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2020 Sonata Hybrid Limited had a completely dead accessory battery while sitting outdoors over 4 days of no use (solar panel equip model)

11K views 41 replies 21 participants last post by  sshus924 
#1 ·
I use my vehicle in a short driving spurt sense normally, only 3 to 5 miles per use typically as I do errands at college; however, I went hiking one weekend like I might normally (a 22 mile drive back to my parking location at night) where I then locked up my vehicle and had no notification from my app of any systems still being on to drain the battery. I came back to my vehicle which had been sitting outdoors with no tree cover above it over 4 days (meaning the solar roof should have charged the traction and accessory battery to full over that period of time) and neither my key fob nor my phone worked for unlocking or communicating with the car. It was dead enough to not have the security light flashing on the dashboard.
Ended up calling roadside assistance where we attempted to remove the plastic cover on the door handle to reveal the mechanical key hole. Even while following the owners manual, the plastic cover would not come off. Even wedged a knife in the gap and it would not budge. The roadside assistance even said that it should be easy to take off which it never did come off (will talk to dealer about that at next service).
Eventually had to wedge and pump the door open and open using a handle wire. As soon as I got into the car, I pressed the 12volt to traction battery self jump button and the car started up like it normally would if it needed a self jump. It has been a few weeks and I haven't had the same issue, so I have no idea if I will randomly have that happen again. The solar roof should in theory, prevent that from ever happening, so it was very disappointing to have that happen with no explanation from Hyundai Customer Care at the time. Wondering if anyone has the same issues.

Reference info:
Car was purchased July 31st, 2020
Had less than 1k miles on it at the time of the incident
one other time I remember the solar panel not being on in the past when the car was parked outside for 5 hours.
Even if the solar panel wasn't on, a car battery shouldn't die in 4 days, especially this new. (could be related to the new technology of the 12volt lithium ion accessory battery and its implementation.
Weather was mild
Cloud cover was very limited
 
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#4 ·
I don't have a hybrid, but I regularly park my car at the airport for a week with no issues. I've often wondered how long I can leave my car parked with the fancy electronics. For example, blue link must always be drawing power. I'd think with the solar panel and the giant battery, it should last even longer. I think you need to take it to the dealer
 
#6 ·
I had the exact same thing happen to me about 30 days after I bought my 2020 Santa FE Sel. Parked the SUV over the weekend and on Monday morning battery was completely dead. There is a trick to getting the plastic piece out so that you can use the key. You have to pull on the door handle and using a finger push the plastic piece forward from the back.

So after I got a jump from the Hyundai Auto car service, the Stop / Start at a light function would no longer work. I was told by a battery dealer that jumping an AGM battery will destroy about 10% of its function. The Dealer had to replace the battery to get my Stop / Start function to work again. I went and bought myself a Noco 10 amp battery charger and randomly do full charges on the battery since I drive less then 10 miles normally when I go out. So far no more issues with the battery and have owned SUV for 1 year now.
 
#7 ·
I had the exact same thing happen to me about 30 days after I bought my 2020 Santa FE Sel. Parked the SUV over the weekend and on Monday morning battery was completely dead. There is a trick to getting the plastic piece out so that you can use the key. You have to pull on the door handle and using a finger push the plastic piece forward from the back.

So after I got a jump from the Hyundai Auto car service, the Stop / Start at a light function would no longer work. I was told by a battery dealer that jumping an AGM battery will destroy about 10% of its function. The Dealer had to replace the battery to get my Stop / Start function to work again. I went and bought myself a Noco 10 amp battery charger and randomly do full charges on the battery since I drive less then 10 miles normally when I go out. So far no more issues with the battery and have owned SUV for 1 year now.
Thats super interesting, I havent had any issues with stop start of course since my car is constantly turning on and off the engine to enter hybrid and ev mode. Ill use that door handle trick you mentioned the next time I get a completely dead battery, because following the manual for removing the plastic cover of the mechanical key slot definitely did not work. Ill be sure to ask my dealership at my next service if there is something defective with my cover! Fortunately, my car jumps itself with the traction battery, so hopefully, hyundai designed it to not hurt itself when being jumped, but who knows as this is the first generation of a new hybrid platform and im honestly just getting ready for so many more issues to pop up. Ill be a happy customer as long as they keep helping me without charging me.
 
