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Hi everyone. I am new to this form and found it as I was trying to troubleshoot my system.
I noticed that my ISG doesn’t come on anymore unless I charge my battery over night, then it works for a few days and stops again.
I had my battery tested twice now, once at the dealer and it registered 73% SOC and had it done weeks later at autozone and it registered 76% SOC. Is that normal ?
if that battery hovers at that range all the time, then the ISG will rarely come on.
Dealer doesn’t really want to replace the battery because it’s “technically” testing GOOD.
Any thoughts?
Per the Repair Manual/Owner Manual: Battery State of Charge (SOC) less then 68% will prevent the ISG from engaging. Of course, there are may other conditions which must be met. If you mostly drive short distances, it is likely the battery is not getting fully charged. Many newer vehicles do not "constantly" charge the battery like older vehicles - instead they charge only as necessary to keep the vehicle operational (and startable) as this can help gas mileage (not constantly charging sheds some load on the engine and can save a bit of gas). I suspect Hyundai probably utilizes the "load shedding" as most on the forum never see a full state of charge on their battery. My guess is that a new battery would probably improve the battery SOC and allow ISG to engage more often.

Personally, I'd be happy if ISG never engaged on mine (I've permanently defaulted mine to OFF) but I understand those who do like the feature. I suspect it will be a challenge to get the dealer to replace the battery. So, a couple of options are: 1. replace the battery at your cost (probably $150ish). You could get a battery (make sure it is an AGM battery) from many places that will be much cheaper than the dealer, 2. make a deal with the dealer, replace the battery and if it solves it, the dealer pays for the battery, if not, you pay the dealer for the battery, 3. put a battery tender on it once a week or every night, 4. Live with it the way it is. I'm sure there are many other options too. Based on what you describe, I would guess you usually drive short distances and the battery is probably marginal (even though it tests OK). Anyway, those are my thoughts..... Let us know what you decide to do and how it turns out.
 

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You are correct! I don’t drive for very long. I drive exactly 9.6 miles each way to work and back, 50% at 65MPH and the other 50% at 40MPH.
I would think that roughly 10miles/17 min should keep a car charged pretty well.

But I do agree with you, some people hate the system, some love it. I personally have had 3 leased cars with it prior to this Santa Fe. All other car’s IGS systems worked flawlessly for the 3 year leases. I feel like even though the system has been on Hyundai’s for many years now (European market), it’s like an after thought here in the USA and they didn’t implement it very well.

Since my testing shows that every time I charge my battery and drive off, the ISG works flawlessly, I do believe that the SOC is the only condition I am not satisfying for when it stops working.

Additionally, I did just went out to my car that’s been sitting in the garage (68deg) for about 5 hours and took an open circuit measurement of the battery, it registered 12.49V. If that were a healthy battery, I would anticipate a higher voltage.

Any battery experts in this forum that can share some knowledge, do you think I should just get a new battery?
 

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2020 2.4 SEL FWD
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Hi everyone. I am new to this form and found it as I was trying to troubleshoot my system.
I noticed that my ISG doesn’t come on anymore unless I charge my battery over night, then it works for a few days and stops again.
I had my battery tested twice now, once at the dealer and it registered 73% SOC and had it done weeks later at autozone and it registered 76% SOC. Is that normal ?
if that battery hovers at that range all the time, then the ISG will rarely come on.
Dealer doesn’t really want to replace the battery because it’s “technically” testing GOOD.
Any thoughts?
I took delivery of a 2020 Santa Fe SEL a month ago and have added 416 miles on top of the 59 demo/dealer miles. My major usage of the car is average 50 mile trips with a few stops each trip. Just about all miles are on country roads at 50-70 mph, no traffic and very few stop signs.

The ISG worked very well in the beginning but quickly became erratic so I started keeping notes on ISG function two weeks ago and started recording battery charge one week ago. Erratic like not having ISG until parking back at home at the end of a 60 mile trip with one 4 hour stop in the middle. And another 46 mile trip with two quick stops and 4 town miles when the ISG never worked at all. And then on other days, having a functional ISG system after 5 miles or less.

