BMW i3 Brake Light Test - Regenerative Braking

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dvottero

Member
Joined
Feb 16, 2014
Messages
22
Location
Los Angeles, CA
My favorite feature of the BMW i3 is one pedal driving. But ever since my first drive in November 2013 — I never had a good sense of what causes the brake light to trigger, and when. A month behind the wheel didn't answer this either. So I did what any normal person would do: I strapped (4) GoPros to my car and filmed a quick drive around town to answer my question:

https://www.youtube.com/watch?v=JXJPf7Lv8Sw

My conclusion is that the brake light activates perfectly in all the driving conditions I tested— and as a general rule — triggers when the regen meter moves past the word "Charge."

The video I made is a split screen test that shows the dash, forward view, pedals and brake lights on an i3 REX on all EV driving in Los Angeles, CA. The car was in Comfort mode for the entire test and was driven for "fun" — and not range.
 
Nice test, thank you! Good to know that the lights don`t activate when regen is only slight. Was wondering about that.

Frank
 
This is great information. One observation: it appears that when the car is stopped, say, at a traffic light and the brake pedal is not depressed, the brake lights are off. Since the car is designed with no "idle creep", this is somewhat at odds with how other cars work. Even in my F10, "auto hold" when active holds the brake lights on at a stop. BMW should rethink this. Illuminated brake lights on a stopped car represent a safety advantage.
 
I never use hill hold on my car because there's nothing wrong with my handbrake or my co-ordination!

In an era of high level brake lights, which often seem to be of much higher intensity if they are LEDs and/or fibre optics, I wish to show consideration to whoever is behind me by not dazzling them, especially at night. Far from being an aid to safety, brake lights on a stationary car are an irritation and a safety hazard.

https://www.gov.uk/general-rules-all-drivers-riders-103-to-158/lighting-requirements-113-to-116 said:
114
You MUST NOT

use any lights in a way which would dazzle or cause discomfort to other road users, including pedestrians, cyclists and horse riders
use front or rear fog lights unless visibility is seriously reduced. You MUST switch them off when visibility improves to avoid dazzling other road users (see Rule 226).

In stationary queues of traffic, drivers should apply the parking brake and, once the following traffic has stopped, take their foot off the footbrake to deactivate the vehicle brake lights. This will minimise glare to road users behind until the traffic moves again.
Law RVLR reg 27
 
raleedy said:
BMW should rethink this. Illuminated brake lights on a stopped car represent a safety advantage.

Simple solution: Press the brake pedal after regen brings the car to a stop. Brake lights will be on and the car will be secured against rolling.
 
RJSATLBA said:
I never use hill hold on my car because there's nothing wrong with my handbrake or my co-ordination!

In an era of high level brake lights, which often seem to be of much higher intensity if they are LEDs and/or fibre optics, I wish to show consideration to whoever is behind me by not dazzling them, especially at night. Far from being an aid to safety, brake lights on a stationary car are an irritation and a safety hazard.

https://www.gov.uk/general-rules-all-drivers-riders-103-to-158/lighting-requirements-113-to-116 said:
114
You MUST NOT

use any lights in a way which would dazzle or cause discomfort to other road users, including pedestrians, cyclists and horse riders
use front or rear fog lights unless visibility is seriously reduced. You MUST switch them off when visibility improves to avoid dazzling other road users (see Rule 226).

In stationary queues of traffic, drivers should apply the parking brake and, once the following traffic has stopped, take their foot off the footbrake to deactivate the vehicle brake lights. This will minimise glare to road users behind until the traffic moves again.
Law RVLR reg 27

What a rare and stunning concentration of rot. Hill hold and Auto Hold are completely different concepts. You can look it up. Until you do, permit me to remain skeptical about the level of your foot coordination skills. I think it's clear enough that there is nothing about the language of your motoring rules that would prevent a driver from holding the car stopped with a foot brake, as nearly everyone nearly always does, and nothing about the intensity of a modern production car's brake lights that would represent a source of infraction of the mentioned rule. BMW's Auto Hold function, which substitutes for applying the parking brake in the situations you describe, keeps the brake lights on. The attention called to the stationary car by the illuminated brake lights is without question a contribution to safety.
 
Children children.

I think the quoted regulation is the law of the land.

In addition if you keep your foot on the footbrake and do not apply the hand brake on your driving test you will fail and not be awarded a licence. That is not "rot" just the way it is.

I am sure it is different in the US. EDIT. I expect this is normal practice on an automatic but not on a stick shift which I think the OP is referring to his skills at.

I must say I like the auto handbrake function on my F10 too. I wasn't aware that it kept the rear lights on. That is interesting. Will need to test that. Pity the i3 doesn't seem to have this function.
 
It's really simple. If you are at the back of a stationary queue of traffic, use the foot brake to hold the car so that the brake lights are on. If someone stops behind you swap to the handbrake so that the brake lights are no longer on. Do this to avoid dazzling the driver behind but also because the brake lights are no longer needed as a safety measure because you are no longer at the back of the queue. Continue to use the handbrake for any prolonged stops until you are at the back again and then switch to using the foot brake. Same deal as rear fogs, put them on when at the back of a queue when no one is behind you then switch them off once your back is covered by another car.

Bill
 
Awesome! I was wondering about that. We were thinking about how annoying it must be to constantly see the brake lights on. "Over-aggressive breaker syndrome." But, that is great that it does show them but not all the time. Great job with the video! Thanks for sharing! :)
 
Hi,
I had the same issue. Wanted to see in first person when do they get on.

Today I've prepared a low tech temporary patch to see it myself:
https://twitter.com/powneronline/status/806838037174947840?s=09

They should make it to be indicated in the instruments panel, somehow....

http://productowner.online/2016/05/22/bmw-i3-one-pedal-feeling/
 
Nice trick! Thanks.
However, I would advise against using any tape (like duct tape) that can bake in the sun and cause severe residue problems, especially on plastics; I used 3M blue tape.
I grew up on a stick, have always used engine braking, and consider actually having to hit the brakes too early as a mark of failure to read the road ahead, so I am quite dismayed to find out how wussy-sensitive the i3 regenerative bake light is. To my mind it enters the realm of Too Much Information, flashing on and off when I feel all I am doing is coasting down—not actually braking—and sending the signal to those behind me that I am a timid driver with my foot constantly fluttering over the brake.
 
i3an said:
I grew up on a stick, have always used engine braking, and consider actually having to hit the brakes too early as a mark of failure to read the road ahead, so I am quite dismayed to find out how wussy-sensitive the i3 regenerative bake light is. To my mind it enters the realm of Too Much Information, flashing on and off when I feel all I am doing is coasting down—not actually braking—and sending the signal to those behind me that I am a timid driver with my foot constantly fluttering over the brake.
These days with so many drivers paying more attention to their smart phones than to driving, I'm happy to have our i3's brake lights illuminate aggressively in hopes that maybe the following driver will notice them and actually start decelerating.
 
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