regen--brake lights

regen--brake lights

When the model 3 slows down by regen braking, do the brake lights come on to warn following cars you're slowing down?

Pg3ibew | January 16, 2020


FISHEV | January 16, 2020

It will show the brake lights on the car graphic but the graphic is so small and the light indicator so faint you can't really tell. You can even really see the lights in the image but if you look real close you see a rose blush on the white background.

Subaru kept a viewable graphic of the car up showing brake lights, doors, lane keeping etc. Tesla could look at how Subaru or other good example does it. Should be easy fix.

Be better if Tesla had an easily viewable graphic of the car on the screen showing brake lights, headlights, turn signals etc. Could even use it for the common equipment failure alerts such as "Camera not working".

FISHEV | January 16, 2020

"You can even really see the lights in the image" = "You CAN'T see the lights in the graphic"

Joshan | January 16, 2020

OP yes they do.

just ignore the idiot who likes to stare at a GUI while driving to see if his brake lights are on instead of looking at the road like normal people.

Joshan | January 16, 2020

Tesla doesn;t need to "fix" anything to be more like the car maker who has the most at fault accidents on their cars.

Bighorn | January 16, 2020

Yes | January 16, 2020

I was curious about this as well, so I tested it on a private road, and the graphic DOES show the lights coming on when using regen, so I assume the lights are coming on as well.

gparrot | January 16, 2020

I’m another idiot who looks at the GUI for information. And FISHEV is right, there is only a faint blush difficult to distinguish. Good luck seeing anything at all at night, on the dark GUI.
And I too would like to see this information more obvious, à la Subaru.

Bighorn | January 16, 2020

Do you worry about when or if your brake pedal engages the brake lights? Or was downshifting a manual car fraught knowing there were no brake lights? The accelerometer has worked fine for a decade.

Joshan | January 16, 2020

On your last car how did you verify the brake lights were coming on? Why do people feel the need to micromanage every aspect of the car? The car handles most everything for you, let it.

M-A-B-MCMLXXX | January 16, 2020

No need to assume. Go out and drive at night. Once you hit the threshold deceleration (per statute) you’ll see your lights in the rear view mirror.

CharleyBC | January 16, 2020

I think it's a fair question. If it's one's first car with significant regen, you could reasonably wonder whether the brake lights being tied in is a feature. Years of ICE experience give one confidence that the brake lights are connected to the brake pedal. But regen is something new to many. That is, the question isn't really, "is it working or broken?" It's more like, "is it a feature?"

Answer: yes.

Joshan | January 16, 2020

ya my comments were to the fish idiocy not the OP, it was a valid question.

Frank99 | January 16, 2020

You can pinch-zoom the car on the display until you can see the third brake light just below the rear window. My understanding is that it’s a lot easier to see on white cars than on red cars like mine.

andy.connor.e | January 17, 2020

The easiest way to know if your brake light is on. Is regen on? If yes, is there a deceleration force acting on the car? If yes, brake lights are on. Assume they are on if you are decelerating with regen.

andy.connor.e | January 17, 2020

Regen is your new brake peddle. Enjoy not wearing down your brake pads.

AWDTesla | January 17, 2020

How many of you survived in your old cars, blows my mind.

andy.connor.e | January 17, 2020

Hard to believe anyone made it this far eh?

AWDTesla | January 17, 2020

andy.connor.e | January 17, 2020
Regen is your new brake peddle. Enjoy not wearing down your brake pads.

Just make sure you service them often. Min is twice a year. I do mine 4 times a year since we have so much salt, sand, and the fact I track the car. You should hear the brake pads brake from the rotors when sitting overnight. It actually sounds like a broke something.

andy.connor.e | January 17, 2020

Yep, i live in the northeast lots of salt. Pretty much everyone in my family has one or two of their pads rust every now and then. Very difficult to avoid it. Maybe Tesla should make brake pads out of the 30x cold rolled stainless steel!

AWDTesla | January 17, 2020

Oh, and this is all covered in your owners manual.

