IONIQ5 - Mystery of the 12v battery drain solved! - How to avoid this happening in the future.

#hyundai #Ioniq5 #EV #Project45 #12voltbatteryissue
The mystery of the 12v battery drain is solved in this video by monitoring the car for around 7-days with the Battery Monitor BM2 device and app.
Battery Monitor BM2 device 12V Battery: amzn.to/3ZUmvcP
CXY T18 1000 Amp Jump Starter Power Pack: amzn.to/3VPLtGX
00:00 Intro
00:43 How to install Battery Monitor BM2 device 12V Battery
01:19 Battery Monitor 2 app (BM2)
02:06 Reading 7-day graph on BM2 app
03:12 Why the car stop charging the 12v battery
04:02 How to avoid 12v battery drain
OBD2 scanner used in the video: amzn.to/3DNC8H3
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Thanks for watching
James Cheung

[@yanivbalas1]

In Israel they tested in an experiment that the central battery less than 20 percent stops charging the small battery. This is a failure of the engineers

[@LemonTeaLeaf]

Yes I can confirm this now that I've tested it again at 20%. Thanks 👍

[@KaBrook]

I too can confirm this. Ridiculous flaw! It happened to me for the 2nd time today. I noticed my car's settings were all default today though so something tells me Bluelink or an over the air update must've been the culprit this time...

[@av_oid]

Unless you are on a long trip and near a charger before heading off again (or getting home) why would you be going bellow 20% intentionally? If you have an EV you are best having a home charger. And if you have a home charger you should be charging whenever home (or plugged in and scheduled to charge during your off-peak time. He says as much later in the video.

[@jedglover8245]

Interesting findings! My Ioniq 5 12v battery went flat over Christmas. It was sat for four days and was plugged to a 7kw charger at 80%. So something is still amiss with the Ioniq 5 12v battery management. I have since fitted the same battery monitor you have and so far everything is OK, although I have not had the car sit for 4 days since. Which ever way we look at it there is no way the car should let the 12v battery go flat when plugged in!

[@LemonTeaLeaf]

before you started charging was your car below 20%? I'm wondering if the car has already set the 12v not to charge then after your traction battery is topped up it didn't get sent the code to top up your 12v as it still thinks its under 20%?

[@jedglover8245]

@@LemonTeaLeaf I don't believe it was below 20%, I typically keep it above 20% and normally in the 40 - 80% range. While I accept your possible theory, it should really be testing 12v battery level, then check traction battery and charge if above 20%. However your proposition is depressingly possible!

[@johnnyboy7459]

My Subaru Solterra was parked up for 3 weeks prior to Christmas and on my return it was covered in ice and snow. As a precaution I had a battery booster to hand but the car opened and operated as normal. I bought a plug in battery monitor so I could keep an eye on the 12v battery and it shows 14.6 volts when the car is switched on but drops to 12.3 when the car is switched off. After approximately 10 minutes the car gives a low battery warning when the voltage drops below 12v. It mentions in the car manual that when you are doing things in the car that requires power to make sure the car is switched on. The monitor is plugged in to what used to be the cigarette lighter and I find it very helpful.

[@GreggHavens]

So with the batt6V4.ery monitor, when you are driving, the 12V is being charged as needed or a constant 14.6V? I have seen many posts on the charging above 20%or so but not during movement.

[@adrianpike4649]

Thanks James, so the moral of the story is to charge up the traction battery when you get home if the charge level is below 20% 😊

[@LemonTeaLeaf]

Very much so, I would have though it would be still charging the 12v at a lower SOC like 10%

[@st4849]

I heat up the cabin / do manual AC via the app every morning even if I don't need the car that day. This charges the 12V battery on demand for 15min every single day as an addition to the car's built in (not too robust) mechanism - and I never let the charge below 20-30%.

[@LemonTeaLeaf]

Thanks for the tip i suppose you could set the cabin to 17c this way it uses the minimum power for the heater possible. I normally do charge when around 30% but on NYD a mixture of unfortunate events killed the 12v battery.

[@st4849]

@@LemonTeaLeaf The Grinch must have stolen the charge 😂

[@LemonTeaLeaf]

@@st4849 haha Christmas wasn't enough for him!!! 😂

[@charlesodonovan2419]

Excellent commentary and advice James….Thank you.

