EV's, regenerative braking, and brake lights.

[Brandane]

Can anyone familiar with EV's and regenerative braking please enlighten me... I understand that as soon as you lift your foot off the accelerator pedal, the brakes are lightly deployed automatically which provides some charge to the battery?
When this happens, do the rear brake lights come on (i.e. without touching the brake pedal)?

The reason I am asking is that this would go some way to explaining why so many drivers seem to brake for the slightest bend in the road these days (brake lights come on) when it is not necessary. In the old days this would be construed to be bad driving. But is it a by-product of the new technology? It might save me some "WTF?" moments if I know (as I am unlikely to ever own an EV).

 

[figbat]

Yes.

To correct your opening statement, when you lift off the motor becomes a generator, which creates a resistance to movement which slows the car down (quite sharply too if fully lifted off); the brakes are not actually engaged. This does illuminate the brake lights. There is a legal requirement to put brake lights on if there is a certain level of deceleration, although my EV puts the lights on as soon at the motor goes into ‘regen’, so even a tiny lift-off with slight deceleration will put the lights on.

It’s something I am aware and conscious of so drive accordingly, avoiding constant on-off on the accelerator.

 

[Specialeyes]

In my little BMW i3s the brake lights do come on when you lift off fully. In order to coast, you rest your foot on the throttle without applying any real pressure and that keeps the brake lights off. The threshold and the aggression of the regen' varies according to the drive mode (sport/comfort/eco/eco +) too in order to better suit the style of driving. It's a new skill to learn, and anyone driving it for the first time does tend to kangaroo a bit! I like to see how far I can drive without using the brakes, as you get pretty good at judging when to lift off to coast up to the back of a queue

 

[figbat]

Yep - I rarely use the brake pedal. Although the car is programmed to blend in physical brakes with the regen because it only acts on one axle and when the battery is full the regen is ineffective. My rear wheels get covered in more brake dust than the fronts.

 

[Drago]

Yes, lift your foot off hard/suddenly enough in regen mode and the brake lights will come on.

You can tell who's a crap driver with poor throttle control from the way the brake lights are constantly flickering on and off.

Like figgers above who (I think) has the same car as me (at least until mine goes on Friday) I like mine in the highest regen setting and drive it one pedal 98% of the time, which suits my olde world smooth Class 1 driving style to a tee.

On the F56 Mini electric (and the petrol ones too) the car will lightly app,y the rear brakes on its own under certain dynamic conditions to aid stability so we can indeed get more brake dust on the rear than the fronts.

 

[ebikeerwidnes]

Yes, lift your foot off hard/suddenly enough in regen mode and the brake lights will come on.

You can tell who's a crap driver with poor throttle control from the way the brake lights are constantly flickering on and off.

Like figgers above who (I think) has the same car as me (at least until mine goes on Friday) I like mine in the highest regen setting and drive it one pedal 98% of the time, which suits my olde world smooth Class 1 driving style to a tee.

On the F56 Mini electric (and the petrol ones too) the car will lightly app,y the rear brakes on its own under certain dynamic conditions to aid stability so we can indeed get more brake dust on the rear than the fronts.

so basically it encourages safe and efficient driving and looking ahead and thinking about it

Hmm - I think I can see the problem with that concept!

 

[markemark]

As mentioned, they come on depending on the level of regen breaking. Any light braking and they don’t. It’s at at certain point do they kick in.

 

[Beebo]

It’s a problem on motorways, as it gives the impression that you are braking when you aren’t.
And the car behind them brakes causing a domino effect.
I try to turn mine off on motorways, if I remember to do it.

 

[Drago]

I drive a smooth as a pint of Guinness poured through a satin sheet by Nigel Havers and don't have a problem. I can  just see the reflction of the 3rd brake light in the rear window so I can see if im waking it up or not.

 

[Dadam]

It’s a problem on motorways, as it gives the impression that you are braking when you aren’t.
And the car behind them brakes causing a domino effect.
I try to turn mine off on motorways, if I remember to do it.

It gives the correct impression you are decelerating when you are. The effect you describe has always been there before EVs were popular, and is caused by people driving too close to the car in front and not anticipating. I've never driven an EV but on a motorway I always try not to touch the brake the whole distance.

Regardless of regen braking, if more people drove like this, there would be fewer jams and accidents.

 

[Beebo]

It gives the correct impression you are decelerating when you are. The effect you describe has always been there before EVs were popular, and is caused by people driving too close to the car in front and not anticipating. I've never driven an EV but on a motorway I always try not to touch the brake the whole distance.

Regardless of regen braking, if more people drove like this, there would be fewer jams and accidents.

Exactly.
In my petrol engine car, I also try to never brake, but you can adjust speed slightly by lifting off the accelerator.
In my electric car, if I have it on a high regen setting, when I lift off, the car will slow far more dramatically than usual and the brake light will show. Even though I am not wanting to brake.

 

[ebikeerwidnes]

It is not a major problem as "normal" cars can slow down without engaging the brake light by changing down

even on my current automatic (actually CVT as it is a bit weird) I have flappy paddles and can slow down more efficently by changing down approaching traffic lights
EVs are just more likely to do it
but a half decent driver will have left enough space to allow for it


of course - not all drivers are decent drivers

 

[Grant Fondo]

I dont get much regen in my i4.
Thats why I get 100 miles on a full charge?

 

[figbat]

As mentioned, they come on depending on the level of regen breaking. Any light braking and they don’t. It’s at at certain point do they kick in.

On the MINI they come on with ANY regen, regardless of the deceleration rate. It’s one of only a small number of issues with an otherwise great car.

 

[markemark]

On the MINI they come on with ANY regen, regardless of the deceleration rate. It’s one of only a small number of issues with an otherwise great car.

That’s odd cos I have a BMW (same company) and it works differently.