Regenerative Braking
Whenever Model 3 is moving and your foot is
off the accelerator, regenerative braking slows
down Model 3 and feeds any surplus energy
back to the Battery.
By anticipating your stops and reducing or
removing pressure from the accelerator pedal
to slow down, you can take advantage of
regenerative braking to increase driving range.
Of course, this is no substitute for regular
braking when needed for safety.
Note: If regenerative braking is aggressively
slowing Model 3 (such as when your foot is
completely off the accelerator pedal at
highway speeds), the brake lights turn on to
alert others that you are slowing down.
Note: Installing winter tires with aggressive
compound and tread design may result in
temporarily-reduced regenerative braking
power. However, your vehicle is designed to
recalibrate itself to restore regenerative
braking power after a short period of normal

dsp | January 17, 2020

Also, something to keep in mind is when you pass someone, allow time and space to clear the car before you let off your accelerator. I have heard that Tesla's are getting a bad reputation for "cutting people off and brake checking them." For us, it's passing a car and letting off the pedal, but to others, because the brakes lights do come on, it looks like an ass move.

Bighorn | January 17, 2020

Easy to do with a quick acceleration to pass.

Frank99 | January 17, 2020

dsp -
That's precisely why I occasionally monitor the brake lights. I know that, because of ...mumble, mumble... years of driving ICE cars with automatics, I have a bad habit of pulling my foot off the accelerator anytime I want to stop accelerating or when I want to cover the brake or for whatever. No big deal on an ICE - someone following me would simply see a slight deceleration - but on the EV I'm sure my brake lights flash a LOT in comparison. I know I'd hate to follow me.
I try to pay attention to exactly what level of deceleration corresponds to brake lights, so that they communicate effectively with the driver behind me.

andy.connor.e | January 17, 2020

It will get better over time as more people become accustomed to how EVs work.

TabascoGuy | January 17, 2020

...or people will learn how drive better. Passing someone and then decelerating once you're in front of them is an ass move. In any car.

mt917 | January 17, 2020

In my experience once you lift on the accelerator the brake lights come on. I think this is over cautious and very annoying to anyone behind me.
In my ICE car I rarely used this brake pedal, I coasted as much as possible. EV's have no coast. It's either go or slow. There needs to be a lot of regen before the brake lights come on. They even came on the other day when I had zero regen going down a hill because it was so cold outside.

gparrot | January 17, 2020

When I see the distance between my car and the car ahead of me slowly diminish, with no braking involved, I pay attention to said car ahead of me. But if I see those brake lights come on, then I do more than just pay attention, I become pro-active: do I have to slam the brakes to maintain a fair distance? Is there someone behind me who could ram me? Do I have space on either side to use to my advantage? I am downright squirrelly.
The brakes are a way to communicate with the car behind me, and I don’t want to scare the bejesus out of him.
Call me an idiot for wanting to monitor my car.

bryan.whitton | January 17, 2020

Gee guys, there is a simple test. While driving at night simply turn on the rear camera and take your foot off the accelerator. The screen turns bright red. That light on coming from the brake lights.

rehutton777 | January 17, 2020

@TobascoGuy: "...or people will learn how drive better. Passing someone and then decelerating once you're in front of them is an ass move. In any car."

Wait a minute. I have been in many situations where, when you pass a car doing, say 60 MPH and you finish your pass at 70 MPH (or higher if there is approaching traffic), it is only logical that you are going to slow down to your normal desired speed. I would agree that if you decelerate to a speed lower than what the car you passed is going - - you are indeed an ass. But you will very likely have to decelerate once the pass is completed in any event.

andy.connor.e | January 17, 2020

You can decelerate without braking or activating regen. Ease up on the accelerator just a little.

majassow | January 17, 2020

And I submit, that after the pass: when returning to 61MPH, as long as you didn't move over at an unsafe distance, and you are traveling faster than the person you passed, who cares if brake lights appear.

If you moved over at an unsafe following distance (for the passed car), and/or drop your speed slower than the car you passed, then it makes you an ass regardless if your brake lights illuminate.

In other words: drive politely and let the brake lights do what they do: tell the car behind you that you are braking (yes: high enough regen is indistinguishable to physical braking for the traffic around you).

Kirbster | January 17, 2020

Coming from years of manual cars I would like to know if the brake lights are coming on or not based on regen.
In a manual of i downshift I know there will be no brake lights. If I brake I will. Since that isn’t possible in an electric car a visual indication would be nice.

