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Regenerative braking, do the brake lights turn on?

PoitNarf

My dog's breath smells like dog food
Jun 7, 2016
2,870
4,008
NJ
I know that this is a stupid question, but do the brake lights turn on during regenerative braking? I’m completely new to EVs and have my Model 3 set to the standard setting for regen. It’s stronger than I was expecting so I’m hoping that the driver behind me does get some visual queue that I’m doing some kind of braking, especially when the regen drops the speed pretty quickly.
 
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PoitNarf

My dog's breath smells like dog food
Jun 7, 2016
2,870
4,008
NJ
Yes, they do. You can see the lights in the diagram of the car on the screen when they light up.

I’ll have to look for that on my next drive. Had no idea they lit up on the graphical Model 3 on the screen!
 

Skidmark

Member
Oct 16, 2017
310
317
San Jose, CA
Here's what it looks like on my car - it could be a lot harder to see if your car is red.
brakelights.jpg
 

novox77

1.21 Gigawatts
Nov 25, 2017
1,640
3,550
NH, MA
I know that this is a stupid question, but do the brake lights turn on during regenerative braking?

This was one of my questions when I did my first test drive of an S last summer. The Tesla rep said it was a good question! Even though he's probably had to answer it a million times. I do look at the screen for confirmation still, mainly to see when they kick in. On some long slight uphills, you can come to near stop (no regen) and never have the brake light come on.

Full release of the pedals almost always triggers brake light. Exception is at highway speeds. Regen is maxed out so you don't decelerate as quickly. Plus it's not good for traffic flow when brake lights come on on the highway, cause it can trigger a wave of people braking - the makings of a traffic jam.
 

Skidmark

Member
Oct 16, 2017
310
317
San Jose, CA
Exception is at highway speeds. Regen is maxed out so you don't decelerate as quickly. Plus it's not good for traffic flow when brake lights come on on the highway, cause it can trigger a wave of people braking - the makings of a traffic jam.

It does come on at freeway speeds. I've followed behind plenty of S drivers that don't know how to control their accelerator foot and always try to drive around them if possible.
 
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novox77

1.21 Gigawatts
Nov 25, 2017
1,640
3,550
NH, MA
It does come on at freeway speeds. I've followed behind plenty of S drivers that don't know how to control their accelerator foot and always try to drive around them if possible.

I wonder if there's a difference between S and D, since regen is stronger with the D. I have just the rear motor. I'll be going 70mph and let go of the accelerator completely and my brake light won't come on till around 55mph or so.
 

ℬête Noire

Active Member
Jan 30, 2018
3,105
2,556
TX
I wonder if there's a difference between S and D, since regen is stronger with the D. I have just the rear motor. I'll be going 70mph and let go of the accelerator completely and my brake light won't come on till around 55mph or so.
Probably. I've seen it as a complaint (at least at one time?) about D's as well at much higher speeds, that in the 80+mph range their brake lights won't come on when they take their foot full-off the accelerator. So there's different regen algorithms for different variants, leading to different brake light behavior.
 

RyanS

Ka-chow
Sep 9, 2017
287
421
Elk Grove, Republic of California
You can see it at night time with back up camera on. With MS, it is very clear when light comes on. M3, it is kind of hard to see, especially on a brightly lit road. Test it on some dark road. With MS, actual light and graphical model light didn’t always match.
 

Skidmark

Member
Oct 16, 2017
310
317
San Jose, CA
I wonder if there's a difference between S and D, since regen is stronger with the D. I have just the rear motor. I'll be going 70mph and let go of the accelerator completely and my brake light won't come on till around 55mph or so.

I just tested on my Model 3....let off the accelerator at 80 and saw the brake lights activate on the graphical representation of the car at 77mph.
 

PoitNarf

My dog's breath smells like dog food
Jun 7, 2016
2,870
4,008
NJ
Yeah I actually paid attention to this on my drive into work this morning. Works just as I would expect it to.
 
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Bad Horse

Member
Aug 10, 2017
162
108
Overland Park
I literally was thinking about this question this morning, glad there is a topic. My worry was more thinking about my drive back up to the KC area this last Sunday in the terrible icy/snowy weather, and wondering if I had regen on, and I slowed down, how would a car behind me know I was slowing down? In that weather especially, it's more than just fender benders that can happen. Good to know now.

BTW, as I get closer to placing my order, there are more things like this I think about depending on the driving circumstances.
 

PoitNarf

My dog's breath smells like dog food
Jun 7, 2016
2,870
4,008
NJ
I literally was thinking about this question this morning, glad there is a topic. My worry was more thinking about my drive back up to the KC area this last Sunday in the terrible icy/snowy weather, and wondering if I had regen on, and I slowed down, how would a car behind me know I was slowing down? In that weather especially, it's more than just fender benders that can happen. Good to know now.

BTW, as I get closer to placing my order, there are more things like this I think about depending on the driving circumstances.

I think I've read from others that in snow/ice conditions you should turn regen off completely.
 

Skidmark

Member
Oct 16, 2017
310
317
San Jose, CA
I think I've read from others that in snow/ice conditions you should turn regen off completely.

Agreed - if you will be driving in icy conditions, you should set the regen to low (I don't think you can turn it off completely).

Interesting observation - I was cornering reasonably hard this morning while lifting off the accelerator and regen seemed to shut off completely. I'm very familiar with weight transfer while braking and cornering and how this can lead to oversteer, but this was a bit disconcerting because I had to use the brakes a lot more than I was expecting to.
 

PoitNarf

My dog's breath smells like dog food
Jun 7, 2016
2,870
4,008
NJ
And I don't disagree with that, but my worry is more having to remember.

Yeah, definitely going to have to remember that myself. There was an unexpected snow storm in NJ yesterday so I had to drive to work in the snow. I never even thought about altering the regen setting. It would be great if the Model 3 kept track of the current weather in your area and would make the suggestion about changing regen temporarily.
 

ahkim

Member
Feb 20, 2018
94
124
Minnesota
I think I've read from others that in snow/ice conditions you should turn regen off completely.

My take after a first drive in icy/snowy conditions is the regen is a major safety issue, especially for less experienced snow drivers or people unaware of how regen works. I did a few 40mph "coasts" and the rear of the car broke loose until the stability control (SC) kicked in. There's too much of a delay for SC to kick in, it probably will keep the car stable 90% of the time, but I'm more worried about what might happen at higher speeds. So I agree that regen should be turned down, but I wish there was a way to disable in icy conditions. I'll be posting some videos later today from my drive.
 

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