Regen Braking and Brake Lights

[chucky0731]

Hi...I'm a newbie in turns of EV driving since the Lucid is my 1st EV.

I have been using the regenerative braking almost exclusively (95% of time) to stop the vehicle. So my question is...when I use the regen braking to stop my vehicle, does the rear brake lights activate to alert the driver behind that I am slowing down?

 

[Adnillien]

Hi...I'm a newbie in turns of EV driving since the Lucid is my 1st EV.

I have been using the regenerative braking almost exclusively (95% of time) to stop the vehicle. So my question is...when I use the regen braking to stop my vehicle, does the rear brake lights activate to alert the driver behind that I am slowing down?

Yes they do.

 

[Bobby]

Hi...I'm a newbie in turns of EV driving since the Lucid is my 1st EV.

I have been using the regenerative braking almost exclusively (95% of time) to stop the vehicle. So my question is...when I use the regen braking to stop my vehicle, does the rear brake lights activate to alert the driver behind that I am slowing down?

That’s a really good question and the answer is yes. I do wish I knew WHEN it was activating the brake lights. How strong of a regen? What if I just let off a little on the freeway? I wish the little icon on the dash would have brake lights that light up to indicate.

 

[LucidMike]

That’s a really good question and the answer is yes. I do wish I knew WHEN it was activating the brake lights. How strong of a regen? What if I just let off a little on the freeway? I wish the little icon on the dash would have brake lights that light up to indicate.

I agree..I appreciated the brake light indicator in my 2015 Tesla and I assume it would be a simple software update to add it to the Lucid dash.

 

[Dog poop]

I agree. It would be nice to have a marker on the regen side of the speedometer to see when it triggers.

 

[Steveinarizona]

There are several locations in the US where Lucid owners get together for a drive. I know that there is such a group in Scottsdale and a get together trip is scheduled soon. Perhaps someone in the back of the group could comment on what she/he sees.

 

[Matthew-345]

Though I believe they do come on, I don't believe they come on as often as they should. The rate of deceleration should be revisited to determine a more real-world value for when the lights activate. Multiple people have told me they nearly ran into me and thought my brake lights weren't working.

 

[CrewChief]

Though I believe they do come on, I don't believe they come on as often as they should. The rate of deceleration should be revisited to determine a more real-world value for when the lights activate. Multiple people have told me they nearly ran into me and thought my brake lights weren't working.

Today I did an unscientific experiment to check out where in the slow-down (regen) process the brake lights come on. I checked a number of data points at various speeds using a vehicle to follow me. Bottom line was that the brake lights tended to come on in a similar fashion as you would expect with an ICE vehicle with conventional braking. That is using regen to slow down was similar to the engine braking you would expect from a manual transmission to a point about half way through the first quadrant with no brake light activation.
More specifically, if you were to consider the regen gage starting at 0 degrees then increasing in a counter clockwise direction up to 90 degrees through the first quadrant the brake lights tended to come on after 45 degrees or roughly half way through the first quadrant on the gage.
For me in my Touring this was pretty much the case in all three drive modes and in both regen settings.
With hard lifting off the accelerator, the regen gage quickly goes past the first quadrant (90 degrees) and brake lights come on instantly.
Hope this gives a little insight without being too verbose and confusing. If so, kindly disregard!!!

 

[Bobby]

Today I did an unscientific experiment to check out where in the slow-down (regen) process the brake lights come on. I checked a number of data points at various speeds using a vehicle to follow me. Bottom line was that the brake lights tended to come on in a similar fashion as you would expect with an ICE vehicle with conventional braking. That is using regen to slow down was similar to the engine braking you would expect from a manual transmission to a point about half way through the first quadrant with no brake light activation.
More specifically, if you were to consider the regen gage starting at 0 degrees then increasing in a counter clockwise direction up to 90 degrees through the first quadrant the brake lights tended to come on after 45 degrees or roughly half way through the first quadrant on the gage.
For me in my Touring this was pretty much the case in all three drive modes and in both regen settings.
With hard lifting off the accelerator, the regen gage quickly goes past the first quadrant (90 degrees) and brake lights come on instantly.
Hope this gives a little insight without being too verbose and confusing. If so, kindly disregard!!!

Well described.

 

[CrewChief]

Today I did an unscientific experiment to check out where in the slow-down (regen) process the brake lights come on. I checked a number of data points at various speeds using a vehicle to follow me. Bottom line was that the brake lights tended to come on in a similar fashion as you would expect with an ICE vehicle with conventional braking. That is using regen to slow down was similar to the engine braking you would expect from a manual transmission to a point about half way through the first quadrant with no brake light activation.
More specifically, if you were to consider the regen gage starting at 0 degrees then increasing in a counter clockwise direction up to 90 degrees through the first quadrant the brake lights tended to come on after 45 degrees or roughly half way through the first quadrant on the gage.
For me in my Touring this was pretty much the case in all three drive modes and in both regen settings.
With hard lifting off the accelerator, the regen gage quickly goes past the first quadrant (90 degrees) and brake lights come on instantly.
Hope this gives a little insight without being too verbose and confusing. If so, kindly disregard!!!

Additionally, I use the “Hold” function and the brake lights remain activated as the car is stopped in “Drive” as would be desired, until the accelerator is engaged again.