[@craig2world]

Thanks James, informative as always. In my mind, it should have been designed for this to happen at much lower SOC, maybe around 5%. At those critical times when one is struggling to find a working charger and the SOC is falling though the floor, we are probably relying most on all the peripherals which are powered by the 12v yet this is no longer being topped up by the traction battery leading to an even greater risk of the car being inoperable the longer it takes us to find a charger.

[@LemonTeaLeaf]

Great point! 20% is way to high for it not to charge the 12v battery when it's turned off.

[@johnnyboy7459]

@Gregg Havens. The monitor shows a constant 14.5 volts while driving or stationary. When I turn the traction battery off the monitor shows 12.5 volts but will drop eg if the radio is playing. If I turn the traction battery back on the monitor then shows 14.5 .

[@olafoudgenoeg2679]

Well this is only part of the story because many have dead 12v battery at much higher soc

[@francoisfortin3696]

Great analysys James, as always! Thank you.

[@LemonTeaLeaf]

Much appreciated!

[@ijwilson]

BYD Atto 3 is the same, won't charge the 12V battery if the traction battery falls below 15%. When you consider the tiny amount of power required to keep the battery charged in comparison to the traction battery it should be kept charged until it is no longer safe for the traction battery to do so. Afterall what's the point of having 15% in the traction battery if the car won't start due to a flat 12V battery! Crazy

[@LemonTeaLeaf]

totally and the ioniq 5 is below 20%! I would consider 5% or 10% for it to not charge the 12v seems more reasonable.

[@karencarpenter8275]

Thanks. Very interesting. We have an EV6 and had similar problems over new year. Jan3rd was something of a record day for RAC visiting electric cars that had flat 12v batteries. So if you return home on low charge (

[@LemonTeaLeaf]

It was sub -6 temp that night IIRC as it drain slower when was testing with the battery monitor. I would have thought it would be below 10% and it should be easy enough for them to send a message via bluelink to my phone to say the 12v isn't charging.

[@Investor9872]

Good advice James.

[@royjonzejr]

I wish that I had watched this video a few days ago lol. I drove my Ioniq 5 to the airport to go on vacation for 4 days. I left my car in the long term parking stall with a 9% state of charge. I was wanting to plug it into one of the trickle charge outlets, but the outlet in my stall was broken and I didn't want to spend time looking for a different stall because I didn't want to miss my flight. I thought, "well 9% is kinda low but it should be okay, I'm not gone for that long". 4 days later I came back to a dead car. I actually called a tow truck and had them tow me to the nearest fast charger, incorrectly thinking that I had lost that 9% charge on the big battery over 4 days. Car would not respond when I plugged into the fast charger. That's when the tow truck driver had the idea that maybe it was my 12 volt battery that was dead and he jump started me. Problem solved and my car still had 9% charge just as I had left it.

[@LemonTeaLeaf]

Aw man at least it's a one time thing, well know not keep it below 20% for long periods of time 😄 they need to change it to under 10% SOC 20% seems to high a number. Also I blame bluelink as we've never had that issue with that Kona EV with no bluelink at low SOC.

[@evodessey]

That’s a very interesting Discovery James.

[@LemonTeaLeaf]

Thanks, just seen your video and it was a great find on how to manually set the 12v to charge 👍 anyone reading this and interested click here kzbin.info/www/bejne/kF7EfJWMh7yAgLs

[@RichieKeane]

Should have watched before buying my new charger pack!

[@johnlapointe2922]

The 2021 Kona I recently bought has the 12v battery problem. The 12v has a 400 crank power level. Too low for what is needed. Here in B.C. the local auto parts shop found that a local distributor now has a 600 crank power battery that is the same physical size as the current 12 V battery. So I bought and changed. Vamos a ver!

[@guybrushthreepwood3002]

This happened to me for the first time after 15 months of having our I5. Main battery was at around 17% and left overnight, and car dead in the morning. Got it up and running quite quickly though, and now have a jump pack kept in the froot

[@LemonTeaLeaf]

I suspect it's bluelink sending out coms draining the 12v as our KonaEV doesn't have bluelink and not ran into this issue with the battery below 20%. I Just make sure I'm above 20% if im leaving it overnight.

[@user-cz8bv6sj6y]

Excellent video! What are the requirements for the Bluetooth Monitor? Do the monitors all come with software?

