12V battery

[KiwiME]

I don't have BlueLink as it's not available here but I'm quite certain that leaving the hatch or a door open could easily drain the 12V battery over a few hours. Even worst, as noted many times before an open door disables the 4-hourly charge events as does leaving SoC under 40%.

I check my prior 24-hours voltage log every morning and I'm starting to conclude that the DIN44 capacity is too marginal as it leaves no room for making common mistakes. Several short trips in a row leaves the battery somewhat discharged and it's highly vulnerable to any following additional loads.

I've recently looked at increasing the battery size but there is only one available that is 30mm longer without causing width or height issues. I would have to modify or redesign and construct a new battery tray, not very appealing options.

*****

Regarding Tesla's M3/Y change to a lithium-ion-based 16V system (mentioned above) I had more information provided by a YouTube channel Ingineerix. Both him and John Kelly (Weber Auto) as best as I'm aware are technical experts on Tesla's technologies yet they disagree on how it works. Ingineerix does not accept that the 16V battery is supported continuously by the traction battery and says that the standby system loads have been brought down such that the 16V battery can handle them for a suitable period that does not over-cycle the HV contactors. Only when the park cams are used does the HV help out. Relevant comments are at the top of the list under those links.

Kona below:

 

[Toolworker]

My battery has gone down to about 5V twice since my last software update in January. Once after the hood was open overnight and once after the hatch was ajar overnight. On other cars this wouldn't have drained the battery so drastically so I am wondering if this is bluelink panicking? I have never enabled bluelink but maybe the dealer did for their software update? IDK, but how does one check to see if bluelink is active, and if so how do I turn it off?

This happened to me yesterday.

​

I left the hatch open the afternoon of May 16, and the car unplugged. I assumed that after a short time, the car would turn off all lights and 12v systems like any normal vehicle. But our Hyundais are more creative than that! The open hatch kept things going for about an hour.

Then every four hours when it tried to charge the 12v battery, the car systems woke up, including the open hatch, the charge algorithm took a look and decided not to get involved, and things ran for another hour. After the fourth time, there wasn't enough left in the 12v battery to turn systems on.

At 4 pm I found the corpse and revived it with my 12v jumper pack. First thing I did was to close the hatch, then remembered the jumper pack was in the back. But I always leave it up against the back of the rear seat, for just such a situation.

 

[Ferenc Jakab]

I don't have BlueLink as it's not available here but I'm quite certain that leaving the hatch or a door open could easily drain the 12V battery over a few hours. Even worst, as noted many times before an open door disables the 4-hourly charge events as does leaving SoC under 40%.

I check my prior 24-hours voltage log every morning and I'm starting to conclude that the DIN44 capacity is too marginal as it leaves no room for making common mistakes. Several short trips in a row leaves the battery somewhat discharged and it's highly vulnerable to any following additional loads.

I've recently looked at increasing the battery size but there is only one available that is 30mm longer without causing width or height issues. I would have to modify or redesign and construct a new battery tray, not very appealing options.

Hi KiwiMe, My 12V battery died on a remote track in the Lower Glenelg National Park, at dusk. It had probably been reverse jumpered by a roadside assist tech. I've mentioned this in a post elsewhere. We were hampered by our GPS proximity to the South Aus border and we literally had to listen to RAA and RACV argue for an excruciating hour about whose responsibility we were. SA won and the same tech who "helped" last time was sent to our rescue. Any way, next morning after our adventure and leaving the 12v battery on charge all night I drove to Mount Gambier and bought a new battery. Wasn't going to wait for a week for Hyundai to get one in. I've posted a pic of the one we bought. It has more CCA than the old one but not sure about the other stats. It's an NZ company if this battery is of interest.

 

[electriceddy]

Thanks a million EE! My bluelink is off, good to know. I'll take your advice and put it in utility mode occasionally and before any service. To get the car to turn on again, both times I needed to use my 12V charger (which will live in the car now just in case). Voltage across the 12V battery terminals after the charge is exactly 12V, similar to what I see on Knoa's inspections. I think I should consider replacing the battery proactively. I'll read some of the posts here for recommendations.

Glad the info was helpful,
This link will guide you to all relevant threads concerning 12V battery operations and replacement

 

[Ferenc Jakab]

This happened to me yesterday.

​

I left the hatch open the afternoon of May 16, and the car unplugged. I assumed that after a short time, the car would turn off all lights and 12v systems like any normal vehicle. But our Hyundais are more creative than that! The open hatch kept things going for about an hour.

Then every four hours when it tried to charge the 12v battery, the car systems woke up, including the open hatch, the charge algorithm took a look and decided not to get involved, and things ran for another hour. After the fourth time, there wasn't enough left in the 12v battery to turn systems on.

At 4 pm I found the corpse and revived it with my 12v jumper pack. First thing I did was to close the hatch, then remembered the jumper pack was in the back. But I always leave it up against the back of the rear seat, for just such a situation.