Similar thought on passing an braking. In an ICE car if I pass on a two lane road with a 65mph speed limit I might crack 75 before I’m back in my lane in a Tesla I’ll be north of 100 so I’m definitely lifting off the accelerator but I don’t want the driver who is now well in the rear view getting brake lights thinking I’m an ass who just passed them and is now braking.
Not a huge thing but a nice to have.

M-A-B-MCMLXXX | January 17, 2020

^^ our new cars gives other drivers more info than old manual cars. In the tesla the brake light will come on when you press the brake, or when the regenerative braking system trips an acceleration threshold. If you can feel it, the lights are likely on. If you can’t they probably aren’t. You can see on your display if they are.

jordanrichard | January 17, 2020

When the amount of re-gen is equal to or greater than your speed, the lights come on. I have a pre-AP MS with the original speedometer/energy meter where things are larger and easier to read. If I am going 35 mph and if the regen is higher than 35 kw, the lights come on and stay on until the re-gen dips below your speed, as you slow down.

M-A-B-MCMLXXX | January 17, 2020

^that may be a good rule of thumb, but I don’t think they’re using it as the logic. It’s based on negative acceleration.

US code is silent on the matter, but since Tesla sells cars in the EU they probably adhere to EU regulation:

Electric regenerative braking systems as defined in paragraph 2.17., which produce a retarding force upon release of the accelerator control, shall generate the signal mentioned above according to the following provisions:

Vehicle decelerations

Signal generation

≤ 0.7 m/s²

The signal shall not be generated

> 0.7 m/s² and ≤ 1.3 m/s²

The signal may be generated

> 1.3 m/s²

The signal shall be generated

What they do with the *may* would take experimentation to determine.

ODWms | January 17, 2020

I agree the brake light graphic could be more visually detectable, and the threshold for regen trigger of the brake lights could probably be relaxed. Safety concerns being what they are, I get why Tesla has decided to err on the side of caution with the threshold. But I also get why people are concerned about looking like they're going around brake checking other drivers.

M-A-B-MCMLXXX | January 17, 2020

“ But I also get why people are concerned about looking like they're going around brake checking other drivers.”

I don’t. If they’re getting in front of and slowing enough to trigger the lights, the driver below them has every right to know about it. Not once in my life have I been worried that a driver behind me saw my brake lights, but I have in several occasions been concerned that they might not see them.

rehutton777 | January 17, 2020

I think the bigger concern is not inadvertently "brake-checking" other drivers, but slowing down rapidly due to regen braking and NOT having the lights come on leading to you getting rear-ended. This was my major concern early on - - I really was not even aware of the potential "brake-checking" issue. After many months of driving, I am pretty comfortable regarding both concerns now.

FISHEV | January 18, 2020

Driving to SC this AM. Got two hard brakes on I5 from some error in TACC and three "Camera offline" (raining) in 10 miles.

FISHEV | January 18, 2020

On the Regen brake lights. Tesla builds the graphic to show it and then makes it so small no one can see it.

M-A-B-MCMLXXX | January 18, 2020

It’s even harder to see the starlight twinkles it renders on the roof at night. Those displays are equally important, so they really missed the mark with the stars.

jmccpa | January 18, 2020

If you use your fingers to zoom the car icon, you not only can see the brake lights but also the rear turn signal flashing. Unfortunately the zoom image goes back to the original size in a few seconds.

Mauler | January 18, 2020

I had an experience shortly after getting my M3 with my daughter who was following me home. Once we reached home, she asked why I was "on the brakes" so much. To which I replied I had barely touched the brake pedal except to actually stop. That was when I first realized the regen was triggering the brakes lights. :-)

hienkle | January 19, 2020

I understand that when it is cold, i.e. below freezing, re-gen becomes unavailable. This happens to me today (1/19/220) in Maryland where the temperature overnight were 26F and well below 32F in the morning. From noon onward today the temperature rose to 46F but I still haven't gotten re-gen back. Is is a problem? (Car is a M3 DM AWD, delivered just 3 weeks ago).

Bighorn | January 19, 2020

No. Regen is limited up to about 60 degrees, which is the battery not the ambient temperature.