Brake light function with one pedal driving?

[zefram47]

Here is the UN standard, which now that Rivian is going international, they must follow.

UN Regulation No. 13-H Stop Lamp Illumination - UNECE https://unece.org/fileadmin/DAM/trans/doc/2020/wp29grva/GRVA-07-48e.pdf

That's nice, but it's not a US federal requirement and hence no manufacturer uses it for US market vehicles. The video from Technology Connections goes through this in depth.

IMO Rivian should lower the threshold. I can come to a stop with little to no brake light activation. It seems fairly common for the lights to only come on a few feet before I stop.

This 100%. I often come to a stop without the brake lights activating until just before coming to a complete stop. As such, I have to watch and increase braking (less throttle application) to make sure the lights actually come on and I don't like it. My MINI EV activated the brake lights with much less deceleration. I've gotten to a point where I can feel it and know when the lights come on, but it's still more braking than I want, especially in stop and go traffic.

Next question: Is there any way to flash the brake lights while stopped?

While actually stopped...no. I did discover that you can use your left foot to very lightly apply the brake pedal while either driving normally or using regen braking to illuminate the brake lights without activating the friction brakes.

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[rpmtexas]

This 100%. I often come to a stop without the brake lights activating until just before coming to a complete stop. As such, I have to watch and increase braking (less throttle application) to make sure the lights actually come on and I don't like it. My MINI EV activated the brake lights with much less deceleration. I've gotten to a point where I can feel it and know when the lights come on, but it's still more braking than I want, especially in stop and go traffic.

In studying this a little further, I realized it’s way worse if you’re going uphill as that contributes to the deceleration. So the problem is potentially magnified in hilly areas.

 

[Whataboykie!]

Yeah I have always wondered at what level of deceleration does the brake lights come on?
As I pass another vehicle, the Rivian accelerates from say 40 mph to 70 mph in just seconds.
This means that you blow by these vehicles at speeds they don't really imagine.
When passed, I then let off the gas to get back to a normal speed. I've always wondered if I then seem to brake-check the guy I just passed?
I didn't know about the light on the screen showing when the brake light come on. I will check that.

 

[Singletracker]

Not sure if it has previously been noted, but the dash brake light indicator is on the picture of the Rivian. It shows a faint, reddish display at the back of the Rivian pic when the brake lights are on. I actually think it could be a little brighter. It‘s almost hard to notice if you are not looking for it.

 

[Glongo]

Not sure if it has previously been noted, but the dash brake light indicator is on the picture of the Rivian. It shows a faint, reddish display at the back of the Rivian pic when the brake lights are on. I actually think it could be a little brighter. It‘s almost hard to notice if you are not looking for it.

I noticed that red light pretty quickly. It helped my quickly understand the basic parameters for the brake lights. This thread really nails down the deployment triggers, so can I ask if anyone has experienced times when the regen (not light but regen function) is off? I noticed the other day on two occasions that if was not engaged for a short period. There maybe another thread on this, but this was the scenario on both: 10 minutes into a normal drive in town, traveling 40-ish mph, traffic slowing, lifted pedal and no regen. It was temporary and I changed no settings before or after. Was it a bug or some logic based reaction?

 

[SANZC02]

Yeah I have always wondered at what level of deceleration does the brake lights come on?
As I pass another vehicle, the Rivian accelerates from say 40 mph to 70 mph in just seconds.
This means that you blow by these vehicles at speeds they don't really imagine.
When passed, I then let off the gas to get back to a normal speed. I've always wondered if I then seem to brake-check the guy I just passed?
I didn't know about the light on the screen showing when the brake light come on. I will check that.

The brake lights have a regulation for when they need to come on based on deceleration rate. EVs are safer than manual transmission where the brake lights were only triggered by brake pedal and not by lifting off the throttle.

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

 

[Milermore]

We have all had the experience of driving behind somebody that is constantly on and off their brakes. You know - the persistent tailgater, erratic on and off the gas/brakes, two foot, etc drivers. It can be annoying watching those brake lights constantly cycling, often times for no good reason. My question is - using one pedal driving, when does the vehicle activate the brake lights? Surely, this can’t happen every time one lets off the throttle a little, just to gradually slow a bit. Is there a sensor that monitors the actual rate of deceleration and then controls the brake lights accordingly? Just curious

Yes. As others mentioned, sensors measure deceleration and turn on brake lights when thresholds are met.
I coast more without applying brake when I drive an ICE vehicle, and when I'm driving EV's the brake light comes on more often. I probably have set off one or more ICE drivers unaware of the automated lights, thinking I'm brake-checking them.
I try to minimize it with a soft foot in one-pedal driving.

 

[AxelR]

I guess some here have never driven a manual car and used engine break/ downshifted. Break lights don’t light up.
The rest of the world has been okay with this for decades…
Maybe increase your safety distance between your vehicle and the one ahead of you.
Edit: or the one following you…

 

[SoCal Rob]

Next question: Is there any way to flash the brake lights while stopped?

So now I have my R1S, and I have been glancing at the little cartoon of my vehicle while driving and I generally agree with the threshold Rivian chose to activate the brake lights.

Now I want a way to grab the attention of the distracted driver behind me who doesn't notice that I'm stopped in the lane and they are barreling toward me from behind. In my driver's ed class, they taught us to pump the brakes rapidly to flash our brake lights in this scenario. I guess I'll retrain myself to hit the overhead hazard lights button, but the flash rate seems too slow to really grab attention...

