Do brake lights always turn on with regen? (incl gap to other cars)

[Doug_G]

I think it is unsafe for the car to light up the brake lights if all you are doing is holding steady speed downhill. If you then suddenly mash on the brakes, no additional lights are show to indicate you started to slow down, and you risk getting hit from behind.

How is this different from an automatic ICE? Many drivers simply use the brakes to control their speed on a long downhill. Of course it's better to kick the transmission down but many drivers don't do that. So their brake lights are on for extended periods of time.

 

[jkirkebo]

How is this different from an automatic ICE? Many drivers simply use the brakes to control their speed on a long downhill. Of course it's better to kick the transmission down but many drivers don't do that. So their brake lights are on for extended periods of time.

Riding brakes is also unsafe. Done over a long time, the brakes will overheat and fade. We also have a VW TDI with the DSG gearbox, I always downshift on long downhills. If for example 3rd is a bit too high and 2nd is too low, I will let the car gain some speed in 3rd, then downshift to 2nd to bleed off some, then back to 3rd. If I'm braking (like before tights turns) it is hard and briefly.

 

[jerry33]

How is this different from an automatic ICE? Many drivers simply use the brakes to control their speed on a long downhill. Of course it's better to kick the transmission down but many drivers don't do that. So their brake lights are on for extended periods of time.

Many drivers still believe in the myth that using lower gears will wear out either the transmission, the engine, or both. I always wonder why they aren't afraid to drive forward for fear of wearing out these parts. They always fall back on the "brakes are cheap to replace and designed to wear out" argument.

 

[contaygious]

So true. I know mechanics that don't like driving down big hills for fear of messing with their transmission. Most people don't even think to downshift and just brake all the time. Hopefully when everyone converts to EV then we will all regen!

 

[jerry33]

So true. I know mechanics that don't like driving down big hills for fear of messing with their transmission. Most people don't even think to downshift and just brake all the time. Hopefully when everyone converts to EV then we will all regen!

One of the things driving a Land Rover Series III or earlier teaches you is "You don't use the brakes unless it's absolutely necessary". If you've ever watched the movie The Gods Must Be Crazy you'll learn that the screenwriters had first-hand familiarity with them.

 

[Doug_G]

One of the things driving a Land Rover Series III or earlier teaches you is "You don't use the brakes unless it's absolutely necessary". If you've ever watched the movie The Gods Must Be Crazy you'll learn that the screenwriters had first-hand familiarity with them.

:biggrin: "Don't worry! It'll come back!" "What???"

 

[jkirkebo]

One of the things driving a Land Rover Series III or earlier teaches you is "You don't use the brakes unless it's absolutely necessary". If you've ever watched the movie The Gods Must Be Crazy you'll learn that the screenwriters had first-hand familiarity with them.

I can say that this also holds true for a '87 VW Jetta 1.8

 

[wycolo]

> the second I take my foot off the accelerator and regen starts, the brake lights go on, even at high (coasting) speeds on the highway. I noticed cars behind me getting slightly annoyed, but I didn't mind because it keeps them from tailgating, I guess.

Another goofball who rides the brake pedal. I'm tempted to switch that wire over to the ambers. Assuming *that* wire can be isolated from the rest of the red feeds.
--

 

[sublimaze1]

> the second I take my foot off the accelerator and regen starts, the brake lights go on, even at high (coasting) speeds on the highway. I noticed cars behind me getting slightly annoyed, but I didn't mind because it keeps them from tailgating, I guess.

Another goofball who rides the brake pedal. I'm tempted to switch that wire over to the ambers. Assuming *that* wire can be isolated from the rest of the red feeds.
--

Does that get lessened if you decrease the setting on the regen? Or can you not?

 

[Zextraterrestrial]

> the second I take my foot off the accelerator and regen starts, the brake lights go on, even at high (coasting) speeds on the highway. I noticed cars behind me getting slightly annoyed, but I didn't mind because it keeps them from tailgating, I guess.

Another goofball who rides the brake pedal. I'm tempted to switch that wire over to the ambers. Assuming *that* wire can be isolated from the rest of the red feeds.
--

Tesla really needs to lower the sensitivity of the regen/ make it adjustable. I find it unacceptable for the lights to come on under regen deceleration of the S, even full regen at slower speeds (which isn't that strong due to the cars weight IMO).

 

[aviators99]

Tesla really needs to lower the sensitivity of the regen/ make it adjustable. I find it unacceptable for the lights to come on under regen deceleration of the S, even full regen at slower speeds (which isn't that strong due to the cars weight IMO).

It is based on the Rearward G-force, so if it's done correctly, they should turn on at the same level as a normal car without regen when you use the brakes.

 

[hcsharp]

Another goofball who rides the brake pedal. I'm tempted to switch that wire over to the ambers. Assuming *that* wire can be isolated from the rest of the red feeds.
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Much more complicated than that. The brake light actuator takes input from multiple sources including an accelerometer, speed, power or rate of regen and more. This has been discussed at length wrt the Roadster and the software was tweaked a few times.

 

[pete8314]

Much more complicated than that. The brake light actuator takes input from multiple sources including an accelerometer, speed, power or rate of regen and more. This has been discussed at length wrt the Roadster and the software was tweaked a few times.

This probably needs a new thread, so mods, feel free to move this...

I agree that having the brake lights come on as soon as you lift the accelerator pedal is weird. Nothing (well, almost nothing) annoys me more than people dabbing the brakes at speed when it's completely unnecessary.

