Brake lights during recuperation?

[tbinmd]

Sometime ago I tested this in my wife's CT, on a dark road take your foot off the accelerator with region turned on and the brake lights do not come on, while the car is slowing.

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[R Benny Waered]

It also doesn't light up when you have it in AUTO mode even when it slows down from 80mph to 60mph. I tried accelerating to 80mph behind a car going 60-65mph on the freeway and let the auto recup slowed the car down.

Goodness! Sounds like it SHOULD?

 

[W1NGE]

Goodness! Sounds like it SHOULD?

Nope, it should not. Doesn't happen in an ICE vehicle so why would the behaviour be different in an EV?

 

[R Benny Waered]

Nope, it should not. Doesn't happen in an ICE vehicle so why would the behaviour be different in an EV?

Because it can ACTIVELY regen-brake at a rate far higher than lifting off in third in any ICE car... Auto regen based on distance to the slower car in front can be quite strong.

 

[WuffvonTrips]

Here's an example of an ICE vehicle activating brake lights under ACC. I'd certainly expect the Taycan ACC to activate the lights if it slows faster than the mandated threshold, but I don't have ACC to test it.

 

[W1NGE]

Because it can ACTIVELY regen-brake at a rate far higher than lifting off in third in any ICE car... Auto regen based on distance to the slower car in front can be quite strong.

Not in my experience nor would I rely (or trust) auto recuperation to slow the car on its own without reverting to the brake pedal. Many scenarios where this feature doesn't function well.

Pretty sure Porsche will have adopted all necessary regulations per region.

If retardation is severe as in an emerging stopping scenario auto brake assist would take over and the brake lights would activate (pulsate) as the actual brakes are being applied.

I think this is a non issue IMHO.

 

[R Benny Waered]

Personally, if its doing high retardation I'd want to know that car behind is getting some brake lights. I think ACC does but Auto Regen doesn't brake hard enough to warrant it?

I think I need to get my GoPros out and hover the drone over J32 of the very downhill mile of the M4 exit slip road E as this exactly the scenario I use Auto regen in and catch up slower exiting vehicles.

 

[tchavei]

I hope auto recup turns on the braking lights. I have my car for less than a week, 470km driven but 90% on highway so brake regen hasn't activated yet but the auto recup is working and is STRONG. On occasions it's far far greater than 'lifting your foot in an ICE car' and I could see the green bar doing a full quarter (12 o clock to 9 o clock) or more. If that doesn't trigger the brake lights, I'm eventually going to have a nasty surprise from behind.

 

[WuffvonTrips]

I hope auto recup turns on the braking lights. I have my car for less than a week, 470km driven but 90% on highway so brake regen hasn't activated yet but the auto recup is working and is STRONG. On occasions it's far far greater than 'lifting your foot in an ICE car' and I could see the green bar doing a full quarter (12 o clock to 9 o clock) or more. If that doesn't trigger the brake lights, I'm eventually going to have a nasty surprise from behind.

Have you noticed what the g-meter shows under those circumstances?

 

[tchavei]

Have you noticed what the g-meter shows under those circumstances?

Haven't had the chance yet but I will check. It definitely feels like a normal brake before entering a roundabout so you feel your body mass shifting forwards

 

[whitex]

I just came across an interesting bit of information. EU specifically forbids brake lights from being illuminated during EV regen/recuperation!

More details here. TLDR; in the US it's up to the manufacturer, while in EU it's forbidden.
Update: EU did just fix this regulation problem a couple of months ago.

 

[FrozenBerries]

I just came across an interesting bit of information. EU specifically forbids brake lights from being illuminated during EV regen/recuperation!

More details here. TLDR; in the US it's up to the manufacturer, while in EU it's forbidden.

Why would they… ban it instead of requiring it?

 

[whitex]

Why would they… ban it instead of requiring it?

I updated the original post, apparently they just fixed it in March of this year, so perhaps Taycans will have an update in a year, but maybe not for the US market.

 

[Tooney]

Brake Lights Can Fail to Provide Fair Warning on Some Electric Vehicles
Consumer Reports' tests discover potential safety issues with brake lights on EVs from Genesis, Hyundai, Kia, and Mercedes-Benz

https://www.consumerreports.org/car...provide-fair-warning-on-some-evs-a9533519285/

 

[WuffvonTrips]

I updated the original post, apparently they just fixed it in March of this year, so perhaps Taycans will have an update in a year, but maybe not for the US market.

I've just checked the version of the regs used in that video- they're the original ones from 2010.
The ones I posted in April this year are Revision 4 of Regulation 13-H, document dated 5th June 2018, and do require brake lights to illuminate on lift-off (above the specified deceleration threshold)-
https://www.taycanforum.com/forum/threads/regenerative-braking-setting.15633/post-239250
relevant sub-para-
5.2.22.4. Electric regenerative braking systems as defined in paragraph 2.17. of this Regulation, which produce a retarding force upon release of the accelerator control, shall generate the signal mentioned above according to the following provisions:
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.

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