What I've learned since tracking voltage is after 48 hours of shut down (with no electrical usage) following 52 miles of driving in the previous two days, the battery was down to 12.34v just prior to a IGS test drive. That drive required somewhere between 34.7 and 35.9 miles before the battery was full enough for ISG to show signs of life. An hour after completing this run of 47 miles, the battery was 12.71v.

Then, 92 hours later, the next 50.1 mile drive to town began with voltage of 12.47. ISG functioned on the first attempt after leaving our driveway. 4.5 miles away. Go figure?

So, I don't know anything yet other than I wish it would sort itself out before dealer time. Maybe the battery has a percentage problem or the "Smart Charging" isn't all that intelligent and having a difficult time learning my driving habits. I'm putting a full charge and /test on it tonight (with a proper fully automatic AGM charger) so maybe something can get retrained and it will work better. I like the ISG but it don't do me much good if it doesn't work until I get back home. It's really nice when it is working because I've learned how to feather the brake and turn it off before parking but it's great for traffic lights in town.
 

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2019 Santa Fe Ultimate 2.0T HTRAC
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Battery charge is only one of the many variables for ISG to work.
 

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2020 2.4 SEL FWD
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I know the requirements. I RTFM and the comprehensive list posted in this very same thread and just about every ISG thread in the forum. I can't honestly visualize any non-compliant scenarios that would cause this behavior besides voltage.
 

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I know the requirements. I RTFM and the comprehensive list posted in this very same thread and just about every ISG thread in the forum. I can't honestly visualize any non-compliant scenarios that would cause this behavior besides voltage.
Did you capture outside temperature, engine temperature, and accessory load (a/c, heated seats, heated wheel, fan speed, lights, and infotainment? The ISG in my 2019 SF is like clockwork and will typically work within 5 mins after engine gets to temp.
 

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‘19 Santa Fe Ultimate 2.0T FWD (Machine Gray/Espresso Gray)
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Hi everyone. I am new to this form and found it as I was trying to troubleshoot my system.
I noticed that my ISG doesn’t come on anymore unless I charge my battery over night, then it works for a few days and stops again.
I had my battery tested twice now, once at the dealer and it registered 73% SOC and had it done weeks later at autozone and it registered 76% SOC. Is that normal ?
if that battery hovers at that range all the time, then the ISG will rarely come on.
Dealer doesn’t really want to replace the battery because it’s “technically” testing GOOD.
Any thoughts?
Hyundai seems engaged in a cover-up to prevent owners from easily knowing the level of their battery charge. The battery charge used to be shown on the Bluelink App, but it was removed mid-2019. My guess is that more and more owners were trying to find out why the ISG was no longer working on their vehicles.

Last month I had my dealer check the non-operating ISG on my Santa Fe. They got it operating again and then had the nerve to tell me that I wasn’t driving it enough to charge the battery sufficiently. Okay, most of my daily trips are local, but I do put 8,000 miles per year on the car. For gawdsakes, Hyundai, change the specs on the ISG activation requirements. Drop the battery charge limitation to 60%. Do what needs to be done!
 

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Yes, the ISG is really very smooth and “seamless” is a good description.
For comparison, my fun car is a MINI Cooper (2015) and their version of ISG is basically not driveable in stop and go traffic. Fortunately they issued firmware change that remembers if you’ve disabled the feature when you shut off the car and I have never used it since then. I still do a lot of stop and go driving in traffic and the SF system is relatively unobtrusive. There have been a few times I’ve disabled it but the ability to ease off the brake pedal and restart the engine without moving helps a lot. I do this frequently when I’m going to have to make a turn into traffic and accelerate quickly.
 

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Gateswood,

Lately, I put my battery on an automatic AGM charger twice a week and the ISG system works fine. The question then becomes, is it a battery issue or a smart charger issue ?

Note, Yesterday it worked while the temp outside was reading 28F on the car.

Also, I assume that the voltages you are reading are when you disconnect the terminals. I noticed that the car has some parasitic drain when the battery is connected, so the readings are incorrect when connected to the car.

I think that when it's summer time, I am going to replace the battery and see how that works. I wonder if the ISG system is damaging the battery because it's not designed well?

SnailFE,

I had a 2012 BMW 328Xi and a 2016 MB C450, both with ISG and they worked great till the day their leases ended.
 

