Brake light function with one pedal driving?

[rpmtexas]

Go to page 93 of your R1T manual - https://assets.rivian.com/2md5qhoea...05dfa95a4e059ba4251/r1t-og-en-us-20230327.pdf

All EVs activate the brake lights under regenerative braking although I'm not sure if it's only at certain speeds. You can see them illuminate as you approach a stop sign with no pressure on either pedal.

All EVs do not.

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[godfodder0901]

All EVs do not.

All EVs are federally mandated to do so if they apply enough deceleration.

 

[rpmtexas]

All EVs are federally mandated to do so if they apply enough deceleration.

“Enough” being the operative word there. Vehicles can slow down significantly without break lights coming on. Also, if person lifts hard and the pushes more it will still be regen but less and turns off the break lights in some vehicles. It’s a known issue. You can read up on it.

 

[Craigins]

“Enough” being the operative word there. Vehicles can slow down significantly without break lights coming on. Also, if person lifts hard and the pushes more it will still be regen but less and turns off the break lights in some vehicles. It’s a known issue. You can read up on it.

It isn't an issue... It is designed to the federally mandated specifications.

If you want stricter requirements in the spec, write to your congress representative.

 

[rpmtexas]

It isn't an issue... It is designed to the federally mandated specifications.

If you want stricter requirements in the spec, write to your congress representative.

Consumer reports disagrees with you. “In spite of the potential safety hazard presented by the failure of brake lights to illuminate during one-pedal driving, the U.S. government doesn’t have an explicit standard regarding deceleration levels for activating brake lights.” And the National Highway and Transportation Safety Administration does too. The federal regulations do “not require the [stop] lamps to be activated at a specific level of deceleration.” Thus, Rivian could not have “designed to the federally mandated specifications” since there are none. The federal regulation only requires that the stop lamps “Must be activated upon application of the service brakes. …
May also be activated by a device designed to retard the motion of the vehicle.” So they MAY be activated by other means. Hopefully they work well, but it would be good if there was an actual standard.

 

[Craigins]

Consumer reports disagrees with you. “In spite of the potential safety hazard presented by the failure of brake lights to illuminate during one-pedal driving, the U.S. government doesn’t have an explicit standard regarding deceleration levels for activating brake lights.” And the National Highway and Transportation Safety Administration does too. The federal regulations do “not require the [stop] lamps to be activated at a specific level of deceleration.” Thus, Rivian could not have “designed to the federally mandated specifications” since there are none. The federal regulation only requires that the stop lamps “Must be activated upon application of the service brakes. …
May also be activated by a device designed to retard the motion of the vehicle.” So they MAY be activated by other means. Hopefully they work well, but it would be good if there was an actual standard.

So I dug up our thread from 2 years ago about brake lights on the tail gate, where I originally read the regulations. I couldn't find any links to the regulations and google is not giving me the document I read in the past. Sad. Usually I link that stuff when I find it.

 

[Craigins]

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

 

[JWreck]

Here’s a great video that outlines why, objectively, this really is a problem. It highlights Hyundai/Kia but applies to most EVs, though some are slightly better than others.

 

[Craigins]

Here’s a great video that outlines why, objectively, this really is a problem. It highlights Hyundai/Kia but applies to most EVs, though some are slightly better than others.

The issue with regenerative braking and the stop lamp triggering has more to do with emulating deceleration when ICE vehicles would be "coasting."

Each ICE vehicle coasts differently. Where is the line for deceleration between "brake pedal" and "coast"?

Personally I think they could activate the lights at less deceleration than they currently do, but I don't have an exact value that represents when I think they should come on.

If it is too light, the everyone will look like they are "riding the brake."

 

[JWreck]

The issue with regenerative braking and the stop lamp triggering has more to do with emulating deceleration when ICE vehicles would be "coasting."

Each ICE vehicle coasts differently. Where is the line for deceleration between "brake pedal" and "coast"?

Personally I think they could activate the lights at less deceleration than they currently do, but I don't have an exact value that represents when I think they should come on.

If it is too light, the everyone will look like they are "riding the brake."

The US adopting the new EU regs would be a step in the right direction. I agree that there is a possible over correction that could happen which we don’t want either.

Re: ICE coasting….unless engine braking, no ICE decelerates like most EVs when coasting (including something like the Taycan which doesn’t really employ strong lift off regen). It’s certainly easier then, to say that the trigger is “brake pedal pressed” because an ICE vehicle won’t considerably slow down under normal/default circumstances otherwise.

 

[Craigins]

Re: ICE coasting….unless engine braking, no ICE decelerates like most EVs when coasting (including something like the Taycan which doesn’t really employ strong lift off regen). It’s certainly easier then, to say that the trigger is “brake pedal pressed” because an ICE vehicle won’t considerably slow down under normal/default circumstances otherwise.

You're misinterpreting what I was referencing with coasting.

Let me first establish an assumption that regenerative braking is not an all-or-nothing feature. Nobody should be driving with regenerative braking by removing their foot completely from the pedal every time they want to initiate a stop.

With that assumption, coasting in an ICE vehicle, represents a position on the accelerator in an EV with single pedal driving enabled.

Thus you need to determine at which point on the travel of the pedal switches between ICE coasting and ICE lightly pressing the brake.

Since each ICE vehicle is different, there is no single point where you could say "this is coasting" vs "this is braking". I had one truck that was geared to the point where taking my foot off the gas pedal drastically slowed me down. Then again, my family had a Mercury Sable that would "coast" at 20mph. Clearly 2 extremes there.

Thus you're left with a few choices, go by the existing UN standard which dictates when you MUST illuminate the lights, or spend money to do a performance study to get an average deceleration rate for coasting ICE vehicles.

 

[RivLiam]

There have been really good reasons NOT to tailgate since the second automobile hit the road. It used to be, that everything had a manual transmission. Some still are.

It used to be the "normal" way to drive was to upshift to continue accelerating and then downshift to slow down. No amount of downshifting ever activated a tail light. People actually had to pay attention to the vehicle that was in front of them.

Nowdays, we have metric sh*t tons of drivers who have no idea what to do with a clutch and stick shift. Most people no longer "drive"...they just "aim"....[end of rant.]

This was my first thought, plenty of time behind a manual growing up and I rarely touched the brake pedal and you can REALLY slow down a manual by dropping gears without so much as a warning.

I do have to say the fact that brakes are built into the accelerator does make it feel like you're driving an automatic with both feet on the pedals all the time so I can see how someone who doesn't drive an EV curious about braking situation since I can pump my foot and go blisteringly fast and then 'slam' on the brakes with a few inches of foot flexion.

 

[rpmtexas]

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. Also, the lights sometimes cut in and out when coming to a stop as I am feathering the peddle so the stop is smooth. This is a bad situation as a driver could interpret the brake lights going out as acceleration. Personally I prefer the Audi method of putting the regen in the brake pedal. Allows you to coast and regen braking activates brake lights.

 

[godfodder0901]

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. Also, the lights sometimes cut in and out when coming to a stop as I am feathering the peddle so the stop is smooth. This is a bad situation as a driver could interpret the brake lights going out as acceleration. Personally I prefer the Audi method of putting the regen in the brake pedal. Allows you to coast and regen braking activates brake lights.

This doesn't match my experience at all. I can usually come to a complete, smooth stop while feathering the accelerator pedal and the brake lights almost never extinguish. If they do, it's only for the last few inches before auto hold kicks on and illuminates the brake light for me.

 

[tragicmonkey049]

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...

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