Revelations From a Visible Brake Light
- Thread starter insightman
- Start date
- Replies 110
- Views 26K
Texas22Step
Well-Known Member
Yep. Same for me, even though I have barely learned to "stop" the vehicle using regen. While I will still try to use the regen (single pedal driving), we will all use the brake pedal once stopped to be sure that the brake lights are illuminated for traffic behind us.
Since with the ICE cars people normally lift their foot from the throttle before stepping on the brake. I think it would be an easy software fix to program the brake light to illuminate once the throttle paddle senses that the foot is off or it returns to its resting position.
The test car I drove the other day still roll gently even though the display said "0", so it is normal for me to press on the brake paddle while stopped.
The test car I drove the other day still roll gently even though the display said "0", so it is normal for me to press on the brake paddle while stopped.
The brake light DOES illuminate when I remove my foot from the throttle pedal. However, after regen braking brings the car to a stop, the brake lights go out (and, as you noted, the car can roll forward if there is a slight downhill--but there is no "creep" like ICE-cars with automatic transmissions have).
The brake lights goes out even when I remove my foot from the brake pedal while facing uphill and the SE is preventing itself from rolling backwards. Does that mean it's the motor, not the brakes that is preventing the car from rolling backwards?
Conversely, when you're backing up a hill, the SE won't let you roll forwards after removing your foot from the accelerator pedal.
I guarantee the operation of the SE's regen braking and brake light is exactly the way BMW/MINI (and their lawyers) intended. So no software patch will be forthcoming.
Puppethead
Well-Known Member
My experience would say yes, once the SE comes to a stop from the regenerative braking, the motor is providing friction to keep it from rolling in the wrong direction but the correct direction is "free", meaning the SE can be pushed or will roll on the slightest incline. The friction brakes do not seem engaged unless the brake pedal is depressed (or traction control is doing its thing, which wouldn't happen at rest).
Since the brake pedal is a "fly-by-wire" control – meaning it's not physically connected to the brake lines, but simply sends signals to the brake system – there could possibly be a software hack. But I don't think hacking the brakes is the first thing I'd mess around with...
Since the brake pedal is a "fly-by-wire" control – meaning it's not physically connected to the brake lines, but simply sends signals to the brake system – there could possibly be a software hack. But I don't think hacking the brakes is the first thing I'd mess around with...
Wait, we know from this thread that when the SE's electric vacuum pump failed on @dmaxwell, "The brake pedal felt hard and the brakes did very little." So the brakes stopped being power brakes, but didn't go away completely. Doesn't that indicate the SE is conventionally "brake-by-fluid," rather than "brake-by-wire?"
Puppethead
Well-Known Member
Good point, maybe I'm completely wrong? I swear someone told me that but I can't remember from where. Or possibly there's sophisticated two-way sensing? I retract my comment, apologies.
I know it’s been a year but, I wanted to give this a try and was gonna order the 50, do you still have some?I was frustrated by not knowing when my MINI Cooper SE was autonomously illuminating its brake lights in response to regenerative braking. Rather than tape a piece of aluminum foil to the hatch to reflect the high-mounted, center brake light into the hatch window, I wired an LED in parallel with the center brake light and mounted it where I could see it in the rear-view mirror. I have put an illustrated step-by-step description of my modification online.
After my visible brake light was operational, I was disappointed to discover how little regenerative braking is required to illuminate the brake lights. Regardless of whether I choose High-Energy Recovery or Low-Energy Recovery regenerative braking, I found the brake lights flash on and off frequently as I drive. I am using the indicator LED to train myself to know instinctively when I'm displaying brake lights to the car behind me.
Some tail-gating drivers see my MINI Cooper SE's display of brake lights as an aggressive driver-instigated signal to back off. Other drivers probably assume I'm carelessly driving with my left foot on the brake pedal. My goal is to prevent the brake lights from flashing on
and off in short, random-seeming bursts.
The most surprising and disturbing behavior I noted was that the brake lights go dark after the regenerative braking brings the MINI Cooper SE to a complete stop. So if you want to be sure the driver of the car coming up behind you realizes you are stopped, remember to use the brake pedal to illuminate the brake lights.
I wish the MINI engineers could have developed an artificial intelligence that would illuminate the brake lights more appropriately. Evidently, MINI's lawyers deemed even the level of deceleration typically provided by engine-braking in a gas-powered MINI to be dangerous without illuminating the brake lights of this electric vehicle. Where were those lawyers when it was decided a stopped MINI Cooper SE would not always illuminate its brake lights?
BTW, I have 48 of these LEDs left over because I had to buy 50 on Amazon.com. Anyone who wants a couple can PM me and I'll send them free of charge.
Fortunately, the box of 49 LEDs just popped up in my basement. PM me your address and I'll send you a couple.