#8 ·
i have a 2020 sonata hybrid and am having battery issues...the 1st time it happened was on a mon mrng when the car sat idle since fri afternoon..no power at all..hyandai emgcy got AAA to come and jump car..i took car to hyandai..they said they found no issues after they had it for 3 days...a wk later the same thing..no power...i had car towed to another dealer and they explained how to use the 12v reset and they had another identical car in for the same issues...after a wk they still dont know why....a wk qtr again no power..this time the i used the 12v reset as instructed and the car started but they still have no idea why this is happening...so frustrated...have 35k miles and live in fl and drive 60 miles 5times a wk...help...
 
#9 ·
I use my vehicle in a short driving spurt sense normally, only 3 to 5 miles per use typically as I do errands at college; however, I went hiking one weekend like I might normally (a 22 mile drive back to my parking location at night) where I then locked up my vehicle and had no notification from my app of any systems still being on to drain the battery. I came back to my vehicle which had been sitting outdoors with no tree cover above it over 4 days (meaning the solar roof should have charged the traction and accessory battery to full over that period of time) and neither my key fob nor my phone worked for unlocking or communicating with the car. It was dead enough to not have the security light flashing on the dashboard. Ended up calling roadside assistance where we attempted to remove the plastic cover on the door handle to reveal the mechanical key hole. Even while following the owners manual, the plastic cover would not come off. Even wedged a knife in the gap and it would not budge. The roadside assistance even said that it should be easy to take off which it never did come off (will talk to dealer about that at next service). Eventually had to wedge and pump the door open and open using a handle wire. As soon as I got into the car, I pressed the 12volt to traction battery self jump button and the car started up like it normally would if it needed a self jump. It has been a few weeks and I haven't had the same issue, so I have no idea if I will randomly have that happen again. The solar roof should in theory, prevent that from ever happening, so it was very disappointing to have that happen with no explanation from Hyundai Customer Care at the time. Wondering if anyone has the same issues. Reference info: Car was purchased July 31st, 2020 Had less than 1k miles on it at the time of the incident one other time I remember the solar panel not being on in the past when the car was parked outside for 5 hours. Even if the solar panel wasn't on, a car battery shouldn't die in 4 days, especially this new. (could be related to the new technology of the 12volt lithium ion accessory battery and its implementation. Weather was mild Cloud cover was very limited
I am literally dealing with the same problem with my 2022 Sonata hybrid (with solar panels). My car was idle for 10 days. Parked outside in the sun. I’m waiting to be towed and not sure how they are going to open my door to put in neutral. I hope Hyndai can address this problem.
 
#10 ·
I have had the same problem. Sat at the airport for 15 days out in the open. Expected the solar panel to keep it charged but it didn't. Left my 2022 tuson hybrid partked in the garage and it started up with no problem and it sat a longer time. Took the Sonata because of the solar roof charging, next time I will use the Tuson. BTW was able to start the car with the battery reset but it is a pain to remove the lock cover so I could use the key to get in.
 
#11 · (Edited)
I have a 2021 Limited Hybrid, and I have had the same issue twice recently. The first time was about a month ago. The solar panel had been getting plenty of light. I drive my car pretty much every day, so it doesn't sit idle, either. I also had the same problem as you getting the cover for the manual keyhole off. I even watched Hyundai's video first, and it didn't work. I guess broke it because I can't get the cover to stay on now. Really, really sh*tty design.

Then it happened to me again a few days ago. Pushing the 12V reset button fixed the problem both times. I have had the car since new - about 18 months and 15K miles ago - never had the problem until a month ago.

I did have a warning that appeared about 2 months ago that referred to something in the Hybrid system - code P1B7600, BMS (battery management system). The dash message I got indicated that I should take the car in immediately, according to owner's manual. Of course, Hyundai service didn't know the meaning of that and tried to schedule me a month out. After several calls and getting disconnected after long holds, I pushed the 12V button and restarted the car and that error went away. Maybe this is related, I don't know...
 