Having had similar experience I have pulled the plug to disconnect the bonnet sensor and installed a switch to turn off the light in the boot.

 

[OzKona]

Interesting discovery today...

March 2021 Aussie Kona 64kWh Highlander. I went to the car and found the boot was not properly closed and an instrument cluster warning reporting same. The car was in our garage, unlocked, and had been in this state for 24 hours. Contrary to most reports in this thread, the 12V battery was not dead flat and the car started normally. No Bluelink here in Oz.

I measured the battery voltage, 12.1V. When I started the car the voltage went immediately to 14.6, indicating charging, mimicking an ICE car and exactly what you'd expect.

 

[Ferenc Jakab]

Lucky you OzKona! 12.1 is marginal so if you have a problematic battery the story might be different. I had left things open deliberately on multiple occasions without problems, before the first flat battery event.

 

[KiwiME]

Having a BM2 log would have nicely illustrated that interesting event. I’m not brave enough to test it myself in the interest of science as I’m nursing my 12V Rocket battery into old age.

 

[KiwiME]

It may not have gone dead, but for sure lost a lot of charge. It is a good idea to connect an external charger to recharge it to full again as soon as possible. Relying on the car to recharge it may not be enough.

(Quoted from the other thread), I believe the car can provide enough of a kick and that’s best done with a traction battery charge of at least 30 minutes, rather than Utility Mode,

 

[OzKona]

Having a BM2 log would have nicely illustrated that interesting event. I’m not brave enough to test it myself in the interest of science as I’m nursing my 12V Rocket battery into old age.

Your wish is my command, Sir.


At 1335 the car was started and my wife took a short shopping trip. The second spike around 1400 is when she started the car to come home.

On arriving home it appears the boot was left not properly closed (not by her, I hasten to add, she knows better than that, but by a tradie who lifted a heavy object out of the boot for her).


The rest of the 24 hour period continues the next day.....

At 1231 I started the car to check on the behaviour of the smart cruise control (discussion over on SpeakEV), which I couldn't do in the garage because "SCC conditions not met" was displayed on the dash. I did not feel like going for a drive to meet SCC conditions, so shut the car down. It was during this time that I noticed the "boot open" warning. I closed the boot and then did the voltage checks with a multimeter.

I reported above that the voltages were 12.1 at rest (the lesser of the two dips around 1311 on the graph)and 14.6 when I started the car. The car was on for less than the battery monitor's two minute reporting interval so that spike was not captured and does not appear on the graph. Also, the peak voltage was 14.23, not 14.6 as I reported.

At intervals the BM2 is reporting battery level at 32%

It may not have gone dead, but for sure lost a lot of charge. It is a good idea to connect an external charger to recharge it to full again as soon as possible. Relying on the car to recharge it may not be enough.

(Quoted from another thread)

At about 1627 I connected a Ctek MX 7.0 charger in its conventional wet cell mode. The spike to 14.67 volts is the charger doing its thing to determine if desulphation is necessary. It then settled into its Bulk charging mode (constant current), which on this model is 7 amps. You can see at the end of the trace the voltage rising as the battery accepts charge.

Question: What are the dips occurring every 4 hours from about 2030 on May 20 to about 0830 on the 21st? (I suspect I interrupted another one with my unsuccessful SCC test at 1231 on the 21st.)

 

[Toolworker]

Question: What are the dips occurring every 4 hours from about 2030 on May 20 to about 0830 on the 21st? (I suspect I interrupted another one with my unsuccessful SCC test at 1231 on the 21st.)

As mentioned above, these are probably the Hyundai algorithm trying a periodic 12v battery charge, noticing something out of the ordinary, and giving up - but not before waking up the car's systems so they can suck another chunk out of the 12v battery before going back to sleep.

 

[C02less]

Just to conclude (hopefully) my 12V battery expierience of a few days ago: My battery went dead twice in two days last week. Once overnight and once after being parked for less than an hour. Less than 8V across the battery terminals. Once I jump started it and there were a few sparks when making the final connection (short circuit?). I replaced the 12V battery 4 days ago with one from NAPA (OEM battery is off warranty) and all is well so far. I kept the original battery and it is holding a steady 12.5V. I will pick up a NOCO GB40 battery booster for peace of mind for some road trips in the next month.

I did contact the service manager who admitted there were many 12V battery problems and usually changing the battery solved everything. He is probably right but I am wondering why the original 12V battery discharged in the car, but holds a charge since it was removed from the car. An intermittent short circuit? Time will tell... I will update if there is more wrong than just the battery.

Rant: I have never had a battery fail in less than 5 years, why are so many hyundai oem batteries failing in 2-ish years? Overall I am very happy with the car, but the oem battery and oem tires needed premature replacement - an extra cost passed along to the customer.

 

[Toolworker]

... I am wondering why the original 12V battery discharged in the car, but holds a charge since it was removed from the car. An intermittent short circuit? Time will tell... I will update if there is more wrong than just the battery.

