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Discussion Starter #1
Greetings

Bought a 13 or so Elantra during that ridiculous cash for clunkers program where I got $4000 for a $200 Chevy. Not a bad car at all. Got me thinking about the company. Bought wife a '16 Soul a couple years ago. Cheap and she loves it.

Always been interested in EV's and hybrids. Daughter has a Leaf. I drive often too far for a pure EV so hybrid it is. The plug in is a bonus for local stuff..

Out the door for $28k and change. With $4500 tax credit, cheap for what it is.

I have a host of questions. The most burning is how to tell where regeneration braking turns to friction braking.

Looking forward to perusing the forum and the owner's manual.
 

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Above 30mph, you can watch the charging meter, and when you hit the brakes hard enough for the meter to drop to "max charging" (the lowest point on the meter), then if you brake any harder it will start adding friction braking. But it doesn't switch from one to the other, the friction brakes only supplement the regenerative braking when they're needed for additional stopping force.

Below 30mph, it gets less obvious because the meter will never hit "max charging" no matter how hard you hit the brakes. So what I do, is slowly add pressure to the brake pedal and watch the charging meter, and once I hit the point where applying more brake pressure isn't causing the meter to show any increase in charging, I keep the brake pedal where it's at.
 

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That's a good explanation, glocked. I've owned my Niro Phev for a few months now and still don't understand the charge meter when slowing down. I own a Pacifica PHEV, and the regen charge meter is very 1:1 with braking, and very accurate at all speeds. In other words, if I slow at 50mph or 25 mph, it will show a very realtime regen amount on the meter, and even the slightest changes to the brake pedal will be reflected in the regen meter immediately. However, with the Niro, it's like it's kind of lazy. Like it's just guessing. If I barely push the brake at 50mph, it'll jump down to max regen, but then if I do the exact same thing as I slow, it'll only go to, say 75%. If I push down on the brake harder, it doesn't regen any more than 75%. It doesn't correlate with changing brake pedal movements. I wonder if it's intentional to allow better traction by involving the rear brake pads more readily, or who knows. But I gotta say, it's a bit annoying when compared to my Pacifica.
 

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Physical brakes never kick in for me until the final couple feet of a full stop. But I usually am slowing down well ahead of a full stop and seldom stop briskly. Even a fairly brisk stop does not engage them. At highway speeds, never (outside of a panic incident). Regen provides a lot of deceleration, and at least in theory, the PHEV provides more.
 

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Discussion Starter #5
Excellent, great advice in watching the meter for it ceasing an increase with additional brake.

Does the brake light light ever with smart cruise regen slowing or just when it uses friction brakes? I wish they'd just give us a wee light when the friction brakes activate.

Also, has anyone figured out a good way to pre heat the car on charge to avoid IC engine starting purely for heat? My LX doesn't have eather an inverter or a hot 12v outlet.
 

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Excellent, great advice in watching the meter for it ceasing an increase with additional brake.

Does the brake light light ever with smart cruise regen slowing or just when it uses friction brakes? I wish they'd just give us a wee light when the friction brakes activate.

Also, has anyone figured out a good way to pre heat the car on charge to avoid IC engine starting purely for heat? My LX doesn't have eather an inverter or a hot 12v outlet.

Yes, the rear brake light does illuminate whenever the friction OR regen brakes are active, including when the car does it automatically during cruise control. Pretty sure it's legally required to light the brake lights any time the car is actively slowing itself down (whether it be through regen braking or friction braking, or automatically or manually).


Good question on the pre-heating... I never really thought about using a space heater to pre-heat the car, but that's an interesting idea. Curious what others here think. For power, you could install your own 12V "always on" outlet, someone here was talking about how to do that in another thread some time ago. Be aware that it uses the 12v lead-acid battery, though, which means a portable heater will drain it fairly quickly, and cause the car to automatically disconnect the battery to avoid it getting completely drained. I doubt you can connect a portable heater directly to the HEV battery, nor would I think the Kia warranty department would be keen on that idea.


Maybe run an extension cord out to your car, through a cracked window?
 

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Discussion Starter #7
Isn't there a provision for the traction battery to charge the lead acid?

Sorry if I'm a bit behind in reviewing the owner's manual.

As far as the brake lights during regen; there must be some threshold. My wife on the phone in a car behind me said they never came on as I forced a good bit of regen braking approaching a slower truck in smart cruise. YMMV
 

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Isn't there a provision for the traction battery to charge the lead acid?

Sorry if I'm a bit behind in reviewing the owner's manual.

As far as the brake lights during regen; there must be some threshold. My wife on the phone in a car behind me said they never came on as I forced a good bit of regen braking approaching a slower truck in smart cruise. YMMV

Yes - there are (slightly different) mechanisms in the PHEV and the HEV for charging the 12V battery from the traction battery. But I don't think this is a good option for preheating the car. A few years ago, I was going to a pot-luck dinner and I looked into the idea of plugging a crockpot into an inverter plugged into my cigarette lighter so that I could keep my contribution warm on the way to the dinner. After all, the crockpot only draws about 150 watts (less than an old 3-way incandescent lightbulb), which is way less than an electric space heater (typically those run around 1500 watts). But the cigarette lighter was rated for a max of 10 amps at 12 volts: e.g. 120 watts, and that's before any parasitic losses from running the inverter to convert DC into AC. I've seen what can happen to a wiring harness if you overload the cigarette lighter circuit and you're unfortunate enough to not have a fuse blow: it isn't pretty, and it's very expensive.