#12 ·
I have a 2021 Limited Hybrid, and I have had the same issue twice recently. The first time was about a month ago. The solar panel had been getting plenty of light. I drive my car pretty much every day, so it doesn't sit idle, either. I also had the same problem as you getting the cover for the manual keyhole off. I even watched Hyundai's video first, and it didn't work. I guess broke it because I can't get the cover to stay on now. Really, really sh*tty design. Then it happened to me again a few days ago. Pushing the 12V reset button fixed the problem both times. I have had the car since new - about 18 months and 15K miles ago - never had the problem until a month ago. I did have a warning that appeared about 2 months ago that referred to something in the Hybrid system - code P1B7600, BMS (battery management system). The dash message I got indicated that I should take the car in immediately, according to owner's manual. Of course, Hyundai service didn't know the meaning of that and tried to schedule me a month out. After several calls and getting disconnected after long holds, I pushed the 12V button and restarted the car and that error went away. Maybe this is related, I don't know...
Do you have a separate disable system installed in your vehicle that was installed at the dealership? Jonathan
 
#14 ·
I spoke to my service manager, and they actually had a limited sonata with the same issue, and they took it in and had to diagnose it, which took a month working with the factory. The issue turned out to be the BMS (Battery Management System). They replaced the BMS and 12-volt battery to resolve the issue.
 
#15 ·
That's what I was afraid of. I did get a BMS error code a few weeks before the dead car issue started. I gave that code to my service department when I took the car in, they didn't seem to think it was any help. I haven't had the problem since the day I took it in, and it's been about a month.
 
#16 · (Edited)
I am having a similar issue with my 2020 Hybrid Limited (with solar panels). It was parked all day in the sun, but this morning is completely dead. I didn't have time to manually unlock the door to try the reset because I had to get a kid to school, but will try later. This is very frustrating since there have been no indicators of any problem.

(added) OK, I went back home and used the physical key to open the door. I hit the "12V reset" button and the theft alarm went crazy. It took half a minute to get the car to start by pushing the start/stop button with the key fob. But, it worked and everything seems ok. The only downside is that it reset my MPG count and I was at 59 MPG.
 
#17 ·
I am having a similar issue with my 2020 Hybrid Limited (with solar panels). It was parked all day in the sun, but this morning is completely dead. I didn't have time to manually unlock the door to try the reset because I had to get a kid to school, but will try later. This is very frustrating since there have been no indicators of any problem.
yes, it's frustrating because there are no error codes, it's frustrating because the manual key keyhole cover is a pain to remove (mine is still missing, so that helps), and it's frustrating because it keeps happening. My problem reappeared a few days after my last post, and its happened 4 or 5 times since. Very random, and sometimes after the car has only been sitting for a couple of hours. I guess I'll have them look at it again on my next oil change, but my local service department seems uninterested with no error code.
 
#20 ·
I think very few people are having this problem, so maybe there's not enough data yet to point to the solar panel having anything to do with causing it.

What's surprising is that it shouldn't happen if the solar panel is keeping the battery charged as it's supposed to. Then again, I've had it happen just a few hours after turning the car off, so keeping the 12V battery charged may not have anything to do with it at all. Maybe something in the system is draining it.

Post #14 in this thread said replacing the BSM and 12V battery solved the problem (after leaving the car at the dealership a month for diagnosis)

But how do we get our Hyundai service departments to do this? What am I going to drive while they work on diagnosing the problem? If I end up keeping the car I'll fight them on it, but I'm leaning towards moving on after the lease is up.
 
#21 ·
I have the exact same problem with my 2020 Sonata hybrid. About 6 months ago the 12 V battery was completely dead after only 2 days left idle. I had to use the manual metal key to open the door and do the battery reset button . It happened again a few months later and since then has become more frequent and now almost weekly.
I noticed it only happens when it is parked outdoors uncovered. Never happens when I park it in a car port or indoor parking lot. So yes it is definitely the Solar panel draining the 12 V battery. I took it to the Dealership and they confirmed this and are now replacing the 12 V battery. Still under warranty.
But I'm not impressed that a 2 yr old car needs a new 12 V battery . Not sure I'd go for Hyundai again.
 