[@EliGrayson]

My Ionic 5 did this today at the most inconvenient time. My mileage was 210 miles to go. I never let my car go below 40 percent. Something else is causing this problem. Hyundai needs to fix this problem. It's to dangerous

[@coniow]

Thank you for this. I have an EV6, and no doubt it will be the same! I usually work on "Down to 20% ==> Charge to 80%" rule, but there will always be times when you go lower.

[@LemonTeaLeaf]

I think i was unlucky with the cold weather, as it seem to last at least a day before it runs down the 12v battery. Still wouldn't leave it below 20% for more than a day or two.

[@a.c.e.7568]

Waste of money! I bought three of these BM2 Battery Voltage Monitors so that I can check on my batteries of my stored/parked vehicles as well as my daily driver in my garage and driveway and I wanted to be able to check them while sitting in my home. The range is about 12 feet as I have to be at my front door to get a signal. This is typical of Bluetooth devices where they state 10 meters or 33 feet but in unobstructed view, but not under a hood shrouded in metal. If I need to be that close to a vehicle, I might as well pop the hood and take a DMM meter to the battery.

[@doug52craig]

I'd read that there was a problem with the bluelink app accessing the car way too many times, the car would wake up then go back to sleep repeatedly causing the 12v battery drain

[@Bawdale]

Yep, the eNiro does the same. When the main battery is below 15% it doesn't maintain the charge of the 12v battery.

[@Lyndalewinder]

Hi James - interesting video but I still have a question. Why would the 12v battery run down from a low level to a level where it would not operate the locks etc. following your return on New Years Day? Lead acid battery voltages don't suddenly drop down - something must have been takiing a load because otherwise it would have sat there for a few hours until your off peak charging kicked in? I understand about the software to charge the 12v battery from the HV battery but I'm not sure this is the full story here.

[@LemonTeaLeaf]

I think you're right something did drain it though I'm not sure what it was as in this video i left without low soc for much longer than NYD only difference was the temp. If it happens again at least I have the monitor to give an idea of what it might be if it acts differently from what it did in this video.

[@timothyi6492]

Whatever it is, it uses a lot of power. I tried trickle charging my 12V battery and the charger couldn't keep up.

[@LemonTeaLeaf]

@@timothyi6492 that definitely sounds more serious than my hickup. Does it charge the 12v when the car is running?

[@timothyi6492]

@@LemonTeaLeaf It has been fine ever since. I think the high drain is normal. It is a 40Ah battery, so to drain it in a couple of days needs about 1A which is slightly more than my charger provides. The car appears to need 12W to run background services, which seems like a lot to me. Keeping BlueLink active and running the various timers should need less than 5W, do I suspect they have gone for the expedient solution as there is theoretically a massive power source available. .

[@olafoudgenoeg2679]

@@LemonTeaLeaf Someone in Sweden found a log file being written to does not get emptied when full and this triggere a loop that causes the battery to drain so fast it cannot be fharged quickly enough and then system is desgined to stop charging the 12v (overheat protection?)

[@Lyndalewinder]

Hi James - just an update on things - over the past three months I've had one of the automatic air vents on the front of the IONIQ 5 replaced because it became intermittent and recently the Integrated Charge Control Unit which is a large liquid cooled box of electronics under the back seat replaced as the car stopped charging on AC. My car is a March 22 RWD so probably made late 2021. The dealer said they had done a few ICCUs. How has yours been?

[@rahula3083]

Have you considered adding a remote battery kill switch (used in old petrol cars having parasitic battery drain)

[@steveurbach3093]

(lead-acid) charge voltage is dependent on cell temps. The colder, the higher voltage needed (why you see 14+. There was snow showing). 12V is not dead. ~10.5V is 'dead'

[@LemonTeaLeaf]

mine went under 4v which cant be good for the battery :(

[@TheAegisClaw]

Shouldn't be an issue, if that's the case there's something else discharging the 12v in less than 24 hours with the car off. That's the problem, not the lack of charging at low SOC.

[@keithgeorge7338]

Hi. Do you not think your 12v has deteriorated. Or maybe low enough for cold weather to be affecting it? The odd few minutes of charging when HV is below 20% shouldn’t be a problem? Voltage doesn’t really indicate health of battery. The 12v is being charged all the time the car is running and when HV plugged in charging. I suppose the unknown is, how many amps is being put into the 12v and if the DCDC provides enough to run all the electrical devices. Some people seem to say the HV is running the heater, but I would assume this is through the DCDC, since everything is 12v? How long a 12v will last on any car, including ICE is unknown. Interesting note, chap with EV6 checking similar 12v battery problems, found the 12v charged when V2L was plugged in, even when car not running, even when HV low. Glad you found a solution to keep HV over 20% and also Solution seems to be to charge the HV every night and make sure you have car running whenever you are sitting in it. My ZS has kept going for 3 years. Been following you from the beginning in the good old Leaf and pleased to see your still at it. Cheers.

