I think this happens in other modes too, including auto regen mode - but honestly, these people who rely purely on brake lights to know to slow down are a liability imo, personally I've sat behind Tesla's and other EVs that are clearly slowing down and no brake lights and it's never caused me an issue or any annoyance. I wonder if these accidents are also in part due to people driving too close behind another car that happens to be slowing down.

Yes, maybe the algorithm needs to be tweaked (I believe the deceleration if hits a certain gforce will trigger the lights) but also people need to pay attention to cars in front of them and not rely on brake lights so much.
With my previous ICE cars I often used engine braking to slow down and brake lights wouldn't have shown (sometimes with significant deceleration) and I never had any issues.

 

2022 US Limited RWD owner here.

This is one of the main reasons I usually keep my regen at Level 1 and use the brake pedal for decelerating, which always turns on the brake lights. IIRC, the brake pedal will use regen to slow down if the regen is set to anything but Level 0. Of course, if you press the brake pedal hard enough (wanting to slow down faster than the regen can) it'll use the brake pads. So setting regen to Level 1 and using the brake pedal gives you the best of both worlds: brake lights to alert the people behind you, and regen braking to charge the battery and save on brake pad use.

 

Over here I've been using auto regen level 3 for about a year, the only thing I do though which maybe makes a difference is if I need to slow down considerably I pull the left paddle for brief maximum regen and from what I've seen, the paddle always seems to trigger her brake lights.
I used to use i-pedal but stopped because actually it seemed to be less efficient than auto regen.

Regardless, I've never had any adverse reaction from a driver behind me when decelerating in this mode with my foot at least partially on the accelerator - or maybe I just haven't noticed it yet 😆

At the same time I do agree though that Hyundai's configuration for when the brake lights doesn't seem very good and could do with tweaking. That said I have a feeling this is probably similar with other manufacturers too.

 

This is not the problem....vehicles with manual transmission do the same thing..... if someone is following too close it his responsibility to react not only by watching brake lights but also observing how much distance is between.

 

Yeah, but only if you set regen level to simulate manual transmission (ie, level 1). Regen levels greater than level 1 do not. Unless you are simulating changing down from 4th to second gear when you meant to change to third.

And I admire the trust you place in other drivers to stop when they can’t see brake lights. Drivers in your country are obviously far better than in mine.

 

Our Y brake lights on regen and I think the Leaf does too.

I do think it's important one pedal driving does this.

 

While driving at night with auto-regen, I've noticed brake lights activate at what equates to about regen 2.

I think this is fine.

I've seen and driven ICE cars capable of stronger engine braking than this.

 

Brake light is active when deceleration threshold is reached...irrelevant to the regen number.

 

The theory here is sound but that is where it ends.

I came to work this morning and it was pitch black out so I could see my hatch brake light. If I lift off the pedal all together in i-pedal mode, my brake lights come on and the vehicle stops mildly aggressively but still not as aggressively as when I actually brake. And this was his findings in the video.

Where I disagree is what point the light engages as you let the pedal out - and how much brake forces are being apply before the brake light comes on.

My foot was probably 80% out of the pedal when the brake lights turn on, if I push the pedal down just a slight bit more to where the brake light just barely is not on and hold it there i.e. "max breaking with no brake lights", sorry it's not braking any harder than when I downshift a manual trans on my old Mustang v8 to slow my speed.

Honestly at the point right before the brake lights turn on in i-pedal mode my old Mustang slows harder in a downshift. Once the pedal is out far enough to engage the brake lights, or you are completely off the pedal again it's still not as aggressive as me actually braking and at this point my brake lights are on, wonderful.

Overall sound theory but real-world testing for me disproves this being any kind of a danger on the Ioniq 5. I don't know about other cars, but on this car I strongly disagree. I think the manufacture did a fine job on this.

The only way I can get items to move around in the cabin from i-pedal is if im deep in the throttle and let off the throttle pedal all the way instantly, but again my lights turn on when i do that.

I urge everyone to drive at night, look at your hatch taillight. Let out your pedal to the max amount just before the lights engage and hold it CONSTANT there. Feel the braking, it's not much!!!


THEY DO WORK RIGHT, LOL!!

 

…sorry it's not braking any harder than when I downshift a manual trans on my Mustang v8 to slow my speed.

Honestly at the point right before the brake lights turn on in i-pedal mode my Mustang slows harder in a downshift. Once the pedal is out far enough to engage the brake lights, or you are completely off the pedal again it's still not as aggressive as me actually braking and at this point my brake lights are on, wonderful.

