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another regen/brake light discussion

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D.. We'd be on a hands-free cell phones, one behind the other, noting when lights come on in various circumstances. ..
It's not that hard to see the taillight come on yourself. Just adjust you mirror so you see the trunk lid. Even better at night.
Broken record me says that I don't like the light aways coming on and slowing down the freeway behind me.
 
I think that it works by measuring the regenerated power. When you're regenerating more than some number of kWs, the brake lights come on. This seems perfectly reasonable to me because it corresponds almost exactly to doing something that makes the brakes waste that much power. Whatever the number of kWs is, it is more than most cars get from engine braking, which is about the most deceleration the average driver is expecting without brake lights...
 
I was told that the brake light algorithm is a bit more complex. It triggers when you hit a certain deceleration (it's probably not a simple fixed threshold), and it also triggers if you lift off quickly. The precise algorithm is probably a trade secret. :wink:

One advantage of Fusion Red is that it's really easy to see when the brakes are on at night - just glance in the rear view mirror. Arctic White and other light colors are probably also good for that.

Having observed the behavior over time, I really like the way the brake lights work. Personally, I think they nailed it.
 
I think that it works by measuring the regenerated power. When you're regenerating more than some number of kWs, the brake lights come on. This seems perfectly reasonable to me because it corresponds almost exactly to doing something that makes the brakes waste that much power. Whatever the number of kWs is, it is more than most cars get from engine braking, which is about the most deceleration the average driver is expecting without brake lights...

The kW generated at 80 MPH (fully released accelerator pedal) is MUCH higher than at 10 MPH yet the braking force is much LOWER. Speed would have to taken into consideration.
 
Quite often when driving I will dab the brake pedal once or a few times when regening in traffic just to ensure that the car behind (often close behind in heavy motorway traffic) understands I am slowing.
You are a smart driver, Andrew!

Over the past 20 years of driving my manual transmission, I remember my car insurance company making a general recommendation that drivers avoid compression braking and instead use their brake pedal so that drivers behind will be alerted. You see, the insurance companies aren't worried about impeding the high-speed flow of freeway traffic, they're primarily concerned with preventing their customers from being rear-ended. It wasn't entirely comfortable, but I have made a point of using both feet when I want to ensure that other drivers won't make a mistake at my expense.

Someone pointed out that you can't flash the brake light with the brake pedal if the accelerator has already lit up the brake light. However, if you use both feet you can hold the accelerator steady enough that the brake light will not stay on, and then your brake pedal will control the brake light.

I guess it depends upon whether you assume that people behind you are better drivers or worse drivers. If you assume that they're worse, then you're safer giving them a few false alarms rather than have them plow into you because they don't slow down when you slow down. For those who are happy assuming that the drivers behind are better drivers than you are, then I can understand your complaint in that light.

Besides, we already have tons of drivers who use their brake pedal as a foot rest, and thus their brake light flickers like bad Christmas tree wiring. I think Roadsters are not nearly that annoying (but I haven't followed one yet).

By the way, Very Orange makes it easy to see the brake lights. As soon as I realized what was distracting me, I used the reflection to learn about the behavior of the brake lights. In my opinion, they work quite well.
 
BMW M5 and M6 have two stage brake lights. 1/3 or so come on for light braking, and they light up all at higher intensity when you really step on them. This idea could be incorporated into the Tesla easily giving the driver behind you an indication when you are slowing down, and an indication when you are braking.
 
You hate the light coming on, I am worried about them NOT coming on here in Europe. That's really a great problem and I would hate to have to use the brake just to tell the morrons behind me that I'm slowing down. The only hope is the people behind me will drive with more care, 'cause they are aware that hitting a so beautiful car would not be nice.
 
I don't have a copy of California's Motor Vehicle Code handy, but I belive that we motorists are obligated to signal, either by hand or by indicator lamp, when we are slowing the vehicle.
However, I cannot *ever* remember seeing anyone stick their arm out to indicate they are slowing/stopping, as everyone depends on the brake lights.

For the "brake lights on regen" issue, I expect that Tesla is following Federal laws requiring that the brake lamps must go on when the car is "braking," and Tesla is interpreting regenerative braking as "braking." Makes sense to me.

Since there *is* some "sweet spot" on the accelerator pedal that will engage regen (but not the brake lights), I guess it will just take a bit of practice to find out where it is.

There were (and may still be) motorcycle aftermarket kits that allowed the brake light to flash as the motorcycle slowed, and then changed to constantly on when below 20 mph or something. That was a life-saving feature for many riders, as it alerted the inattentive motorist behind them that the cycle was slowing down. Hmmm. I wonder if something like this could be adapted.