[@LemonTeaLeaf]

I found the 12v is charging when the car is on/preheat cabin via app/charged via wallbox or DC charger/in utility mode. I still think the 12v that shipped with the first batch of ioniq 5 are a little dodgy. Thank for following me on my EV journey even after this long! the Leaf is still going strong and it's still on its first 12v battery.

[@keithgeorge7338]

@@LemonTeaLeaf Hi. You could be correct, my ZS EV has been fine from new 3 years, fitted with a German 12v battery, but people had trouble if the original Chinese SAIC brand battery was still fitted. There was suspicion the batteries had drained flat during transit. They introduced an isolation “switch” for transit. No fancy charging system while it’s asleep in an MG! 😂😂😂 Cheers.

[@LemonTeaLeaf]

@@keithgeorge7338 yes my 170 mile home trip after picking up the car I'm sure helped charge the 12v to it's fullest, especially after it's long boat trip from south Korea.

[@sg2007tube]

@@LemonTeaLeaf Do you mean just the cabin heater on would charge the 12V without connected to charger ? If car is charged via wallbox or DC charger this maintains the 12V battery, no need to use cabin heater on top

[@fernandinand]

It's the same on ioniq 38... it's a known issue and the root cause is the short charging period (the spikes). A proper charging would be around 6h.

[@MrNeeds]

Mystery solved indeed, glad we could get to the bottom of that one, thanks for the update James.

[@LemonTeaLeaf]

Thanks, I'm sure they might be more to it than this but I'm happy with the findings.

[@MrNeeds]

@@LemonTeaLeaf seems to make sense, as we discussed in the last video, just a perfect storm for a dead battery.

[@LemonTeaLeaf]

@@MrNeeds Hopefully it wont happen again and if it does the monitor should catch any anomalies

[@olafoudgenoeg2679]

Nothing solved at all because people get dead 12V batteries with the soc over 50%

[@MrNeeds]

@@olafoudgenoeg2679 in this case it’s normal behaviour

[@sebixavier]

Hi james, nice video. The Aux battery gets charges automatically in both Kona and Ioniq. The system measures the SOC of aux battery always (even when the vehicle is off) and charges it whenever it drops to around 12.2V as u showed in the charging graph. At the same time, pls note the Main Electric battery unit will not perform this operation when its SOC is

[@ScubaSteveCanada]

@sidh ... the confusion comes from why Hyundai chose to use 20% as the percentage to stop charging the 12 VDC battery. Much too high of a percentage when the 12 V battery is such a low capacity battery. Hyundai had this problem with the Kona EV too until they reprogrammed it. Not impressed by Hyundai getting too many basic concepts wrong.

[@thomashenden71]

12.2V is too low, this means that the lead acid battery is cycled constantly down to 50-60% SOC which greatly reduces its lifetime. The car actually checks, not constantly, however just every 72 or 12th hour (Ioniq 2020, which I have) (depending on when the battery saver+ function is turned on or not) if the 12V battery needs charging. This means that, especially in the winter, when it is cold and the battery has higher internal resistance, that the voltage is just almost dropped to 12.2 volt when it is time to check, it will drop even further and sometimes too low, for the system to want to charge the 12V battery again. Obviously the sulfatation and damage to the 12V battery accellerates when it is cold. My battery has typically died when the temperature outside fell down to 0 degrees Celcius. The battery saver+ function is just stupid by the way, the 12V battery should be topped up more or less constantly to last long. However Hyundai’s engineers obviously planned for using a LiFePO4 battery which actually is used in the hybrid version of the Ioniq. Very odd that Hyundai neither will correct the situation for 2020-owners and before, or correct this problem in Ioniq 5. This means Hyundai EVs are not reliable in cold climates for the exact stupid reason ICE-cars are not reliable in the winter, the outdated, poor and toxic lead acid battery! :-(

[@davenone7312]

I thought they updated all 12 volt batteries to the AGM type??