Overall sound theory but real-world testing for me disproves this being any kind of a danger on the Ioniq 5. I don't know about other cars, but on this car I strongly disagree. I think the manufacture did a fine job on this.

EXACTLY! This is a lot of hooha about nothing.

 

This can be both dangerous and as he mentions a little into the video, a reason both for fault in accidents and fines from the Police.

EDIT: For those who don't want to see, the quick breakdown. In i-Pedal the break lights don't come on before letting go of the accelerator pedal fully, or the care is at a full stop. With the different regen modes, it also have to fully let go of the accelerator pedal.

The cars behind will not see you breaking much of the time, if you don't use the breakpedal.

This is incorrect, my lights come on before i let off. I have the latest update and just got my car "2022 Ioniq 5 SE". Maybe they fixed it I don't know. But this is not true with my car. Mine come on when i left off the pedal to about 80% "or 20% throttle", and if you hold it at 79% "or 21% throttle" when there is no lights at all the vehicle is not braking that hard. As stated downshifting a gasoline car pulls as hard or harder with no brakes lights turning on.

 

This is an interesting topic raised in the video, specially because there are already 3 posts about it here (I reply in this one, because it seems to have the most 'data' already).
Would be nice to have some real/official info on the intended behavior of the brake lights with using regen to slow down the car ... maybe the behavior is different depending on region or local regulations ?


Thanks for reporting this, you gave me an idea:

It would be great to have some test data from users ... a simple test just to check when the brake lights turn on (I can't test it myself yet, just 2 more months let's hope):

• when driving at night, the brake lights should be visible on the main screen when this is set to rearview camera
• pick a section of a road and your preferred driving speed, and choose a specific point to start the test (like a lamp post or something)
• drive in i-pedal > at the test starting point, completely let go of the pedal > check if brake lights are active (they should)> remember how far you got when the car came at a full stop, this will be your reference distance
• drive the same section again in i-pedal > at the test starting point, don't remove your foot from the pedal, but keep it at let's say 95% > check if brake lights are active (if they were not active at all, then you can stop the test)> now you should reach full stop a little further away than your reference point, but not by much (in case you are much further, you can try to press even less on the pedal)
• as long as the brake lights became active, you could do another test with more pressure on the pedal (95-90-85-80-...)
• if you want to go further in detail, you could check the maximum distance or time (from the starting point to full stop) you have been able to go while you had brake lights turning on ... by knowing the starting speed and the distance/time to full stop, the deceleration value can be calculated.

Let's take the example of the creator of the video:

• Imperial:
  He was driving at 60miles/h and it took 13s to full stop, this means about 0.2g and a deceleration of 7feet/s², resulting in a total distance of about 600-640 feet.
• Metric:
  He was driving at 95km/h and it took 13s to full stop, this means about 0.2g and a deceleration of 2m/s², resulting in a total distance of about 180-190m.
  

Brake light is active when deceleration threshold is reached...irrelevant to the regen number.

Do you know what the deceleration threshold could be ?

 

At the end of the video, some deceleration values are mentioned for the EU, and they also appear here at the end of this article:
The Hyundai Ioniq 5 Needs To Rethink Its Brake Lights Before It Causes An Accident (slashgear.com)

So when taking this deceleration value of 1.3 m/s² (4.27 ft/s²) as brake light threshold, testing becomes more easy:
Drive in i-pedal mode at your preferred speed, slow down to 0, and check your distance or time ...

If slowing down more than 1.3 m/s², the brake light should be active.
The value of 0.7 m/s² (2.30 ft/s²) is also mentioned as a value from where brake lights should not be active anymore.

Would be great if anyone could check this in some real world testing

Metric example:
If you are driving at 70 km/h, and you slow down to 0 in less than 155 m or 15 s, the brake lights should have been ON.
If you are driving at 70 km/h, and you slow down to 0 in more than 280 m or 29 s, the brake lights should have been OFF.

speed	1.3m/s²	1.3m/s²	​	​	0.7m/s²	0.7m/s²
	distance	time	< if less than​	if more than>​	distance	time
90 km/h	250 m	19 s	< brake lights ON​	brake lights OFF >​	460 m	36 s
70 km/h	155 m	15 s	< brake lights ON​	brake lights OFF >​	280 m	29 s
50 km/h	70 m	12 s	< brake lights ON​	brake lights OFF >​	145 m	21 s
30 km/h	30 m	7 s	< brake lights ON​	brake lights OFF >​	55 m	13 s