#26 ·
I have the exact same problem with my 2020 Sonata hybrid. About 6 months ago the 12 V battery was completely dead after only 2 days left idle. I had to use the manual metal key to open the door and do the battery reset button . It happened again a few months later and since then has become more frequent and now almost weekly.
I noticed it only happens when it is parked outdoors uncovered. Never happens when I park it in a car port or indoor parking lot. So yes it is definitely the Solar panel draining the 12 V battery. I took it to the Dealership and they confirmed this and are now replacing the 12 V battery. Still under warranty.
But I'm not impressed that a 2 yr old car needs a new 12 V battery . Not sure I'd go for Hyundai again.
2020 Hybrid Sonata limited w/ solar panel and does NOT have a 12V battery. I drive almost daily and it's parked with plenty of sunshine to charge via solar panel. The car was running fine and well maintained. Car is not garaged and it rained very hard with very high wind the previous night. This is the 2nd time in 4 months I've had the same problem of not having any power, FOB didn't work, no dash security light flashing, and Blue Link didn't respond. As if the car was completely dead with no power. I couldn't open the door with FOB so I used mechanical key. I couldn't start, unlock door or get system status via the Blue Link App. Even the red LED dash security light wasn't flashing. This 1st occurred in April 2023 (I reported the problem to Pride Hyundai in Seekonk, MA.) and occurred again on July 30, 2023. Car has 33,200 miles so it's still warrantied until October 2023. Fortunately, both times this occurred at my home. Hyundai Roadside sent AAA. Actually, the same AAA driver arrived. Both times he jumped the car and it started with no visible issues. When started, I immediately checked the lithium battery gauge and it was 60% charged which seemed odd it wasn't fully charged after sitting in the sun much of the day. Other than this issue the car runs fine. I'm thinking it also rained the night before the 1st time this problem occurred. Is the solar panel shorting??
Questions:
1. Is there a reset available (again, no 12 V) as opposed to getting the car jumped?
2. Is there a fix for this problem?
3. Is this a common issue with 2020 Sonata Hybrids w/ solar panels with or without a 12V battery?
4. Should there be a Hyundai recall? Very disappointing and frustrating for a car under warranty.
5. Any information or advice would be appreciated. Thanks!!
I've posted a few times about this problem as I have continued to have for a while, including several times in the last 3 weeks. Today was a new experience. I drove the car all day to a couple of places for work, came home, and went grocery shopping about an hour later. No problems all day. I went to one store for about 15 minutes, came out and started the car and drove to another store about 5 minutes away. I was there about 30 minutes. Came out, and my Sonata was completely dead.

I'm due for an oil change in a few weeks, and I'm going to ask the dealer to look at this again. I don't think this is as simple as a battery draining issue. I think there is a problem with the BMS - maybe it's just the solar panel cars, maybe not, but I don't think the panel itself is draining power that quickly, especially since it is designed and constructed to provide power, not use power. This happened on a very cloudy, rainy day, so sunlight / roof panel charging certainly didn't play a part.
 
#22 ·
Same issue with my 2021 Hyundai Sonata Hybrid Limited (Solar Panel). Currently have 45,250 miles on it. Took it to the dealer and they mentioned they have another car with a similar problem. They replaced the Power Relay Assembly and tested it out with no problems. Once I got the car and drove to work a couple days later it happened again, my guess is they didn't diagnose it and just assumed that was the issue but yeah I'm not sure what's going on. Im going to disconnect my nexar dashcam for a week and see if thats causing a parasitic drain but other then that if that doesn't work I'll go ahead and see what the dealership has to say and go with what thread #14 mentioned on the Battery Management System and new 12V battery.
 