[@postmodernrecycler]

I don't understand what drains the 12V battery. I have a 1988 gas car that can sit for 3 months and still start. Leave the Ioniq 5 just overnight on 22% and dead in the morning.

[@adibkozlow2768]

What about dashcams? Would they be part of the problem?

[@kd7lxl]

Does your car have the BMS update they released last year to try to improve this?

[@LemonTeaLeaf]

Yes it has all the latest update from September including the battery condition update.

[@aomurdock]

Step up your game, Hyundai!

[@jimkay2447]

Thanks James just got my brand new Ioniq 5 ultimate on Thursday, picked it up from London and drove the 410 miles to FK6 Your videos have been really useful before I got it after having a 38kwh Ioniq. Maybe one day might see you at the Kelpies 👍🏻

[@LemonTeaLeaf]

Awesome to hear at least your long drive should have topped the 12v up nicely :D You'll find the IONIQ5 isn't as economical as the original IONIQ.

[@FHB71]

I even saw it documented somewhere, that the 12V is only charged if the HV battery is at at least 20% SOC. I looked for it, but cannot find the reference anymore.

[@LemonTeaLeaf]

I hope they change this at some point to 10% SOC as 20% is way to high to stop charing the 12v.

[@mati74]

There must be more to it. I find my 12V battery discharged more or less once every month or so. It mostly (not always) happens after a few days of not using the car. The state of charge of the HV battery is always around 50%. I don't run any apps or other strange things that might consume power. The Ioniq5 simply drains the 12V battery without recharging it. I think it's just bad design. I bought a battery booster and have it in the frunk to kick the Ioniq back into life when this happens. I'm glad this always occurs at home in my garage so nobody can see me starting an electric car with a tool made for old ICE-cars. I actually never needed anything like that before I got the Ioniq5.

[@LemonTeaLeaf]

sounds like the 12v battery could be on its way out. Have you tried getting a replacing 12v from hyundai if it's still in warranty? as that was an issue with our Kona EV. If it still happening after that I'm afraid it'll be somethings deeper. Honestly they really should be using some new tech rather than relying on old 12v ICE battery.

[@mati74]

@LemonTeaLeaf According to my Hyundai dealer, there is nothing wrong with the 12V battery. The car is still on warranty, so they should fix this for free. If there is a fix.

[@LemonTeaLeaf]

@@mati74 I would ask them to swap out the 12v for their demo ioniq5 if they have one as a test. Having a straight swap would at least narrow down possibilities. Also if they agree put a chalk/pen mark on your battery before they do the work, as my old school teacher use to say to us. "It's not that I don't trust you, it's that I know you..." 😆

[@mati74]

@LemonTeaLeaf I have kind of superbad experience with the Hyundai service. Last time I wanted them to investigate this issue, they sent me a bill afterwards because they couldn't find anything. They just concluded that there wasn't anything wrong, thus, no warranty issue, so they wanted me to pay for the work they did. I refused to pay, and finally, they let me go that time. I think I will wait until the battery dies completely, because then, they can't say that there isn't anything wrong. Until then, I'll survive with my 12V booster in the frunk. It's annoying, but not a big deal.

[@GarryMobi]

After about 4 months, I had the dead battery for the first time. Dealer replaced the battery, a week later it was dead again. First results were that the charging voltage while driving was only ~13.5V, but later they also noticed that the car doesn't power down completely when parked, and during that time also draws a lot more power than another I5. Awaiting further infos ... just ordered a booster battery as I don't want to have the car standing at the dealer for currently unforseeable time, nor do I want to get stuck somewhere should it be "fixed" but occur again ... What I noticed up until it died the first time I got 12V SOC info via the API - it appeared to me at that time that it would not actually charge decently while driven, SOC mostly went up while being plugged into the wallbox ...

[@LemonTeaLeaf]

13.5v is too low while driving. from what I've seen with the battery monitor is 14.3v-14.9v when driving. A booster battery seems to be a good call as you don't have to rely on anyone to rescue you. Hope they replace the 12v as it sounds like it's nackard.

[@GarryMobi]

@@LemonTeaLeaf After some pointers from Hyundai and more extensive testing two days ago, the dealer believes they found the problem ... according to them, two problems were found - at one ground connection, the resistance was too high, and additionally the 12V battery sensor calibration was off. Both were fixed, and the car seems to have "behaved" afterwards. I'm picking it up today and see how it goes ... what I have noticed is that after their work, the Bluelink API call once again returns measurements from the 12V battery (it stopped doing that after the first time the battery died - values returned were partially abysmal, like down to 30something percent), I'll see how they turn out now ... currently, it says the battery is at 89% charge (not sure whether they are actually updated while being shut off).