Imperial example:
If you are driving at 45 mph, and you slow down to 0 in less than 545 ft or 15 s, the brake lights should have been ON.
If you are driving at 45 mph, and you slow down to 0 in more than 980 ft or 30 s, the brake lights should have been OFF.

speed	4.27ft/s²	4.27f/s²	​	​	2.30ft/s²	2.30ft/s²
	distance	time	< if less than​	if more than>​	distance	time
60 mph	950 ft	21 s	< brake lights ON​	brake lights OFF >​	1730 ft	38 s
45 mph	545ft	15 s	< brake lights ON​	brake lights OFF >​	980 ft	30 s
30 mph	250 ft	11 s	< brake lights ON​	brake lights OFF >​	445 ft	20 s
20 mph	115 ft	8 s	< brake lights ON​	brake lights OFF >​	200 ft	14 s

 

Thank you for the table. I haven’t checked the math to see how correct they are (I suspect correct) but one problem I see is that most people have trouble estimating distances that accurately and getting accurate timing would likely need a passenger taking measurements.

A quick check of the app store for my mobile phone shows a number of apps that claim to measure G forces. I suspect that might be easier and while the phone/app may not be instrument grade it is likely to be as accurate as an average person trying to measure deceleration distance and time.

I learned to drive many decades ago on a car with a manual transmission (I still have one) and haven’t yet become comfortable with one pedal driving. So I am watching these threads as a matter of curiosity rather than need: I usually have regen set to 1 (except to control speed on mountain grades where I would down shift my old drum brake equipped car) and use the brake pedal to stop.

 

Something I think is interesting is that our I-5 behaves this way, Our GV60 does not. The Brake lamps illuminate when you decelerate, as the I-5 should do.

 

During the horse wagon days, I wondered how in the world there isn't more wagons piled up because they had no brake lights.

I-padel or not and brake lights or not, I provide enough distance between me and the car in front of me, and I slow down when the car in front of me slows down. You can have a million vehicle regulations/vehicle codes, but in the end it's still the person behind the wheel.

Cars don't drink itself drunk, text while rolling, follow to closely, or change lanes without looking, it's the human behind the wheel that does all that.

 

During the horse wagon days, I wondered how in the world there isn't more wagons piled up because they had no brake lights.

I suspect that horse-and-buggy generally moved at a lot slower rate of speed, and there were two to four additional brains that would aid in not causing an accident. Horses, as it turns out, really dislike pain, and will do what they can to avoid the infliction of such, including avoiding smashing into another buggy or carriage.

Oh, fun fact, the first ICE automobile was invented in 1808 in Switzerland, and brake lights weren't introduced until 1915. But yeah, the argument "Well we didn't need it back then, why do we need it now?" is sure to win the debate. Well played o7

 

Because of this video and related posts, my husband and I just did an experiment: He followed me in one car while I drove our 2023 Ioniq 5 RWD. I left it in Regeneration Level 3, which is the default for this model. We drove about 20 miles in different terrain. We spoke with each other via our cell phones the entire time.

I learned that when I take my foot off the accelerator, all of the brake lights come on. If I decelerate more slowly, the brake lights don't come on. I experimented a lot, mostly without ever touching the brake. The pattern held.

This makes sense to me--the brake lights come on when you slow the car down rapidly, alerting the driver behind you. If you ease into deceleration, the driver behind does not get notified--similar to what might happen if you take your foot off the gas in an ICE or downshift in a manual transmission car.

I don't use one-pedal driving, so I didn't experiment with that mode. I really like Regen Level 3, as it allows you to smoothly control the speed of the car. Based on this experiment, I feel confident that drivers behind me will see my brake lights when I lift my foot off the accelerator. That's when it matters most.

Hope this helps others who got concerned based on this video.

 

No one is saying brake lights are not needed. All we're sayinging is it doesn't take to see brake lights for you to know you need to slow down or stop.

 

It isn't required to see the brake lights for one to notice the lead vehicle's decel, but it does aid in reaction time before you react and hit your own brakes. Some studies suggest up to 500ms slower reaction speed with no lit brake lights, which at 60 mph is about 3 car lengths (47 feet). Doesn't sound like much, until you also factor in the vehicles stopping distance. Example: 2022 Ioniq 5 is rated for a stopping distance of 123 feet or roughly 8 car lengths. No brake light reaction time can thus crank it to 170ft which is about 12.5 car lengths. Those extra car lengths can be the difference between a stopping short, or overrunning into a crunch.

