (LFP would have been better because the utility outlet can go to 16.8V- 4*4.2V). I have AGM in my Zoe and it is designed to be floated and I expect a much longer life (but it is heavier and more expensive than the cranking batteries with thin plates). I suspect the manufacturers just go for "cheap and easy" and it is not normally them who have to pay for the replacements. Dealers charge an arm and a leg (something like $480 for a Nissan "EV Battery" as fitted to the Zoe.
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Peter C in Canberra
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Re: Hyundai/KIA 12V battery issues

Post by Peter C in Canberra »

I think it is probably just an ordinary cranking battery off the shelf for the Hyundais too. This stuff just shouldn't be hard!
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Re: Hyundai/KIA 12V battery issues

Post by doggy »

Peter C in Canberra wrote: Wed, 09 Nov 2022, 14:39 I think it is probably just an ordinary cranking battery off the shelf for the Hyundais too. This stuff just shouldn't be hard!
I think some EVs use the 12V system for some heavy duty stuff (like aircon or power steering). I know the Tesla and Zoe use the traction battery ~400V for this sort of stuff but I have heard some cars use 12V for some heavy loads. That would shorten the life of the 12V battery.

Yep, likely they (Hyundai) just do what the others do. In theory, one could fit an LFP 12V battery but there could be several issues:

1. Void warranty
2. It would have to have an internal BMS and cell protection plus FETS to cut charge and discharge.
3. It is possible that the car's DC-DC converter might not like an open circuit under load if the LFP suddenly disconnects charging. On the other hand, DC-DC converters from the traction battery would likely be Buck Converters which should not have a problem.
4. Higher cost.
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Re: Hyundai/KIA 12V battery issues

Post by Peter C in Canberra »

doggy wrote: Wed, 09 Nov 2022, 15:16 I think some EVs use the 12V system for some heavy duty stuff...
Even so, it still should not be hard for the 12V battery. Those loads should be handled by the DC-DC converter with the battery only doing a little buffering. I gather the DC-DC converter in the Kona is good for 1.5kW and the converter should be beefy enough to at least cover the average of 12V loads when lots are running simultaneously.
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Re: Hyundai/KIA 12V battery issues

Post by doggy »

The fact is that these batteries fail in a range of different EVs and relatively quickly.

A GEL or AGM or LFP would have a better profile than a cranking battery.

On top of that, it seems likely that charging of those batteries is not handled particularly well.
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Re: Hyundai/KIA 12V battery issues

Post by coulomb »

doggy wrote: Wed, 09 Nov 2022, 14:33Tesla now fits NMC Lithiums (LFP would have been better because the utility outlet can go to 16.8V- 4*4.2V).
So 15 V nominal (4 x 3.75 V). By the end of the decade, starter batteries might be a specialist application, with the majority of new cars not having a starter motor. I suppose starter batteries will live on for outback trucks for a while. I wonder if the new 12 V standard for cars will be 12.8 V (4 x LiFePO₄), or 15 V (4 x ternary lithium, or perhaps high voltage LFP variants). By then, the majority of highly voltage sensitive auxiliary loads (incandescent bulbs) should be gone.
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Re: Hyundai/KIA 12V battery issues

Post by KiwiME »

My Kona's original 12V battery is still working fine after 4 years but I do monitor it closely with a voltage logger. It gets stressed more during services at the dealer, especially during BMS updates where the traction battery cannot assist. But it's never been under 11.8V, see image below during Campaign 196 where more-detailed traction battery monitoring was introduced.

If I were to modify anything I'd go for fitting a larger size in AGM rather than another technology. But I doubt the LDC would care about a sudden loss of load given the approx 14 amps already drawn by the overall system, and that when the 12V battery is fully charged it's drawing only about 0.1 amp.

It's more a matter of making a significant change to a part without fully understanding the overall system.
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Re: Hyundai/KIA 12V battery issues

Post by Bryce »

Hi there - having earlier this year replaced both my Kona electric and partner's Zoe batteries at pretty much exactly three years old for both, can attest to EVs chewing their 12V batteries. (Both cars started exhibiting random errors, checked the voltages and found them to be low when not running. Conveniently - they did it at the same cold period so I got a bulk deal: they take the same battery!)
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Re: Hyundai/KIA 12V battery issues

Post by doggy »

Interesting that Leaf, Zoe and Kona all have the same battery!

I still have my replaced battery. Here are some interesting things about it:

1. It can still deliver about 75% of the CCA. When you open the Zoe driver door, the car hits the battery with a short 80A drain and uses this to signal good/bad-12V on the CAN bus. My battery can still do this with little droop. So Zoe thinks good though I know bad.

2. It has become very charge inefficient. I forgot the percentage I measured, but it is not good (maybe 60%) and affects the overall driving consumption because of extra drain from the traction battery.

3. It loses considerable SOC on a daily basis- just sitting disconnected. Several % per day.

4. Despite all this I am using it to power a spot welder, which it does very well. So a good second life.
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