I use the hazards for rapid/unexpected stops in general. I think they’re more effective on cars with amber turn signals at the back since the only time you have amber on both sides at the same time is for hazards. Still, the Rivian’s hazard lights are very bright.

I thought the flash rate was low at first, but then I realized my mind was playing tricks on me. They sound half as fast as most other turn signals because there is a single (tap) sound per on/off cycle whereas all other vehicles I can recall have a (click) sound for on and a different pitched (clack) sound for off. Hopefully that description makes sense.

 

[WorldComposting]

I guess some here have never driven a manual car and used engine break/ downshifted. Break lights don’t light up.
The rest of the world has been okay with this for decades…
Maybe increase your safety distance between your vehicle and the one ahead of you.

I have driven manual but I'm not worried about the distance in front of me it is the distracted driver behind me who is 10 feet from my bumper. Brake lights help get them to notice or give a warning if you are slowing down.

As for me I now drive with two feet when someone is tailgating to ensure the person notices I'm braking.

Of course this is all based on the lights on the dash being accurate for when the brakes light up which I'm guessing they are.

 

[Singletracker]

Yeah, I guess one needs to pay a little more attention to the inattentive trailing drivers. Have I mentioned how much I hate tailgaters To me, under normal driving conditions, they are either (A)completely clueless or (B)threatening an assault upon the driver(s) they are crowding. Either way, they are a road hazard and appropriate brake light function to keep from getting plowed into is critical.

 

[SANZC02]

I have driven manual but I'm not worried about the distance in front of me it is the distracted driver behind me who is 10 feet from my bumper. Brake lights help get them to notice or give a warning if you are slowing down.

As for me I now drive with two feet when someone is tailgating to ensure the person notices I'm braking.

Of course this is all based on the lights on the dash being accurate for when the brakes light up which I'm guessing they are.

What he is suggesting with leaving more room in front is you slow down slower and have room to move forward when the guy behind you is late to brake. They also will usually try to go around you if they think your following distance is excessive which totally solves the issue.

Works well been using this technique for years.

 

[rpmtexas]

The brake lights have a regulation for when they need to come on based on deceleration rate. EVs are safer than manual transmission where the brake lights were only triggered by brake pedal and not by lifting off the throttle.

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

Nope. Not a US reg.

 

[SANZC02]

Nope. Not a US reg.

Technically you are correct, it is not a US statute but is an international standard so any vehicle planned to be sold outside of the US needs to comply.

“
But back to the original question; the folks at NHTSA have given it some thought, and buried in a chart in Title 49 of the Code of Federal Regulationswhere they specify that stop lamps are required to come on when the brake pedal is engaged, they add that stop lamps “may also be activated by a device designed to retard the motion of the vehicle.” This gives manufactures permission to turn the brake lights on during regenerative braking. Here’s a bit of trivia to throw out the next time you want to be the life of the party: Even though pretty much everyone uses the term “brake lights”, in legal documents at the state, federal and international level, it’s “stop lamps.” While I can’t find any requirement in a US statute that requires manufacturers to activate stop lamps during regenerative braking, there is an international rule. The United Nations (who knew they were involved in vehicle safety requirements) has a work group that creates rules to harmonize vehicle safety on a global level. Their code specifies requirements for when stop lamps should illuminate based on deceleration in meters per second when using regenerative braking.

Even though there isn’t a similar requirement in the US, in order for vehicle manufacturers to compete globally, they have to comply with the UN’s rule. If you drive an electric car that is sold internationally you most likely have stop lamps that come on when you use regenerative braking and reach the deceleration threshold set by the UN standards. Next time you’re driving at night, check your rear view mirror when the regenerative braking comes on. You may be able to see your brake lights reflecting off nearby surfaces.”

 

[rpmtexas]

Technically you are correct, it is not a US statute but is an international standard so any vehicle planned to be sold outside of the US needs to comply.

“
But back to the original question; the folks at NHTSA have given it some thought, and buried in a chart in Title 49 of the Code of Federal Regulationswhere they specify that stop lamps are required to come on when the brake pedal is engaged, they add that stop lamps “may also be activated by a device designed to retard the motion of the vehicle.” This gives manufactures permission to turn the brake lights on during regenerative braking. Here’s a bit of trivia to throw out the next time you want to be the life of the party: Even though pretty much everyone uses the term “brake lights”, in legal documents at the state, federal and international level, it’s “stop lamps.” While I can’t find any requirement in a US statute that requires manufacturers to activate stop lamps during regenerative braking, there is an international rule. The United Nations (who knew they were involved in vehicle safety requirements) has a work group that creates rules to harmonize vehicle safety on a global level. Their code specifies requirements for when stop lamps should illuminate based on deceleration in meters per second when using regenerative braking.

Even though there isn’t a similar requirement in the US, in order for vehicle manufacturers to compete globally, they have to comply with the UN’s rule. If you drive an electric car that is sold internationally you most likely have stop lamps that come on when you use regenerative braking and reach the deceleration threshold set by the UN standards. Next time you’re driving at night, check your rear view mirror when the regenerative braking comes on. You may be able to see your brake lights reflecting off nearby surfaces.”

I’ve read all the regs. They are extremely basic with no actual standards. Regen braking failing to activate brake lights is well documented, including in vehicles from non-US manufacturers. A UN standard is basically an aspiration, like the ABA model rules, with no teeth. And just because a company may plan to sell something in a foreign country absolutely does not mean an unenforceable UN standard would be followed in the US. Standards aren’t even consistent in the US for many things.

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