#23 ·
I've posted a few times about this problem as I have continued to have for a while, including several times in the last 3 weeks. Today was a new experience. I drove the car all day to a couple of places for work, came home, and went grocery shopping about an hour later. No problems all day. I went to one store for about 15 minutes, came out and started the car and drove to another store about 5 minutes away. I was there about 30 minutes. Came out, and my Sonata was completely dead.

I'm due for an oil change in a few weeks, and I'm going to ask the dealer to look at this again. I don't think this is as simple as a battery draining issue. I think there is a problem with the BMS - maybe it's just the solar panel cars, maybe not, but I don't think the panel itself is draining power that quickly, especially since it is designed and constructed to provide power, not use power. This happened on a very cloudy, rainy day, so sunlight / roof panel charging certainly didn't play a part.
 
#25 ·
I have a 2020 Hybrid Sonata limited w/ solar panel and does NOT have a 12V battery. I drive almost daily and it's parked with plenty of sunshine to charge via solar panel. The car was running fine and well maintained. Car is not garaged and it rained very hard with very high wind the previous night. This is the 2nd time in 4 months I've had the same problem of not having any power, FOB didn't work, no security light flashing, and Blue Link didn't respond. As if the car was completely dead with no power. I couldn't open the door with FOB so I used mechanical key. I couldn't start, unlock door or get system status via the Blue Link App. Even the red LED dash security light wasn't flashing. This 1st occurred in April 2023 (I reported the problem to Pride Hyundai in Seekonk, MA.) and occurred again on July 30, 2023. Car has 33,200 miles so it's still warrantied until October 2023. Fortunately, both times this occurred at my home. Hyundai Roadside sent AAA. Actually, the same AAA driver arrived. Both times he jumped the car and it started with no visible issues. When started, I immediately checked the lithium battery gauge and it was 60% charged which seemed odd it wasn't fully charged after sitting in the sun much of the day. Other than this issue the car runs fine. I'm thinking it also rained the night before the 1st time this problem occurred. Is the rain causing the solar panel to short?? Just a thought. Very frustrating.
Questions:
1. Is there a reset available (again, no 12 V) as opposed to getting the car jumped?
2. Is there a fix for this problem?
3. Is this a common issue with 2020 Sonata Hybrids w/ solar panels with or without a 12V battery?
4. Should there be a Hyundai recall? Very disappointing and frustrating for a car under warranty.
5. Any information or advice would be appreciated. Thanks!!
 
#24 ·
2020 Hybrid Sonata limited w/ solar panel and does NOT have a 12V battery. I drive almost daily and it's parked with plenty of sunshine to charge via solar panel. The car was running fine and well maintained. Car is not garaged and it rained very hard with very high wind the previous night. This is the 2nd time in 4 months I've had the same problem of not having any power, FOB didn't work, no security light flashing, and Blue Link didn't respond. As if the car was completely dead with no power. I couldn't open the door with FOB so I used mechanical key. I couldn't start, unlock door or get system status via the Blue Link App. Even the red LED dash security light wasn't flashing. This 1st occurred in April 2023 (I reported the problem to Pride Hyundai in Seekonk, MA.) and occurred again on July 30, 2023. Car has 33,200 miles so it's still warrantied until October 2023. Fortunately, both times this occurred at my home. Hyundai Roadside sent AAA. Actually, the same AAA driver arrived. Both times he jumped the car and it started with no visible issues. When started, I immediately checked the lithium battery gauge and it was 60% charged which seemed odd it wasn't fully charged after sitting in the sun much of the day. Other than this issue the car runs fine. I'm thinking it also rained the night before the 1st time this problem occurred. Is the solar panel shorting??
Questions:
1. Is there a reset available (again, no 12 V) as opposed to getting the car jumped?
2. Is there a fix for this problem?
3. Is this a common issue with 2020 Sonata Hybrids w/ solar panels with or without a 12V battery?
4. Should there be a Hyundai recall? Very disappointing and frustrating for a car under warranty.
5. Any information or advice would be appreciated. Thanks!!
 