I feel that Dunning-Kruger Protocol is in effect here, so I'll leave it at that

 

It's funny someone mentioned horse and buggy, then was shot down as its old and slow.. Lets talk about F1 or Nascar then. 200mph with 0 brake lights lol. Funny quote I just saw

"Formula 1 does not have brake lights like most other racing organizations, which in tern would make the drivers loose focus. But during wet weather conditions during a race all the cars are built with a flashing red light to warn and let other drivers know where they are when visibility is low. "

Point being lights are just a guideline and in no way make or brake serious car accidents. If a car gets turned into a pancake it has 0 to do with brake lights and 100% to do with user error.

Also again lol... enable i-pedal and hold your pedal at 20% depressed... If you think thats hard braking your nuts... Less then 20% and you might as well be letting off and getting your girly brake lights to turn on 🤣

 

Funny, I was Just thinking about that same thing while driving home and providing plenty of distance between cars. Some people like to play the blame game and never look in the mirror, a little thing called personal responsiblity. Technologies help make you drive safer, but in the end you still control the car. You can't help how others drive, but you have full control on how you drive.

 

If I correctly understand the many posts in this thread, you’re saying it is NOT the keyboard causing me to misspell words? Did I git that rite?

 

If I correctly understand the many posts in t
his thread, you’re saying it is NOT the keyboard causing me to misspell words? Did I git that rite?

Yes, you would be correct. Missing spelling words hasn't cause any car crashes yet. If that's the worst I can do, I can live with that.

 

I agree, mine work fine, wife was filling me and said they work normally both on L3 and I-pedal

 

Some of you are making ridiculous arguments to defend how the brake lights currently work.

Brake lights DO turn on in i-pedal, but only when your foot is fully off the accelerator. If I barely have the accelerator depressed the brake pedals do not turn on, even if I'm very quickly coming to a stop.
This is pretty agressive deceleration, much more than a car with a manual transmission.


Do I need to see the brake lights of the person in front of my to slow down? No. But it certainly helps in some scenarioes.

Do the people behind me need brake lights to know that I'm slowing down? In a perfect world no, but these people are crazy. Too many distractions for people who are either on their phone or day dreaming.

The discussion isn't about what WE need to slow down, we're talking about the distracted driver behind us that has no insurance and doesn't care.

 

Again be in i-pedal mode and hold the accelerator down 20% constant and don't move it, its not braking that hard, the only time it brakes hard is when your at like 5% or totally out of the pedal all together. Hence why you don't see the light till then.

And yes my old v8 mustang slowed just as much downshifting as my cars i-pedal does when im still into the throttle a bit, it felt like you were applying mildly aggressive brakes.

 

Regen 3 works just fine. My wife is an accelerator stabbed. Inside is very jerky and I dreaded how the brake lights worked when we got the I5 until I was driving behind her. There was no appreciable slowing and no brake lights flashing as she let off. Only when she was fully off and the vehicle was slowing. I drive in Gen 3 and very much moderate the throttle coming to a stop and only a short tap of the brake. Never had any notification from other drivers in 9 months

 

Lord have mercy lolol, Again as I have stated, hold the pedal at 20% in i-pedal mode, not much pull, if you go beyond 20% you may as well be letting all the way out. Again its a non-issue in real world use. Honestly even holding the pedal at 10% in i-pedal its still not crazy pull, and again why not just let all the way out of the pedal, it feels natural to let out of the pedal completely at anything under 20%.

I think the whole point of this dudes video is that I-pedal mode and the brake lights are a danger in the real world. And I whole heartedly disagree!!

 

The break light issue is important. Here in the Atlanta area tailgating is a sport, as is red light running, and right-on-red. Break lights are a major defense, and lack of same is an excuse for stupidity. My experience with iPedal and level 3 regeneration is that no break light happens until full release of accelerator. It seems though that cruise control exhibits break lights at deceleration it induces.

 

I guess Hyundai also agreed that it's an issue.

Hyundai to update EV brake lights; our tests show how they currently may not come on - Autoblog

We test Hyundai, Kia and Genesis electric vehicles to test if they can be stopped without the brake lights coming on.

www.autoblog.com

 

I guess Hyundai also agreed that it's an issue.

They pretty much had to do this, for protection from liability issues.