Page 2 of 3

Re: Brake lights in B mode

Posted: Tue Jan 31, 2017 9:18 am
by DuncanCunningham
maybe a 'regen light' like the F1 Cars do during racing? They flash when the car is harvesting energy to warn the car behind to allow close racing.

Re: Brake lights in B mode

Posted: Tue Jan 31, 2017 10:04 am
by RonDawg
FWIW the VW eGolf's brake lights do come on if the needle on the power/regen gauge reaches the first white mark on the regen side. I don't know of other plug-in cars do that.

Image

Re: Brake lights in B mode

Posted: Thu Feb 09, 2017 3:30 pm
by IssacZachary
I've had the same problem in all my cars. I guess because I drive like I do in my school bus, I engine brake as much as possible. I loved double clutching my cars and watch pedestrians turn their heads in confusion of why I blipped the accelerator. I'm terrible at driving an automatic because I have to engine brake and shifting in and out of lower gears in an automatic can be a pain and sometimes I miss and put it in the wrong gear.

I do, however, lightly tap brake pedal a couple times when I downshift. In the Leaf just the slightest touch activates the brake lights.

Actually the B mode isn't as aggressive as third gear in my 1985 VW diesel Golf with it's 23:1 compression ratio.

Personally I wouldn't want B mode to activate the brake lights. When I go over a mountain pass and am motor braking down the other side I would want my brake lights to turn on when a dear or moose jumps out in front of me not the whole way down the mountain.

Re: Brake lights in B mode

Posted: Thu Feb 09, 2017 4:03 pm
by arnis
IssacZachary wrote: Personally I wouldn't want B mode to activate the brake lights. When I go over a mountain pass and am motor braking down the other side I would want my brake lights to turn on when a dear or moose jumps out in front of me not the whole way down the mountain.
EXACTLY. Leaf does not have Brake Force Display (which by my standards should be mandatory for now). This means if vehicle is trying to stop sharply brake lights will blink rapidly. And if vehicle stops after this incident, hazards will activate for some time.
Due to that I would not like one-level braking lights to be always engaged. And as soon as I brake heavily due to whatever reason rear person will not notice that.
As far as I have experience in my lifetime, ICE cars drivers (with automatic gearbox) who keep their foot on brake pedal (and don't even decelerate noticeable for more than few seconds) and then push pedal heavily and slow down fast are the hardest for me to notice.

Re: Brake lights in B mode

Posted: Thu Feb 09, 2017 7:06 pm
by IssacZachary
arnis wrote:EXACTLY. Leaf does not have Brake Force Display (which by my standards should be mandatory for now). This means if vehicle is trying to stop sharply brake lights will blink rapidly. And if vehicle stops after this incident, hazards will activate for some time.
Due to that I would not like one-level braking lights to be always engaged. And as soon as I brake heavily due to whatever reason rear person will not notice that.
As far as I have experience in my lifetime, ICE cars drivers (with automatic gearbox) who keep their foot on brake pedal (and don't even decelerate noticeable for more than few seconds) and then push pedal heavily and slow down fast are the hardest for me to notice.
Mmm... An automated braking level light system. Sounds like a good idea.
  • For me I just do that all manually.
  • If I'm slowing down little by little I flash my brake lights (tap the pedal) a couple of times here and there.
  • If I'm doing more than just engine/regen braking I'm braking and therefore my lights are on.
  • If I'm slamming on my brakes because a wapiti jumped out in front of me I hit my brakes and turn on my flashers.

Re: Brake lights in B mode

Posted: Fri Feb 10, 2017 5:53 am
by arnis
There are multiple ways to show brake force.
BMW uses 2-4 different ways in combinations (depends on model)
https://www.youtube.com/watch?v=cV8ClIxuF3o
https://www.youtube.com/watch?v=gSiLDY-abRU

a) Rear FOG lamp (or 2 lamps for german vehicles) is used in addition to 3 regular brake lights.
b) Central brake light will blink while others are on steadily
c) all brake lights will blink
d) all brake lights will blink and rear fog lamps also activate
e) all brake lights blink and hazards switch on if extreme speed decrease is detected (incl standstill)
f) all lights (including fogs) blink rapidly
g) I've seen some Asian vehicles that blink hazards few times and nothing else happens.