#30 ·
I think very few people are having this problem, so maybe there's not enough data yet to point to the solar panel having anything to do with causing it. What's surprising is that it shouldn't happen if the solar panel is keeping the battery charged as it's supposed to. Then again, I've had it happen just a few hours after turning the car off, so keeping the 12V battery charged may not have anything to do with it at all. Maybe something in the system is draining it. Post #14 in this thread said replacing the BSM and 12V battery solved the problem (after leaving the car at the dealership a month for diagnosis) But how do we get our Hyundai service departments to do this? What am I going to drive while they work on diagnosing the problem? If I end up keeping the car I'll fight them on it, but I'm leaning towards moving on after the lease is up.
Ok.
 
#33 ·
My 2020 Sonata Limited Hybrid was one of the first cars to be diagnosed with this problem, the dealership had never seen this issue and kept my vehicle for over 90 days dealing with the corporate techs trying to figure it out. As stated previously the problem is the accessory/auxiliary battery and the BMS and also a power relay. Since mine happen they have supposedly issued a bulletin to let dealership techs know to check out these 3 items when the symptoms many of you are describing come into their shop.
 
#35 ·
My 2020 Sonata Limited Hybrid was one of the first cars to be diagnosed with this problem, the dealership had never seen this issue and kept my vehicle for over 90 days dealing with the corporate techs trying to figure it out. As stated previously the problem is the accessory/auxiliary battery and the BMS and also a power relay. Since mine happen they have supposedly issued a bulletin to let dealership techs know to check out these 3 items when the symptoms many of you are describing come into their shop.
I have been having the issue and i have had it die while driving. I really hope they have this advisory.
 
#36 ·
So, after about a year and 3 attempts, my problem is finally fixed. The part replaced was the "Solar DC Converter Unit Assy".

This time, my service guy said, "what we do with these cars now is call Hyundai university and work with them on the problem". I wish they had done that the first two times. They also had to replace the cover for the manual door lock on the driver's door handle. This took me 2 appointments, and then they had it painted the wrong color white. 3 days after getting the car, it fell off when I touched the door handle.

I have to give this car up in May when my lease it up, and it's killing me. I LOVE this car but won't be able to buy it. The only positive thing about it is that I won't have to deal with the service department anymore.
 
#37 ·
So, after about a year and 3 attempts, my problem is finally fixed. The part replaced was the "Solar DC Converter Unit Assy".

This time, my service guy said, "what we do with these cars now is call Hyundai university and work with them on the problem". I wish they had done that the first two times. They also had to replace the cover for the manual door lock on the driver's door handle. This took me 2 appointments, and then they had it painted the wrong color white. 3 days after getting the car, it fell off when I touched the door handle.

I have to give this car up in May when my lease it up, and it's killing me. I LOVE this car but won't be able to buy it. The only positive thing about it is that I won't have to deal with the service department anymore.
Hello There,

I am having the same problem with my 2020 Hyundai Sonata Hybrid. It is happening more often now like 5 to six days a part. Started it this year in august. My question to you is how long o go did they fix your car at and are you problem free since? Where are you located at and what is your Hyundai servie phone number? I would like to talk with them because they are familiar with the problem. My biggest problem is that I moved from the US to Budapest Hungary my car is from the US and Hyundai is not making this model for EU market. Therefore, they have no software that can reed my cars computer. Please help me out.
Looking forward to hearing from you.
Thanks
Frank
 
#39 ·
I have the exact same problem. I dropped off the car to the Kearny Mesa Hyundai 4 times but they kept saying "the car is operating as designed". They cannot find the issue.
They blame the dash cam and alarm but it doesn't make sense to me. Because they are sitting there since 3 years.
Do you guys have any updates about this issue?
 
#40 ·
I had a hard time with my dealer, too. One time, they tried to blame my wireless android auto dongle and also did an ECU update on my car that wasn't even the correct update for the motor in the Hybrid. Apparently, no error code appears, so they don't know what else to do.

Tell them that Hyundai is aware of this problem, and they should check the Solar DC Converter. Maybe print a few pages out from this forum to show them. If they give you the same BS, ask them (or demand) that they call Hyundai.
 
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