Something positive for a change

[Deleted member 14300]

I've never seen this before, but when you come off the throttle, the brake lights activate. I've never seen this before.

 

[Archev]

I've never seen this before, but when you come off the throttle, the brake lights activate. I've never seen this before.

That’s your regen braking indication to the folks following you

 

[Themist0]

I wonder if it comes on immediately or waits for the car to be actually slowing continuously… for example if you lift off slightly on the motorway will the people following you get an instant brake light. Normal cars that coast, don’t have brake lights come on at all.

 

[Archev]

I wonder if it comes on immediately or waits for the car to be actually slowing continuously… for example if you lift off slightly on the motorway will the people following you get an instant brake light. Normal cars that coast, don’t have brake lights come on at all.

Good point - but coasting equals no powered travel so friction and wind drag are going to degrade your speed at least to some extent so is it not better to alert those behind ??

 

[siteguru]

Anecdotally they come on when the regen % hits 7%. The actual answer is that they must come on when the retardation rate (how quickly you're slowing down) reaches/exceeds 1.3 m/s² (metres per second squared), but a manufacturer may choose for them to come on earlier.

More info for insomniacs here:

https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:42023X0401

 

[Koomi]

Thanks - I was going to get the missus to follow in the other car, on hands free, and see at what point the light comes on.

As you don't want the brake to flash if you slightly lift off and are on -3 or -4, but then stronger regen should show the lights - just at what point does that happen... I was thinking about -10%, so 7% is close enough and a good target to keep below when just coasting as not to annoy those behind

 

[Rolfe]

It can look a bit weird. One day I was following a Leaf along a winding road and I thought, that's weird, why is he constantly braking in these strange places? Then I realised it was his regen coming on when he took his foot off the accelerator.

 

[Expat Ever]

There's a very good You Tube video on this subject and the move to get some uniform legislation introduced in the US.

 

[Flightengineer]

Hello. If somebody tried to perform this test? When brake lights really switch on?

 

[mg4mc]

I've tried to catch my lights reflection in a following car and the best I could do was they come on at 10% regen (±)

 

[SimonS]

I saw a Tesla M3 on the M6 with the brake lights doing all sorts of weird stuff.

 

[mg4mc]

Anecdotally they come on when the regen % hits 7%. The actual answer is that they must come on when the retardation rate (how quickly you're slowing down) reaches/exceeds 1.3 m/s² (metres per second squared), but a manufacturer may choose for them to come on earlier.

More info for insomniacs here:

https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:42023X0401

Weird, a quick read on my phone (so could be wrong) indicates that "emergency braking systems" don't need to put the brake lights on until 6 m/s² ?

 

[QLeo]

Hello. If somebody tried to perform this test? When brake lights really switch on?

We live in a very rural area, with little light pollution, so yes, I wanted to test this, and it was easy to see when the brake lights came on in the rear view mirrors. I do not think it is related to percentage regen only, but mostly to actually slowing down. Having said that, on a very steep hill, where I did not think the car was slowing down, the brake lights were on - the car would accelerate under gravity without regen, so that must have been on percentage.

In short, from what I could tell on our hilly roads, "it's complicated". But the main thing I wanted to learn is whether the brake lights come on immediately on regen. They don't. It still leaves you with a slight feeling that anyone following may think you're driving fearfully, hovering on the brakes, but as EVs become more ubiquitous, there'll be wider understanding, I am sure.

 

[Tuareg]

Who cares what those driving behind think? It's not illegal to have brake lights on when the car is slowing at any rate

 

[OriginalBigAl]

There are plenty of YT videos of deliberate brake checking , mainly USA , some Britain, and causing a bit of argy bargy. All it takes is some uneducated moron following you thinking they are winding me up, and there's going to be a bit of road rage, 0-60 time might come in handy, easier than trying to explain the technicalities of regen braking.

 

[QLeo]

Who cares what those driving behind think? It's not illegal to have brake lights on when the car is slowing at any rate

No, of course not. But if the brake lights come on at unexpected times, it could be seen as inconsistent driving, which can be dangerous. So I'd rather understand when the lights are likely to come on. It's just trying to be courteous.

 

[siteguru]

If you drive in regen mode 1 then I don't think the lights will come on when you're coasting (no accelerator and no brake). That mode is quite like an automatic ICE coasting, with minimal engine braking. Thus you'd be able to control when the brake lights come on.

 

[Deleted member 14300]

In a normal high regen, yes the brake lights come on as you slowly decelerate because of the motors.