[@Jumpinjackfly-839]

@@GarryMobi Very good point here! I had also drain 2 days ago and since, API returns "False" for the 12V battery % sensor instead of the actual percentage value. Weird. Look like you say that 12V battery sensor became OFF after the incident. Do you know how Hyundai technicians restored and turned the sensor back ON on your car ?

[@steveinoz8188]

Apparently these's been a BMS update to fix this problem.

[@docfink]

This has happened to us twice in the past two weeks, the car not starting both times when my wife was leaving for home after work. The large battery had at least a 40% state of charge but the car had to be jumped both times. It's in the shop now, but this explanation doesn't make sense when the car has the high state of charge ours did. It's a flaw and makes the car untrustworthy. We've had the car since 2/22 without any similar issues until the past month. Why this is happening now is another question I have.

[@simplediagnostics]

I bought mine in 2/2022. I started to get similar issues and 12V battery died after dealer did recall service and software update to battery reconditioning.

[@Nickkenf1]

There is way more to it than this, in fact I don’t think this is really the cause at all. I had a parasitic drain on my 12v in my Ioniq 5 Limited. Check out last weeks video from The Ioniq Guy… he explains the blue link app issue among others, that seems to be the real issue. I had to jump start my car everyday for months, I never let it go below 40 or 50%, so I know that was not the issue. I got so sick of it I sold it January 13th and bought a Tesla Model Y. Sounds like over the last month or two Hyundai has finally solved the problem. I wish I hadent spent 30 hours at the dealership from October to December, cuz I did like the Ioniq 5. Another fix if you have the 12v issue, a $20 Amazon purchase of a remote battery kill switch. Super easy to install and solved my issue. I just figured for $60k, I shouldn’t have to put a bandage on the issue.

[@BFBC2Zocka]

My 12V Battery died while the car was plugged in the wallbox and had 80% SOC... There are many problems in the dealer forums about 12V phantom drain and dead 12V Battery

[@edwardk779]

I noticed that if the traction battery is below 15%, you cannot use the Hyundai app to preheat your car(assuming the car is not plugged in for a charge)

[@LemonTeaLeaf]

Ah yes that happen to us once. Wish it would send a message the mobile to say it's not charging the 12v battery.

[@paulaxford6754]

The Kona won't charge the 12V under 40% SoC. That said, my Kona's 12V battery is going into its 5th year without a single problem. Why is that? Who knows but my early model doesn't have telematics enabled.

[@LemonTeaLeaf]

our early model Kona has zero 12v issue at all. Then again it doesn't have bluelink ether so nothing should be draining the 12v when it's off.

[@Smiler7]

I thought you had to connect the RED wire first, but you connected the BLACK wire first??

[@Yanquetino]

Okay! So avoid letting the car sit at less that 13%, or the 12V risks dying without being topped up from the HV battery. Good to know!

[@andreb.8266]

I think Hyundai have two troubles and I'm not sure they will want to do something about it. The first is the level for the system to charge the 12v batterie, they probably can put a 5% limit unstead of 20% but will they ? The second is more difficult, its an hardware trouble I think. They probably use a switching power supply for the central computer to be able to have Bluelink on all the time and this power supply must need a batterie at 13v to work properly, at 12 and less it cant keep up and nothing work. A proper power supply and a low power circuit need to be made for the future.

[@1silverounce324]

The biggest mystery is why is it discharging so badly. Hyundai is buying mine back because they can’t figure it out. The system is overcompensating by having to charge it so often. The monitoring system will burn out and it won’t charge even above 30%.

[@cbcdesign001]

The stupid thing about this 20% non charge choice by Hyundai's engineers is that, assuming a 25A charge into a 12V battery for 1 hour, that's only a few hundred watts or so whilst there is still a good 11.6kWh of energy left in the 58kWh cell pack, plenty of spare to keep the 12V aux battery charged without killing the main traction battery. That 20% should be lowered to around 3% which is well below where most people will realistically allow the cars energy level to fall to before recharging. They are being FAR too conservative at 20%.

[@Karizma231]

The 12v battery is way too small for a car like that

[@graze2963]

Thats bad news for ppl who cant charge at home, like me. I cant always make shure the car is above 20%...