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2020 2.4 SEL FWD
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Did you capture outside temperature, engine temperature, and accessory load (a/c, heated seats, heated wheel, fan speed, lights, and infotainment? The ISG in my 2019 SF is like clockwork and will typically work within 5 mins after engine gets to temp.
Thanks for the info but most of the features you mention have not been required or used. The weather is consistently in the 50's and 60's these days so there's no need for heat, a/c, defrost or heated seats although I have tested all of them. I did drive 30 miles in the rain one day so I used the wipers and the headlights came on. I typically don't listen the radio and use my phone as normal with my bluetooth headset so the infotainment system is largely unused.

The charger completed it's charge and test routine after a tad more than 12 hours and is now in float mode. Ideally, the battery should now be charged to full capacity. Hopefully, this will make a difference if the smart charging or an improperly trained battery is an issue. It would be nice to know if any particular voltage equates to the Hyundai battery sensor >68% SOC requirement for proper ISG function.



Gateswood,

Lately, I put my battery on an automatic AGM charger twice a week and the ISG system works fine. The question then becomes, is it a battery issue or a smart charger issue ?

Note, Yesterday it worked while the temp outside was reading 28F on the car.

Also, I assume that the voltages you are reading are when you disconnect the terminals. I noticed that the car has some parasitic drain when the battery is connected, so the readings are incorrect when connected to the car.

I think that when it's summer time, I am going to replace the battery and see how that works. I wonder if the ISG system is damaging the battery because it's not designed well?
I don't have the link but there are references in the forum about how the Hyundai charging systerm gets goofed up and won't fully charge the battery no matter how you drive. I guess it's all about the computer quest to save every drop of fuel. I'm hoping this problem can be simply solved since the car is so new. If not, I'm just collecting data for the dealer.
 

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Thanks for the info but most of the features you mention have not been required or used. The weather is consistently in the 50's and 60's these days so there's no need for heat, a/c, defrost or heated seats although I have tested all of them. I did drive 30 miles in the rain one day so I used the wipers and the headlights came on. I typically don't listen the radio and use my phone as normal with my bluetooth headset so the infotainment system is largely unused.

The charger completed it's charge and test routine after a tad more than 12 hours and is now in float mode. Ideally, the battery should now be charged to full capacity. Hopefully, this will make a difference if the smart charging or an improperly trained battery is an issue. It would be nice to know if any particular voltage equates to the Hyundai battery sensor >68% SOC requirement for proper ISG function.





I don't have the link but there are references in the forum about how the Hyundai charging systerm gets goofed up and won't fully charge the battery no matter how you drive. I guess it's all about the computer quest to save every drop of fuel. I'm hoping this problem can be simply solved since the car is so new. If not, I'm just collecting data for the dealer.
honestly, the dealer doesn’t give a crap. They hate people like us who tell them what they found. They think of you and I as someone who “knows more than them”.

I gave them my car to look at for they issue, they kept it parked all day in the same spot, even tho they said they were working on it. Even bluelink showed that they didn’t move it.
If it’s a smart charge issue, then it’s a Hyundai problem that the dealer can’t fix. If it’s a battery issue, then I am the one who has to figure it out, not them.
 

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I don't have the link but there are references in the forum about how the Hyundai charging systerm gets goofed up and won't fully charge the battery no matter how you drive. I guess it's all about the computer quest to save every drop of fuel. I'm hoping this problem can be simply solved since the car is so new. If not, I'm just collecting data for the dealer.
Out of curiosity, what AGM charger do you have, and do you have to disconnect rest of the car while charging it?

For what it's worth, I've had pretty similar experience with my battery/ISG too. I bought a Santa Fe Ultimate 2.4 FWD in April, and ISG worked very consistently until around the time the weather cooled off here (October-ish? Texas) and now has only triggered a couple times since then, one time was after ~3 hours of driving it straight. I did change my driving habits around the time the weather was cooling, previously was driving on the highway ~40-60 minutes each day but now I'm doing that only a couple times a week + ~40 minutes of slower 30-45mph street commutes.