Back in the day, I used to have an Astra GTE (manual/stick) that had an LCD dash (ooooh!), and a few lights to check various functions, including brake lights. The warning light would stay lit until the first brake, where it would acknowledge the lights were working, and extinguish. My big challenge every day was to get to the office without braking (~10 miles, light traffic), and I used to manage it every now and then. My point being, the regen is generally 'sold' as being a bit like a manual, when if you drop a gear, the car will slow. In that case, the brake lights don't come on, and people behind don't get stressed by it. I'm sure the logic for the Model S is complicated, and I've no idea how a Volt (for example) does it, but the current set up seems flawed. If I know that I 'brake' as soon as I lift off, I'll be overly-conscious of managing the accelerator pedal, which is a little distracting.

Of course, I say all of this based on this thread and a couple of test drives, so actual owners may have a more relevant point of view.

 

[weccman]

> the second I take my foot off the accelerator and regen starts, the brake lights go on, even at high (coasting) speeds on the highway. I noticed cars behind me getting slightly annoyed, but I didn't mind because it keeps them from tailgating, I guess.

Another goofball who rides the brake pedal. I'm tempted to switch that wire over to the ambers. Assuming *that* wire can be isolated from the rest of the red feeds.
--

I would not do this. I love the regen and I'm glad that the drivers behind me are warned when my vehicle will start slowing down. In two weeks, I have gotten so used to simply squeezing off the accelerator slowly so that there is minimal "down-shifting-like" jerkiness that you get if you just treat the vehicle like an ICE car, that I normally don't even apply the brakes until we are going about 7 mph. If folks are unhappy that my brake lights come on when I start to decelerate, I don't care. We'd all be much worse off if they did not come on and they rear-ended my car not realizing I was slowing down.

 

[v12 to 12v]

> the second I take my foot off the accelerator and regen starts, the brake lights go on, even at high (coasting) speeds on the highway. I noticed cars behind me getting slightly annoyed, but I didn't mind because it keeps them from tailgating, I guess.

Another goofball who rides the brake pedal. I'm tempted to switch that wire over to the ambers. Assuming *that* wire can be isolated from the rest of the red feeds.
--

You are right. This is unnerving. In some areas at night on a winding or hilly road, any hint of brake lights means immediate action is necessary. i.e. Both feet in, standing on the brake and clutch, because a solid immovable object or a massive animal is on the road. :scared:
I hope a sensitivity adjustment on the update list.

 

[weccman]

You are right. This is unnerving. In some areas at night on a winding or hilly road, any hint of brake lights means immediate action is necessary. i.e. Both feet in, standing on the brake and clutch, because a solid immovable object or a massive animal is on the road. :scared:
I hope a sensitivity adjustment on the update list.

Maybe if people just backed off a bit and allowed a car length for every 10 mph as we were taught in driver training, this would not pose such a problem. Okay, I guess I am being unreasonable again. That won't happen. But it sure is a better option to not giving warning when the car will be slowing as it does during regen.

 

[v12 to 12v]

Maybe if people just backed off a bit and allowed a car length for every 10 mph as we were taught in driver training, this would not pose such a problem. Okay, I guess I am being unreasonable again. That won't happen. But it sure is a better option to not giving warning when the car will be slowing as it does during regen.

I guess the thinking is different when you don't have to deal with a herd of elk leaping onto a highway at night. Sometimes a huge following distance isn't enough on a rural highway and you have to trust the brake lights down the road to advise you of the situation. I always hang way, way back on those roads and I know that brake light without a turn signal means something is seriously wrong. I still have had some close calls, especially this time of year. I don't follow close enough for there to be a need for a brake light during regen.

 

[aviators99]

You are right. This is unnerving. In some areas at night on a winding or hilly road, any hint of brake lights means immediate action is necessary. i.e. Both feet in, standing on the brake and clutch, because a solid immovable object or a massive animal is on the road. :scared:
I hope a sensitivity adjustment on the update list.

In a "normal car", if you press the brake lightly, the brake light will come on. In the Model S, if you take your foot completely off the accelerator, the physics of the car are the same as if you touch the brake on a normal car, so therefore the brake lights come on. It's the same.

 

[strider]

The Roadster also takes into account the "rate" at which you let off the accelerator. If you jump off the pedal the brake lights will fire immediately as the assumption is that you want to slow quickly and others should be warned of this. If you ease off but still go to full regen the lights will not come on until you're near full regen (depending on the other factors like hcsharp noted). As you get used to the car you won't be jumping on and off the accelerator as quickly and this behavior will smooth out.

- - - Updated - - -

You are right. This is unnerving. In some areas at night on a winding or hilly road, any hint of brake lights means immediate action is necessary. i.e. Both feet in, standing on the brake and clutch, because a solid immovable object or a massive animal is on the road. :scared:
I hope a sensitivity adjustment on the update list.

You obviously have a higher class of idiot drivers where you live. Around here cars ride their brakes all the way down hills and brake before every curve in the road. This renders their brake lights useless for anyone behind them. I like that my Roadster lights the brake lights on regen as the car slows more quickly than downshifting my Corvette - some warning is required. I don't have my S yet so have to see if my thoughts change.

 

[Doug_G]

The Roadster doesn't turn on the brake lights unless you (a) go to about 1/2 regen power, or (b) lift off the pedal quickly. A light throttle lift doesn't do it. Can you check how much of a lift is required before the Model S lights up?

(Also probably this discussion should be broken out from the Delivery Update thread.)