As for the brake lights, this is a really interesting question that I've been wondering about too. If you've had someone following you and telling you via phone when your brake lights come on, my bet is that you know more about the Niro behavior in this regard than most anyone else here.

I recall reading about a lawsuit many years ago where someone was going up a hill, took their foot off the accelerator to slow down and avoid cross traffic, and the guy behind them plowed into their rear end and then sued because they slowed down without ever signaling. I don't recall who won the suit, almost think it was the guy who hit them. But whether he won or not, just the fact that you could even be sued over something like this is food for thought.

When driving a conventional car, we can slow down by taking our foot off of the accelerator and also by shifting into a lower gear and using engine braking. Neither one of those actions will turn on the brake lights. When driving a car with regenerative braking, what we're really doing is something very similar to engine braking, in that the electric motor which normally propels the car is being used to slow the car down by generating electricity to recharge the battery. Until the brake pads actually make contact with the rotors/drums, there might not be an actual legal requirement for the car to turn on the brake lights: at least, the manufacturer might not be required to make that happen, but we as drivers might be required to signal to traffic behind us, regardless (and any such requirement might vary from the laws of one state/country to another).

However, there is at least one electrical switch that is triggered by moving the brake pedal, and in most cars, that switch does at least two things, even at the lightest touch of the pedal: it turns on the brake light and it disengages the cruise control. In the Niro, I believe that there is a second switch/mechanism that first switches on regenerative braking and then eventually engages the hydraulic brakes if you push the pedal far enough, hard enough. So I'd be very surprised if putting my foot lightly on the brake pedal was not turning on the brake lights at the same time that it was disengaging cruise control and engaging regen braking.

But when driving with smart cruise control where the car is actively slowing down by engaging regenerative braking, I've often wondered if the brake lights come on or not.. Perhaps they aren't legally required to from the manufacturer's perspective, because it's technically just "engine braking".
 

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Not sure if there are legal requirements yet for regen to light up brake lights, but for Ioniqs/Niros with regen paddles, you definitely don't get brake lights on the first level of regen. Nor does my Niro HEV (no paddles) light up brakes when I take my foot off the accelerator. I don't think it does with light "braking" either, but I'm not positive. I would like to know, but I've not had anyone follow me yet or jury rig a mirror on my back window yet.
 

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Update to my prior post: This evening I noticed that when driving after dark, the brake light casts a dim red glow on the rear wiper arm that is visible in the rear view mirror (at least,it's visible if you don't have someone tailgating with their high beams on). But! This idea is kind of in the "don't try this at home" category. Driving around in the dark and looking at your rear view mirror when you have a legitimate reason to slow down because of something in front of you isn't exactly the safest/smartest thing to be doing. With that said, what I observed during a very brief drive this evening is that the Niro's brake light behavior seems to be exactly like I would hope and consistent with my experience in conventionally powered cars.


Coasting down hill with my foot off the pedals, I observed a mild charge indication on the dashboard and a sensation of gradual slowing, consistent with engine braking in a conventional car, and as I would have hoped/expected/anticipated, there was no brake light.


But with a light tap on the brakes, there was both a mild charge indication on the dash and a brake light glow visible in the rear view mirror.


With Smart Cruise Control enabled and actively decelerating more quickly than would happen with just coasting (because the car in front of me was slowing down) the brake lights came on and were visible in the rear view.


These observations reflect about 10 minutes of driving under a very narrow range of conditions. If you observe something that contradicts the idea that the Niro brake lights behave like a comparable but conventional ICE powered car, I think many forum readers would be interested to hear about that.
 

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Update to my prior post: This evening I noticed that when driving after dark, the brake light casts a dim red glow on the rear wiper arm that is visible in the rear view mirror (at least,it's visible if you don't have someone tailgating with their high beams on). But! This idea is kind of in the "don't try this at home" category. Driving around in the dark and looking at your rear view mirror when you have a legitimate reason to slow down because of something in front of you isn't exactly the safest/smartest thing to be doing. With that said, what I observed during a very brief drive this evening is that the Niro's brake light behavior seems to be exactly like I would hope and consistent with my experience in conventionally powered cars.


Coasting down hill with my foot off the pedals, I observed a mild charge indication on the dashboard and a sensation of gradual slowing, consistent with engine braking in a conventional car, and as I would have hoped/expected/anticipated, there was no brake light.


But with a light tap on the brakes, there was both a mild charge indication on the dash and a brake light glow visible in the rear view mirror.


With Smart Cruise Control enabled and actively decelerating more quickly than would happen with just coasting (because the car in front of me was slowing down) the brake lights came on and were visible in the rear view.


