Question about regen and brake lights

[PhillyTCT4S]

Not sure if this is normal so I would appreciate some feedback.

Recently I changed my rear light bar to the one with led letters. All went well and everything works fine together with brake lights.

What I noticed is that when the car uses regen (regen option ON or Auto) I dont see that my brake lights are on untill I actually press the brake pedal.

Not sure if this is normal. I am comparing this to my wife's Tesla Y in which the lights come on almost instantly when you let go of the gas pedal and the car starts to regen.

Any ideas?

Thanks.

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[Sar]

I've wished for many years that cars would adopt a scalar approach to brake lights (the harder someone is braking, the stronger their red light). I was just noticing a few days ago with my own Taycan that the moment my foot barely touches the brake pedal, the lights turn on. I have my car set to coast (no auto regen braking and no artificial "engine brake simulation").

I was actually surprised to realize this, because if I softly press my brake pedal, my car doesn't even slow down at all. Certainly not as much as natural engine braking. Yet the light is there to scare everyone. I suppose I'm glad the car is erring on the side of caution by scaring everyone. The opposite of your situation.

 

[69Mach390]

Not sure if this is normal so I would appreciate some feedback.

Recently I changed my rear light bar to the one with led letters. All went well and everything works fine together with brake lights.

What I noticed is that when the car uses regen (regen option ON or Auto) I dont see that my brake lights are on untill I actually press the brake pedal.

Not sure if this is normal. I am comparing this to my wife's Tesla Y in which the lights come on almost instantly when you let go of the gas pedal and the car starts to regen.

Any ideas?

Thanks.

It’s normal.

Tesla uses 1 pedal drive. We have minimal off throttle regen. They are very different.

Much like a gas powered car, brake lights come on when you hit the brakes, even if you’re in a manual transmission car and slow down quickly using the engine.

 

[PhillyTCT4S]

Got it. Not so minimal regen anymore as I asked to increase it slightly when I purchased a tune Thanks for confirming that its normal.

 

[69Mach390]

Got it. Not so minimal regen anymore as I asked to increase it slightly when I purchased a tune Thanks for confirming that its normal.

You’d have to ask the tuner, but not sure if whatever controls the regen affects the brake lights “logic.”

It wasn’t any different with my last car (Mach E). You could hit the “low” button and have significant regeneration (same as the highest non-1 pedal drive unbridle setting) and the brake lights wouldn’t come on unless you touched the brake pedal. Similar to what would happen if you downshift in a gas car.

If you’re coming from a Tesla and used to significantly more regen from 1PD, this is definitely different.

I used to drive 2PD in my Mach E in the middle regen setting. But that was even more than the Taycan. The coasting takes some getting used to, but I appreciate it’s more efficient. The Mach E could never truly coast as the motors never disengaged.

 

[kempez]

@WuffvonTrips posted this a while ago. Not sure if Taycan complies, but I guess it will do/should do!

https://www.taycanforum.com/forum/threads/brake-lights-during-recuperation.15786/post-247435

 

[69Mach390]

@WuffvonTrips posted this a while ago. Not sure if Taycan complies, but I guess it will do/should do!

https://www.taycanforum.com/forum/threads/brake-lights-during-recuperation.15786/post-247435

That’s a lot of math and no clue how to calculate it.
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
In all cases the signal shall be de-activated at the latest when the deceleration has fallen below 0.7 m/s².


We do have a G force meter and 1 G = 9.8 m/s². The problem is it isn’t that precise to see 0.7.

If you really want to nerd out on it, you could drive to 10 m/s (22 mph), take your foot off the accelerator and see how far you travel in how much time before hitting 11 mph (5 m/s) and do that math.

Still might be imprecise if you don’t know that the road is perfectly flat or not.

 

[PhillyTCT4S]

The tune had no affect on the brake lights logic but with adjusted regen, which in my case is probably 40% stronger now the car will start reducing speed faster without engaging brake lights. Not a problem unless someone will be tailgating me too close....

 

[kempez]

Yeah I'm not going to pretend to be able to calculate it, but I guess at least there are standards to follow.

I am sure I have seen a Porsche presentation on here somewhere with an explanation from them how and when they enable the brake lights to be switched on, but I couldn't find it

 

[69Mach390]

The tune had no affect on the brake lights logic but with adjusted regen, which in my case is probably 40% stronger now the car will start reducing speed faster without engaging brake lights. Not a problem unless someone will be tailgating me too close....

Just a reminder then to “always watch your six!”

Anyone who tailgates a Porsche requires excellent insurance, fast reflexes and extreme confidence in their brakes.

 

[PhillyTCT4S]

Good point thats why I installed front and back cameras. Just in case

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