Sorry couldn't find a recent answer. Do they always come on or just with big speed changes? Will it appear as if we are super brake pedal happy?
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Will it appear as if we are super brake pedal happy?
They turn on when you reach a certain deceleration level (roughly half), and they also turn on immediately if you lift off the pedal quickly.
If you just lift a little they do not turn on.
It might be an accelerometer, but more likely they're using power from the motor (or a corresponding control system variable) to determine deceleration.
Jerry33 said:We know that it's based on "braking force" and not just when you touch the brake pedal because it comes on when you use regenerative braking hard enough.
It has to be smarter than just accelerometer / deceleration: Imagine a steep downhill where there's significant regen required to keep the car at a constant speed. I'm pretty sure the brake lights are on in this condition.
I've heard a number of times from different Tesla employees that it uses an accelerometer for this...but as we know, that doesn't necessarily mean it's true.
In that case, the car is pitched down and even though its speed may be constant, the gravity vector has enough forward component that the accelerometer would register an apparent braking force...lighting the brake lights.
Curious to know if an accelerometer measures that?
I figured it only would "see" vector changes.
Still, how would it know the difference between 1 MPH downhill and 30 MPH downhill (the former would not light up the brakes)? I'm still convinced it's more complex than just an accelerometer (this is based on my observations in my Roadster; obviously may be different in Model S, but probably MORE advanced).
Standing still on the earth we're at 1G of acceleration downward...the necessary centripetal acceleration to continue moving in an (approximate) circle as the earth rotates. So while we are apparently not accelerating from our own point of view, if viewed from space we in fact are. Accelerometers will measure that centripetal acceleration. (By the way, these are the kinds of initial thoughts that spurred Einstein's Theory of Relativity).
It has to be smarter than just accelerometer / deceleration: Imagine a steep downhill where there's significant regen required to keep the car at a constant speed. I'm pretty sure the brake lights are on in this condition.
Why would you want them to be on ? In an ICE car I just downshift to the appropriate gear for the downhill, and the brake lights never come on unless it is so steep that I have to brake occasionally. If I have to, I brake hard and for a short time so the brakes can cool off in between. People who have their brake lights on all the time coming down a mountain pass come off like driving amateurs and their brakes end up smoking hot and sometimes failing.
I certainly don't want my brake lights being on when keeping constant speed on a steep downhill.