I will confess to, um, "more than once," driving an RX-7 at speeds that required three digits on the radar gun display, and downshifting into second gear to dump excess speed without illuminating the "I'M GUILTY" brake lights whilst zooming by. I guess that when I lose that clutch pedal, I'll lose that handy feature, though.

Ardie
 
There were (and may still be) motorcycle aftermarket kits that allowed the brake light to flash as the motorcycle slowed, and then changed to constantly on when below 20 mph or something. That was a life-saving feature for many riders, as it alerted the inattentive motorist behind them that the cycle was slowing down. Hmmm. I wonder if something like this could be adapted.
+1
Flashing the brake lights is a very important feature to keep in mind while discussing this topic. The human eye+brain is more affected by flashing lights than even just solid, bright lights. In situations where other drivers should be alerted to a potential situation, flashing lights would be preferred. Maybe the regen lighting should be solid so that it does not draw as much attention, but at the same time excessive g-forces should flash the brake lights for severe slowdowns.
 
The Hong Kong cars are close to European spec and come with the regen brake light disabled. You need to press the brake pedal for the brake light to come on.

Tetsous took this up with Tesla, as he was fed up with being tailgated while regen decelerating. Tesla agreed to turn it on for him, as the law in Hong Kong reads differently and doesn't seem to require the brake pedal to be pressed for a brake light to one on.

Last week, on request, Tesla turned mine on. The difference is remarkable. No more tailgating while decelerating. I guess it is a personal preference, but having seen the feature both enabled and disabled, I feel safer driving with it enabled.
 
I was told that the brake light algorithm is a bit more complex. It triggers when you hit a certain deceleration
This is what the salesman told me. He said it uses the car's accelerometer.

Having observed the behavior over time, I really like the way the brake lights work. Personally, I think they nailed it.
Since there's nothing I can do about it, I'm glad to see some folks like the way it works.

Meh. I was all worried it wasn't working like I'd wanted it to for a while, but then I learned to stop worrying and love the bomb.
Shaboom, shaboom!

(Anybody old enough to get SByer's reference should get mine too. :biggrin: )

By the way, Very Orange makes it easy to see the brake lights.
My color... if it ever comes...

As soon as I realized what was distracting me, I used the reflection to learn about the behavior of the brake lights. In my opinion, they work quite well.
Good! Another confirmation.

It's probably been suggested before, but the Roadster can measure G-forces so why not have the brake light light up when G-forces go over a threshold number.
That's what my salesman said it does.
 
Having observed the behavior over time, I really like the way the brake lights work. Personally, I think they nailed it.

I'd been reading this thread and paid specially close attention when I had the pleasure of following my wife driving our new Roadster from midtown Manhattan up the FDR and out to NJ on Friday night. I had never driven that route myself and was tailgating the Tesla as much as I dared to avoid missing the exits. The brake lights were just about ideal in my opinion. Maybe a bit *too* bright, brighter than any other car I could see, but better that than too dim. There were lots of instances where a slight slowdown was indicated in the brake lights before I could have noticed the spacing in the cars decreasing.
 
I will confess to, um, "more than once," driving an RX-7 at speeds that required three digits on the radar gun display, and downshifting into second gear to dump excess speed without illuminating the "I'M GUILTY" brake lights whilst zooming by. I guess that when I lose that clutch pedal, I'll lose that handy feature, though.
Any time your vehicle slows significantly, the front end lowers and the rear lifts. It's pure physics, and the only way to diminish the effect is a very tight suspension. This is another "I'm guilty" signal that Highway Patrol and other law enforcement are thoroughly trained to look for. For approaching traffic where the brake lights aren't visible, this is basically the only way to tell. What's more interesting is that it is a sure 'tell' no matter from what direction the offending vehicle is viewed.

In other words, the only way to avoid looking guilty is to gradually bleed off your excess speed without shifting the vehicle weight, and hope that you won't get caught before your speed falls within the allowed range. One convenient side effect of the Tesla Roadster algorithm is that if you gradually bleed off your excess speed in this manner then the brake light should not illuminate.

By the way: If you're an attentive driver then you'll be looking out for this effect on vehicles in front of you so that you can tell when they're slowing down even if their brake lights are not working.
 
As I understand it, radar guns are required to get several consistent readings in a row before they will display your speed. This ensures that they don't give you a ticket for some kind of glitch (interference, spurious reflection, etc.).

The practical upshot of this is: if you are decelerating hard the radar won't display anything. Under these conditions they simply won't get a reading on your speed, even if you are still well over the limit.