Initially I was concerned the battery was pre-maturely failing, and I was checking the battery voltage every night and in the morning. I didn't disconnect the power straps, so some parasitic load is included, but I've seen between ~12.15V all the way up to 12.7V, without any pattern. At idle the voltage is around what I'd expect the alternator to put out (mid 14V or so).

I stopped by dealer a couple months back and had the battery checked, its CCA were fine and they didn't have any more insight in what to check without paying the diagnostic fee. I do know that their proprietary OBD2 reader can pull out battery SOC and battery "health", from some of the literature online, but they haven't provided that info.

The Santa Fe has continued to crack pretty quickly, so I'm unsure at this point whether it is an issue with the battery, the smart alternator, or operating as designed. I did find an obscure reference at ISG & Battery from a German Kia FAQ that the ISG is suppose to operate in a carbon neutral fashion, where the 'nominal' SOC is lower, below the ISG activation threshold, and "extra" energy gained through engine breaking (coasting, downhill), brings the SOC above the ISG threshold so that it will then activate carbon neutrally. If it instead always charged the battery above the ISG threshold, then ISG would be a net fuel loss instead of fuel gain. Whether this is still valid for the Santa Fe's ISG, I'm not sure, but it sounds plausible that some combination of continuous A/C usage (overall higher load so alternator also stayed engaged, thus charging the battery?) and more highway driving (coasting/downhill) could have kept the SOC above the threshold, but in the cooler months and with my shorter drives it is now settling at a lower SOC as designed. Hopefully the return of the summer months will answer this question. Until then, I keep an Anker lithium jump start battery in the trunk just in case.
 

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2020 2.4 SEL FWD
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I have a Swedish CTEK MUS 4.3 charger. No need to disconnect anything. In fact, it comes with perma-leads that can be installed to the battery so the charger can simply be plugged in to the car.

Thanks for the info and the link. The old info by ThomasDK does make sense in a perverted sort of way. Since that was more than five years ago you would think Kia and Hyundai would have it figured out by now. But maybe they do. If so, you would think they'd be more forthcoming about all these little carbon neutral idiosyncrasies of the system.

I think my car may have some wicked IOD loads that vary from day to day. I guess a lot of it may have to do with staying in communication with the "mother ship" I know mine phones home after every drive and obviously lays there waiting for bluelink or Mama Hyundai to send a signal.

I'll have to check with my brother to see what sort of fancyass computer equipment he has at his shop for getting into the brains of a Hyundai. Maybe he can run me a full dx report. I was hoping for more from my first bluelinked Monthly Vehicle Health Report but that was a joke. Almost insulting to think I anxiously awaited that thing for a month.

What bothers me about my new car is it does things that simply aren't logical. And what bothers me about your new car is you have to carry a jump starter to feel secure. That's so wrong. I have one of those but I don't even carry it in a 20 year old car with an 8 year old battery that I only drive a couple times a month.
 

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What bothers me about my new car is it does things that simply aren't logical. And what bothers me about your new car is you have to carry a jump starter to feel secure. That's so wrong. I have one of those but I don't even carry it in a 20 year old car with an 8 year old battery that I only drive a couple times a month.
Your scenario is a head scratcher with no real loads and ISG still not activating? Does your dash show the ISG as inactive? For reference I had my first oil change today and leaving the dealer the ISG activated at the stop sign leaving the parking lot! It was about 50 degrees and I didn’t have any accessories on.

Regarding some of these other issues. Testing battery voltage every night and charging every other day? This is self inflicted. Drop the car off at the dealer until they fix it! Start with a new battery, alternator, and keep going until the issue is resolved. Get the dealer to provide a loaner or rental.
 

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Your scenario is a head scratcher with no real loads and ISG still not activating? Does your dash show the ISG as inactive? For reference I had my first oil change today and leaving the dealer the ISG activated at the stop sign leaving the parking lot! It was about 50 degrees and I didn’t have any accessories on.

Regarding some of these other issues. Testing battery voltage every night and charging every other day? This is self inflicted. Drop the car off at the dealer until they fix it! Start with a new battery, alternator, and keep going until the issue is resolved. Get the dealer to provide a loaner or rental.

You may be getting some messages crossed. I think that was somebody else who was charging regularly. I put a charger on mine one time to bring it up to an alleged 100% and that was Saturday night.