Puppethead
Well-Known Member
I was wondering just this morning about how often the brake lights are triggered using cruise control, and thought of @insightman's LED mod. Since the regenerative braking happens when the driver eases back on the "go" pedal, does cruise control speed control trigger brake lights at any time?
The other thing that came to mind recently is I don't see a lot of brake lights activating on Teslas. Do they never slow down, or maybe Teslas don't do regen (doubtful) or just not bother alerting other drivers when slowing?
The other thing that came to mind recently is I don't see a lot of brake lights activating on Teslas. Do they never slow down, or maybe Teslas don't do regen (doubtful) or just not bother alerting other drivers when slowing?
Haha Teslas do slow down and they do have regen braking, their brake lights come on depending how fast they let go of the go pedal. If you let go quickly brake lights come on, they do stay on when you let go completely. If they let go slowly and coasting, it doesn’t come on until a certain point
With my 2021 SE, the brake lights come on when the instrument panel's power/charge needle touches the first regen block. I would be surprised if the 2022 behaves any differently under its adaptive cruise control.
Puppethead
Well-Known Member
Mine's a 2021 without adaptive cruise control and it has to adjust speed for hills, so even it should be doing some slowing down. Or, like I had to this morning, one accelerates past a badly-merging yahoo without disengaging cruise control, and letting the car resume preset speed.
GvilleGuy
Well-Known Member
I covered this in my ACC video. On the 2022, as soon as the needle touches the first regen block, brake lights are on with cruise control. But cruise does a better job than I do of keeping the car in the 'ready' zone at speed so that the brake lights are not on.
ghost
Well-Known Member
I'm bumping this thread bc we're having a conversation about it on the UK forum, and this thread was linked over there.
Just having bought my OBD2 adapter and bimmercode, I've tried changing the brake force display settings from weak (5 m/s^2) to medium (7). The result was the brake lights still flashed as soon as I let off the accelerator, even at speeds under 25 mph, and using low gen.
Next time, I'm going to change the setting to heavy (8 m/s^2) to see if that makes any difference.
Doesn't solve the brake lights activating at full stop issue, but I don't like heavy regen unless I'm going downhill.
Even in my wife's Tesla, we set it to "roll", after reading about the costly periodic rotor resurfacing from never needing the mechanical brakes (Tesla regen is high by default).
Just having bought my OBD2 adapter and bimmercode, I've tried changing the brake force display settings from weak (5 m/s^2) to medium (7). The result was the brake lights still flashed as soon as I let off the accelerator, even at speeds under 25 mph, and using low gen.
Next time, I'm going to change the setting to heavy (8 m/s^2) to see if that makes any difference.
Doesn't solve the brake lights activating at full stop issue, but I don't like heavy regen unless I'm going downhill.
Even in my wife's Tesla, we set it to "roll", after reading about the costly periodic rotor resurfacing from never needing the mechanical brakes (Tesla regen is high by default).
Puppethead
Well-Known Member
I don't think that's as much of a concern in the SE since I believe the traction control uses the friction brakes (because it's the same traction control as the ICE models). Although I'm not entirely sure that's how it works.
Carsten Haase
Well-Known Member
One pedal driving will also use the friction brakes instead of regen when the car is close to 100% battery
DialCottageInWales
New Member
Hi folks,I'm just jumping in here with this - don't mean to be rude!
There are regulations for when brake lights should turn on.
The regulations for the UK state that if the deceleration is
I've been following a different ev forum for a few years. People there were trying to use changes in speed, and the time it took to make that change as a way of checking their rate of deceleration. I knew that most phones and tablets had good accelerometers in them, so I thought I'd try to find an app that would help. I couldn't find one though, but kept it in the back of my mind til now. I've written an app that should help. You can find it in your appstore from links on http://www.acceleration.wales
Full functionality for checking brake lights is completely free. I hope it's of some use.
There are regulations for when brake lights should turn on.
The regulations for the UK state that if the deceleration is
- less than or equal to 0.7 m/s/s the signal shall not be generated
- greater than 0.7 m/s/s and less than or equal to 1.3 m/s/s the signal may be generated
- greater than 1.3 m/s/s the signal shall be generated
I've been following a different ev forum for a few years. People there were trying to use changes in speed, and the time it took to make that change as a way of checking their rate of deceleration. I knew that most phones and tablets had good accelerometers in them, so I thought I'd try to find an app that would help. I couldn't find one though, but kept it in the back of my mind til now. I've written an app that should help. You can find it in your appstore from links on http://www.acceleration.wales
Full functionality for checking brake lights is completely free. I hope it's of some use.
ghost
Well-Known Member
After a couple of weeks, I realized that if I don't want to flash my brake lights, I'm just going to have to change my driving habits: stay on the accelerator longer and switch to high regen, stopping more abruptly (no more cruising to a gentle stop). This is the opposite of how I learned to drive an ICE vehicle.