Rant: I have never had a battery fail in less than 5 years, why are so many hyundai oem batteries failing in 2-ish years ...

There are two causes, one technical and one corporate.

The technical flaw is that various situations arise in which the Hyundai vehicle puts repeated loads on the battery and interrupts periodic charging.

The corporate flaw is that this well-known problem, and others, still persist because when customers try to call problems to Hyundai's attention, the company has a record of failing to address them. I wonder whether Korean culture may make it difficult for an employee to bring a problem to their management. Cf. discussion about the possible role of Korean culture in the 2013 crash of Asiana Flight 214 at SFO.

The battery holds a charge when removed from the car because it's no longer attached to a vehicle that drains it.

 

[C02less]

So the replacement battery from NAPA has been in for exactly one week and working fine until this morning. The dashboard lit up, but the battery warning light was on and car wouldn't go into gear. Also, utility mode disappeared from my menu. I switched the car off and checked the battery - still had 12V across the terminals. Switched the car on again and it started up normally. Utility mode reappeared so I am leaving it in utility mode for 15 minutes before heading out.

I charged to 80% last night after a road trip yesterday, so the problem isn't short trips. Also, no doors were left open. I am very careful with that now.

I'll inform the dealer. Any other ideas?

PS> I read (OK skimmed) most of this thread yesterday. My hat is off to those contributors who are figuring out Hyundai's problems on their own time!

 

[electriceddy]

I'll inform the dealer.

That would be the prudent thing to do at this point.
I suspect a defective EPCU

or a phantom drain of some type, hard to tell w/out BM2 monitor.
One question, have you measured the voltage (battery in and car running) should be at least ~ 13.2V, and in utility mode ~14.6V.
BTW short trips are good, as the top up schedule resets once parked and off

 

[C02less]

Thanks EE! Battery voltage with car running is approx 14V, about the same in utility mode. My Voltmeter is an old cheap analogue unit so the scale can be read accurately only to 1V increments. If this problem persists I might need to invest in a better one. New battery + boost box + new voltmeter - yikes the cost of fixing my new car still on warranty is getting expensive!

Thanks for the heads-up on the EPCU. I have not done my EPCU seal recall yet due to some schedulling problems between me and my dealer. So if it's leaking that would explain a lot, but I am speculating at high speed here and need to slow down. Another thing for the dealer to check.

 

[C02less]

So I had the car at the dealership today. They claimed to have a reset procedure to fix this problem. In my own words repeating what I understood they said: by unplugging the main fuse block and plugging it back in various systems are reset. Before the unplug/reset there was 500mA through the main fuse block with everything off, and afterwards it was 100mA. I am not sure what the normal reading is but it sounds like a significant reduction. The mechanic also searched for other faults and did not locate any. They also did the EPCU recall. So wish me luck on my 2000km road trip next week.

PS> They had a Hellcat on the lot today but they wouldn't let me take it as a loaner. Even though I asked nicely.

 

[KiwiME]

Although it's become abundantly clear that the main defect in Hyundai's auxiliary battery design is that the Kona's 12V 45Ah battery is not able to request back-up 'on demand', I have noted that the normal 'parked' charge schedule of 20 minutes every 4 hours does seem to do a good job of keeping the battery healthy, the OEM 'Rocket' now in its 5th year.

Meanwhile my ICE car doesn't seem to do as well, with being used once every 2 weeks at most. So, after trying a 5W solar panel supplemental charger for about a year which only works well in summer, I've now rigged up a mains charger that emulates Hyundai's method. It's just a 12V-3A power supply adjusted to about 15 V to overcome voltage drop in the 7 m of wire leading to the ICE car battery. It's on a mechanical timer set to 15 minutes every 4 hours. The ICE has a circuit that only connects the wire to the battery when the voltage offered exceeds 14.4 V and disconnects when it's under 13.3 V. That avoids the slight drain back into the PS when it's off, although frankly a simple Schottky diode may have worked just as well.

Just like the Kona the battery it holds a surface charge voltage above 12.8 V in between charges.

 

[hobbit]

100 mA is still too much for full quiescent shutdown. It should be more like 10 - 15. But you have
to wait like 20 minutes for the car to reach that state. And if someone's trying to measure very
small DC currents with a Hall probe, that could be wildly inaccurate. A bit of hackery with test
leads is needed to insert a real ammeter but not actually break the 12V connection to the car,
and get to stop complaining that the hood is open.

_H*

 

[Ferenc Jakab]

100 mA is still too much for full quiescent shutdown. It should be more like 10 - 15. But you have
to wait like 20 minutes for the car to reach that state. And if someone's trying to measure very
small DC currents with a Hall probe, that could be wildly inaccurate. A bit of hackery with test
leads is needed to insert a real ammeter but not actually break the 12V connection to the car,
and get to stop complaining that the hood is open.

_H*

Shows the location of the connector plug for the bonnet sensor. I've put red insulation tape on it and partially reinserted it to prevent muck getting into the plug.