My ISG activates just fine but the confusing part is sometimes it won't activate until the final full stop brake application of a 60 mile drive while at other times it will activate at the end of the my driveway before I pull onto the road. Miles logged in previous days seem to have no bearing on which way this will go.

It will certainly go to the dealer 30 miles away at some time but with only 522 miles on the car, I won't be taking it there any time soon and definitely not until more things are sorted out. Right now the priority is learning the car and giving other things time to goof up a little or a lot.
 

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Your scenario is a head scratcher with no real loads and ISG still not activating? Does your dash show the ISG as inactive? For reference I had my first oil change today and leaving the dealer the ISG activated at the stop sign leaving the parking lot! It was about 50 degrees and I didn’t have any accessories on.

Regarding some of these other issues. Testing battery voltage every night and charging every other day? This is self inflicted. Drop the car off at the dealer until they fix it! Start with a new battery, alternator, and keep going until the issue is resolved. Get the dealer to provide a loaner or rental.
TAGSF19U,

Sometimes, the answer to your problems are not simple. Car systems are complex, and to truly identify an issue, you need to go through a systematic approach to isolate the problem. A dealership model is setup to make money, such an approach is not in their best interest as it is not profitable. Also, a certified technician is simply a person who knows how to use the tools given to them by the manufacturer, they aren’t a person who can really dwell into a system and understand it inside out.

that being said, all I am doing by measuring voltage and placing the battery on a charger is understanding the underlying issue. By understanding the issue, I can determine a solution (if one exists). Armed with my test results, I can present a case to the dealer and hyundai to make the necessary repairs/changes.... if you didn’t gather this already, I am an engineer, and I try to follow an engineering approach to solutions.

last time the dealer looked at my car, they did validate that my battery SOH was not where it should be for a new car. The problem was that the battery could start the car so in Hyundai’s eyes, the battery is perfectly fine. On top of that, the dealer had removed parts from my car and forgot to reinstall them. So I am sorry that I don’t really praise the dealership for being all knowing!
 

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What bothers me about my new car is it does things that simply aren't logical. And what bothers me about your new car is you have to carry a jump starter to feel secure. That's so wrong. I have one of those but I don't even carry it in a 20 year old car with an 8 year old battery that I only drive a couple times a month.
Agreed that I do think it's more of a communication/transparency issue, where it's not clear what the expected behavior is. I'd probably be carrying around the battery jumper pack anyway, since it's useful if a friend needs a jump too. The car hasn't in any way failed (always starting up within a second or two), so the discomfort is with expecting more traditional behavior (e.g. the-battery-should-be-fully-charged-in-30-minutes-of-driving and that ISG should always activate in all normal day-to-day conditions).

Purely speculation, but it could well be that an always-activating ISG is net fuel savings on average across all drivers, but for certain driving patterns (lots of short trips) the car spends more fuel charging the battery than it saves turning off the idling engine. So, instead perhaps Hyundai/Kia configured ISG threshold and alternator to not excessively waste fuel charging the battery only to have it used for ISG, hence only charging the battery to 100% SOC when fuel isn't being used to do so. That would be pretty clever if true (again, speculation based on that German Kia paraphrase), and AGM batteries would probably support that deeper discharge much better than conventional lead-acid, but without communication it's not possible to tell if it's a bug or a clever feature.
 

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2019 Santa Fe Ultimate, 2.4L
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Here's a possible data point that I haven't seen mentioned in connection with the ISG failures. The ISG in our 2019 Santa Fe Ultimate 2.4 worked flawlessly and frequently until the Service Campaign 953 was applied on December 13th (last month)--it hasn't activated a single time since that date. I took it to the dealer this morning and they failed to find anything wrong with it, although they admitted that they couldn't get it to turn the engine off. It was apparent the service manager knew much less about the ISG system than I did (from reading the owners manual). He said to drive it and bring it back if it doesn't start working again.

I don't believe in coincidence--I think something happened during the SB953 software update (i.e. left it in diagnostic mode etc.). When I mentioned that, the SM asked me what diagnostic mode was. . .SMH! Has anyone else noticed the ISG fail after the software update?
 
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