These observations reflect about 10 minutes of driving under a very narrow range of conditions. If you observe something that contradicts the idea that the Niro brake lights behave like a comparable but conventional ICE powered car, I think many forum readers would be interested to hear about that.

Those are exactly my observations, too.


Mild regeneration while coasting (say, 20% of the "charging" meter?), but no brake light. Tap the brake ever-so-slightly, and the "charging" meter drops further, and brake lights come on.


I think people who say the brake lights don't come on while using regenerative braking are confusing it with what I'd call "regenerative coasting", which isn't really braking.
 

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I think people who say the brake lights don't come on while using regenerative braking are confusing it with what I'd call "regenerative coasting", which isn't really braking.
Yep, I think it's pretty simple when you are driving normally, no cruise control:

Coasting, foot off the gas, not on the brakes = no brake lights
Any pressure at all on the brake pedal even if you are not decelerating more than you would be just coasting = brake lights

I do wonder about how it works with the smart cruise control though. It's not clear to me that there the car ever just coasts as opposed to actively braking. Obviously, when the car is actively decelerating the brake lights are on, but does the car ever just coast? I doubt it just based on how smart cruise controls work. They are actively trying to maintain the desired speed so in general they are always doing one of three things, applying steady power to maintain speed, accelerating to reach the desired speed, or braking to maintain the desired speed. I know there is some "fuzzy" logic built in and you can set how aggressively the car tries to maintain speed, but in the end, it's always doing something.

Interestingly, if you disabled the smart part of the smart cruise control, then the car probably does coast when the speed is above the set point, at least that's how it works on older dumb cruise controls that don't have brake authority. :nerd:
 

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Discussion Starter #13 (Edited)
I'm quite sure that max regen braking is no more than an agressive downshift in a conventional car... legal with no brake lights. I'm also sure that even a touch on the brakes does light the lights. On most cars, the switch is on the pedal itself but it could be on the master cylinder as well.

Max regen braking has to be less than 60 hp, really not that much. Smart cruise always is accompanied by autonomous braking.

From all these posts, the few tests I've done and the logic above, I think with at least some degree of certainty that the brake lights only illuminate when the friction brakes are in use, pedal or as autonomous braking is used by smart cruise.
 

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I do wonder about how it works with the smart cruise control though.

Hi, Its pretty simple.. you cruise at 55mph, with the second choice of space (lets say. 100 feet..) between you and the car in front.. if he is going at 52mph, you will slow down at 52mph.. if he goes faster than 55mph, (60mph) you will accelerate at 55mph, not more.. if he slow's again at 45mph, you will drop at 45.. if he makes a full stop, you will too.!



simple as that.! i have tested it at 15mph with a friends car in front. kind of like this... made for genesis and shared on hyundai and kia..

 

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Hi, Its pretty simple.. you cruise at 55mph, with the second choice of space (lets say. 100 feet..) between you and the car in front.. if he is going at 52mph, you will slow down at 52mph.. if he goes faster than 55mph, (60mph) you will accelerate at 55mph, not more.. if he slow's again at 45mph, you will drop at 45.. if he makes a full stop, you will too.!
Yeah, I got that part, except for the full stop, the smart cruise in the Niro cuts out at 6mph. My question was whether the car ever just coasts under smart cruise control as opposed to actively braking.
 

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Yeah, I got that part, except for the full stop, the smart cruise in the Niro cuts out at 6mph. My question was whether the car ever just coasts under smart cruise control as opposed to actively braking.
It doesn't intentionally coast, but it does briefly sometimes when neither braking nor acceleration are needed. I would guess it coasts about 0.01% of the time, versus 99.99% braking or accelerating. To be fair, the conventional cruise control doesn't really coast much either. Cars without active cruise control braking coast a lot in cruise control, because it's the only way to slow the car on a downhill, but most modern cars use the brakes instead of coasting.
 

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It doesn't intentionally coast, but it does briefly sometimes when neither braking nor acceleration are needed. I would guess it coasts about 0.01% of the time, versus 99.99% braking or accelerating. To be fair, the conventional cruise control doesn't really coast much either. Cars without active cruise control braking coast a lot in cruise control, because it's the only way to slow the car on a downhill, but most modern cars use the brakes instead of coasting.
Yeah, that's kind of what I figured. I've used the smart cruise in the Niro quite a bit and it's not bad, but it does tend to be more aggressive in keeping the speed at the setpoint than I would prefer even though I have it set to the slowest response. In particular I wish it wouldn't downshift so much on mild inclines. I've noticed that when I drive manually I can keep the car from downshifting and still maintain approximately the same speed on a shallow hill where the SCC will downshift.

Oh well. Nitpickers gonna pick nits. :D
 

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Discussion Starter #18
Did a little test with my daughter following me today and watching brake lights. At all moderate speeds, the brake lights came on at the first notch in the blue regeneration area regardless of what caused it.... brake pedal or smart cruise. This is a good approximation of the normal car threshold between engine and friction braking. I was surprised that brake pedal didn't light the brake lights until that threshold was reached but, I suppose it makes sense.
 
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