[@LemonTeaLeaf]

I think the -6c temp didn't help as the second time the 12v lastest for the day before running low.

[@ChrisdyMD]

Actually this isn’t correct. My battery was down to 11.9v when I left it away from my charger for a couple of days, even though the main battery was at 86%. Battery monitor showed car did not charge the 12v battery during this period. I restored it by plugging in the V2L adaptor, which forced a recharge.

[@LemonTeaLeaf]

before you started charging was your car below 20%? I'm wondering if the car has already set the 12v not to charge then after your traction battery is topped up it didn't reset the code to top up your 12v as it still thinks its under 20%?

[@ChrisdyMD]

@@LemonTeaLeaf - No, I made sure the car was well topped up after I last drove it (when the 12v battery was well charged) before I had to vacate my drive for 3 days while I had an electrician doing work in the garage. In fact, apart from one long journey in July, my IONIQ 5’s battery has never been below 20%.

[@flashtheoriginal]

Jesus Lovely car but.... Do I want to spend time agonising over battery life? No. I will wait for a couple of years

[@dablet]

the irony? installing this 12v bluetooth battery monitor will definitely drain your 12v further....

[@JirkaPech]

Ioniq 5 is also not charging 12V when charging cable from wallbox is connected (even if it is not charging)... Got 90% in 800V battery, connected to wallbox, and Got dead 12V 😂

[@sgsuper1150]

Lead acid needs to kept fully charged and is only fully charged after 14.5volt boost. If it drops below 50% it reduces the 500 charge cycle life. I would keep the car on when charging the lithium battery and fix a quick charging cable when the car is off. The battery monitor will drain the the 12 volt.

[@akf2000]

That's my concern, the monitoring itself drains! Like the Heisenberg uncertainty principle!

[@LemonTeaLeaf]

on NYD the 12v drain till it died, but on this ocassion the 12v dropped to 12.24v even with the monitor plugged so I'm not overly worried about it taking some of the power. If it happens again at least I'll have the info from the battery monitor this time to isolate the issue futher.

[@polleyjw]

The monitor should have its own battery, otherwise it can’t provide accurate values. Volt meters have around a one megaohm impedance so they won’t give a wrong reading.

[@LemonTeaLeaf]

@@polleyjw That would make sense as my volt meter takes a 9v battery to run.

[@polleyjw]

I am concerned about size of the voltage drops that you are seeing. Lead acid batteries hold quite a bit of energy and the onboard electronics shouldn’t drain that much overnight. Since so much depends on the 12 volt battery, I would expect the EV would try to keep it charged even down to the low single digits of energy remaining in the traction battery.

[@marcusevjourney566]

Tesla is putting small lithium 15.5 V batteries in its EVs. It is a pity more don't do the same, these old big 12V batteries seem so outdated and don't last so long.

[@LemonTeaLeaf]

I was looking at some of the LiPo and LiFePo 12v battery might be a good replacement if i end up changing out this 12v when it packs in.

[@thelonewrangler1008]

Lithium batteries do not like the cold weather so do your research on the cold rating before you commit to a lithium replacement. They work great everywhere else, they just don't like the cold weather

[@LemonTeaLeaf]

@@thelonewrangler1008 Makes sense why they kept using lead acid batteries. As they wouldn't have preheat option for 12v lithium batteries for the cold weather. I'll keep that in mind.

[@Digikidthevoiceofreason]

This doesn’t solve anything. It just makes the problem more aware. Once Hyundai reprograms the computer to fix this THEN it will be “solved”.

[@johnsammut8540]

You are right but you could have been a bit more gracious. This guy has taken the time to investigate and tell us his findings.

[@robhaitch5544]

He says the mystery is solved.

[@petercittern5898]

I wouldn't hold your breath on Hyundai solving it, they have had about 5 years so far . After my Ioniq 38 went into the dealer four times for flat 12v/ vampire drain, they found a fault in the doors keeping the 12v awake. This improved matters but the same problem kept coming back again and again seemingly randomly and nothing to do with low traction battery SOC. Check out any Ioniq forum it's full of people having the same 12v issues. It's poor software from Hyundai and totally unacceptable. The first thing you want from a car is reliability. I traded mine in as I was sick of it. Reprogramming so as the car charges the 12v several times a day rather than once a day is only a sticking plaster and unacceptable in a 30K car.