 

[Adnillien]

Today I did an unscientific experiment to check out where in the slow-down (regen) process the brake lights come on. I checked a number of data points at various speeds using a vehicle to follow me. Bottom line was that the brake lights tended to come on in a similar fashion as you would expect with an ICE vehicle with conventional braking. That is using regen to slow down was similar to the engine braking you would expect from a manual transmission to a point about half way through the first quadrant with no brake light activation.
More specifically, if you were to consider the regen gage starting at 0 degrees then increasing in a counter clockwise direction up to 90 degrees through the first quadrant the brake lights tended to come on after 45 degrees or roughly half way through the first quadrant on the gage.
For me in my Touring this was pretty much the case in all three drive modes and in both regen settings.
With hard lifting off the accelerator, the regen gage quickly goes past the first quadrant (90 degrees) and brake lights come on instantly.
Hope this gives a little insight without being too verbose and confusing. If so, kindly disregard!!!

I really like it when people take time to collect data and share that with the Lucid community. It takes a bit work but is really helpful to the Lucid community.

 

[hydbob]

Today I did an unscientific experiment to check out where in the slow-down (regen) process the brake lights come on. I checked a number of data points at various speeds using a vehicle to follow me. Bottom line was that the brake lights tended to come on in a similar fashion as you would expect with an ICE vehicle with conventional braking. That is using regen to slow down was similar to the engine braking you would expect from a manual transmission to a point about half way through the first quadrant with no brake light activation.
More specifically, if you were to consider the regen gage starting at 0 degrees then increasing in a counter clockwise direction up to 90 degrees through the first quadrant the brake lights tended to come on after 45 degrees or roughly half way through the first quadrant on the gage.
For me in my Touring this was pretty much the case in all three drive modes and in both regen settings.
With hard lifting off the accelerator, the regen gage quickly goes past the first quadrant (90 degrees) and brake lights come on instantly.
Hope this gives a little insight without being too verbose and confusing. If so, kindly disregard!!!

Curious, how did you track it? Put a mirror on the back? Drive at night to see? Have a follow car?

 

[CrewChief]

Curious, how did you track it? Put a mirror on the back? Drive at night to see? Have a follow car?

Had a follow car

 

[CrewChief]

Had a follow car

My overall assessment is that the brake lights are quite well dialed in such that as I was slowing gradually and generally would not want the brake lights engaged, they didn’t. And as I backed off a bit more aggressively with more regen kicking in, the brake lights engaged just about exactly the way I would want.
I do, however, agree with others’ suggestions that an indicator in the regen gage showing when the brake lights have engaged would be an excellent feature to help drivers develop a cadence or muscle memory for the brake light engagement.
In addition, it would be useful to know how the brake lights engage when using cruise control, which I did not check yet.
Possibly someone from Lucid could weigh in here to add some present and future perspective to this topic.

 

[joec]

My overall assessment is that the brake lights are quite well dialed in such that as I was slowing gradually and generally would not want the brake lights engaged, they didn’t. And as I backed off a bit more aggressively with more regen kicking in, the brake lights engaged just about exactly the way I would want.
I do, however, agree with others’ suggestions that an indicator in the regen gage showing when the brake lights have engaged would be an excellent feature to help drivers develop a cadence or muscle memory for the brake light engagement.
In addition, it would be useful to know how the brake lights engage when using cruise control, which I did not check yet.
Possibly someone from Lucid could weigh in here to add some present and future perspective to this topic.

Nice work. One would expect the folks at Lucid to want to get this right, and for the various regulatory agencies to demand it. But it’s good to have confirmation with actual test data. Thanks for posting.

 

[Matthew-345]

Today I did an unscientific experiment to check out where in the slow-down (regen) process the brake lights come on. I checked a number of data points at various speeds using a vehicle to follow me. Bottom line was that the brake lights tended to come on in a similar fashion as you would expect with an ICE vehicle with conventional braking. That is using regen to slow down was similar to the engine braking you would expect from a manual transmission to a point about half way through the first quadrant with no brake light activation.
More specifically, if you were to consider the regen gage starting at 0 degrees then increasing in a counter clockwise direction up to 90 degrees through the first quadrant the brake lights tended to come on after 45 degrees or roughly half way through the first quadrant on the gage.
For me in my Touring this was pretty much the case in all three drive modes and in both regen settings.
With hard lifting off the accelerator, the regen gage quickly goes past the first quadrant (90 degrees) and brake lights come on instantly.
Hope this gives a little insight without being too verbose and confusing. If so, kindly disregard!!!

Thanks for taking the time to test this out. I’m relieved knowing that they are coming on more frequently than I was originally led to believe.

 

[Cosmo Cruz]

It was my first thought to look at the "power flow" dial right in front of me (but behind the top of the steering wheel).
Glad to read that others have done the work of finding out the "when?" part.
thanks @CrewChief.

 

[davo44]

Thanks @CrewChief I was wondering the same thing!

 

[EVCar]

I've read this thread and other postings.
I've had someone follow me in another car.
To this date, I'm still not sure.
Sometimes I can confirm the posted info; sometimes, not.
And it's entirely possible that I didn't take into account variables that I didn't think about.
It'd be so helpful if Lucid and all car manufactures just publicize how the brake light works in their cars.
Or maybe this is a trade secret?
It's a safety issue and I want to be to do whatever necessary to adapt to the car's operating parameters.

 

[AnthonyInCO]

Watched a YT video on this matter and came to the forum in a panic wondering if my beloved Lucid is failing this key functionality - properly illuminating the brake light when decelerating by regen. Wish Lucid would publish spec on what triggers it.

This YT video by Technology Connections mentions that the EU recently patched up their regs on when brake lights come one, setting it at min (or max?) of 1.3m/s^2 deceleration, but looks like NHTSA has not done so yet. It's a long video, but very interesting and well-researched.

Anyone have an accelerometer to add some further data to @CrewChief 's experiment? Can't our phones do that? Is there an app for that?