Leaf could do everything except f (as fog light is halogen it will not be able to blink rapidly) but it doesn't.

Re: Brake lights in B mode

Posted: Sun Feb 19, 2017 4:22 pm
by estomax
i'm very surprised that in B mode there is no brake light, even at 25-30kw the brakes tug enough that in normal economical driving I only use the brake pedal to come to a complete stop at a stop sign or a red light. I assumed that my brake lights were coming on when regen was high until now. good to know.

Re: Brake lights in B mode

Posted: Sun Feb 19, 2017 10:06 pm
by DarthPuppy
LeftieBiker wrote:How is it different from driving a standard shift car in one of the low gears, and taking your foot off the gas...?
It isn't, but that can be unsafe too. The main question in this thread is regarding whether it is safe or could be made safer.

My father in law has been rear-ended twice. Each time, he was driving a manual transmission and using the engine brake to slow down considerably before applying the brakes to finish the stop. Both times were night time.

Yes, it is legal to do. Yes, it is technically the fault of the driver behind. But this driving does indeed increase the risk.

Too many drivers don't pay attention past the brake lights of the car immediately in front. So they don't notice the car stopping until the front car has already reduced speed and the distance has closed and then applied brakes for stopping. The driver in back no longer has the room to react and make up the speed differential. Bam!

I choose to avoid unneeded risk when reasonably foreseeable. Yes, I or my heirs could win the lawsuit, but getting rear ended is not worth it. I don't like the idea of being dead right or crippled right.

As such, while I like to use the B mode, I refrain from doing so in thicker traffic or when someone is relatively close behind me, especially at night. The marginal gains in efficiency aren't worth the risk in my assessment.

I'm really surprised given how much in automobiles are regulated by the Feds that there isn't some sort of standard on this aspect. As noted above, at least one company decided that safety warranted activating the brake lights. But also as noted above, constant brake lights could also increase the risk as there would no longer be contrast between moderated speed and actually stopping hard. I can see that the car companies are at high risk for lawsuits regardless of what they do in this area until there is a regulation that allows the "we followed the government rules and had to do it this way" defense.

Interesting points. For manuals, that arose out of old tech and probably simply hasn't been re-evaluated whether it makes sense to have the new-fangled computers turn on the brake lights when they perceive the driver is using the engine to slow the car. As EVs with this type of regenerative 'braking' become more common, I suspect we will eventually see a rise in cases where this was a factor. Probably after that is noticed statistically, then the companies or the Feds will act on it.

But good question and discussion. Hopefully the companies/Feds read these types of boards and will start looking into this aspect. I suspect the computers can be programmed to recognize when the car is slowing down regardless of what is causing it (e.g., brakes, manual transmission use, starting up a hill, etc.) and turn on the brake lights once a certain threshold is reached. This should avoid the scenario of down-hill use to moderate speed leaving the brake lights on and thereby losing contrast versus when the car actually does start to stop. Also, perhaps the flashing light solution mentioned above could help.

Re: Brake lights in B mode

Posted: Mon Feb 20, 2017 2:22 am
by arnis
Millions of miles traveled with Leafs suggest that Nissan Leaf brake light behavior is better than average.

Re: Brake lights in B mode

Posted: Mon Feb 20, 2017 5:32 am
by redLEAF
RonDawg wrote:FWIW the VW eGolf's brake lights do come on if the needle on the power/regen gauge reaches the first white mark on the regen side. I don't know of other plug-in cars do that.

Image
+1 -- love this feature on my e-Golf as well; tells tailgaters to back off; apparently BMW's i3 does as well (see link below); I did my own unscientific test by driving on a dark road at night and seeing where the threshold is (easy to see 3rd brake light illuminating in the back hatch window)

http://insideevs.com/bmw-i3-regenerativ ... est-video/

Tesla's do as well so I did a bit of digging and actually (of course) there is a set of guidelines on this whole thing that is recommended; has to do with how fast the car decelerates, etc. Tesla has a replica of the car on the center display in front of the driver where you can see when your car has the brake lights on (along with headlights, etc.).

Here is a link on the guidelines ... this is indeed a safety issue, not unlike following someone who simply has NO brake lights working

http://www.unece.org/fileadmin/DAM/tran ... 13hr2e.pdf