Brake lights problem: not working above 136 km/h under regen

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Brake lights problem: not working above 136 km/h under regen

von slcuervo » 8. Dez 2015, 22:37

Hello all,

This is my first post in this forum, so let me begin by saying that I am not German and not living in Germany. However, I sometimes drive in Germany with my Model S, and there is something I would like to ask to the owners of a Tesla Model S in Germany.

On my most recent trip, I have found out something that is still puzzling me today: the brake lights do not go on when decelerating with full regenerative braking (60 kW +) if your speed is above 136 km/h.

I have posted a blog entry about this issue, you can find it here: http://teslaroadtripeurope.blogspot.no/2015/12/brake-lights-problem-with-regenerative.html

It includes a video where I explain it with further details.

What do you guys think?
 
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Re: Brake lights problem: not working above 136 km/h under r

von volker » 8. Dez 2015, 23:15

We discussed this topic just a few days ago here:
viewtopic.php?f=58&t=8532&p=196279&hilit=136#p196279

Consensus is, this is an intended effect of Tesla's algorithm to drive the brake lights depending on deceleration. If road conditions allow for full 60kW recuperation power, the deceleration is 0.7m/s² at 136km/h which appears to be the threshold value to trigger the brake lights. With decreasing speed, a constant recuperation power means increasing deceleration.

Spürmeise hat geschrieben:Wie hoch ist die Verzögerung bei 136 km/h, wenn die Bremsleuchten einsetzen?
Code: Alles auswählen
P = F * v
P = m * a * v
a = P [W] / (m [kg] * v [m/s])
a = 60000 kg m²/s³ / (2200 kg * 37,8 m/s) = 0,72 m/s² oder ca. 0,074g

(Luft- und Fahrwiderstände unberücksichtigt)
Autos und Häuser brauchen keinen Auspuff.
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Re: Brake lights problem: not working above 136 km/h under r

von slcuervo » 9. Dez 2015, 10:00

Thanks for the reply.

Have you discussed the different behavior between AP cars and non AP?
 
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Re: Brake lights problem: not working above 136 km/h under r

von Talkredius » 12. Dez 2015, 22:47

one additonal comment :

depending on the design of the motor/inverter combination the motor runs with constant torque from 0... x km/h (x= base frequence)
faster than x with contant power, the torque will be reduced by ~1/speed
The torque is proportional to the acceleration/deceleration. To my knowledge this has nothing to do with AP or non AP.

With standard electric motors this base frequency is 50 Hz star connected or 87 Hz delta connected with a 50 Hz grid, 60 Hz / 104 Hz with a 60 grid, eg. US, Japan etc.
With a special motor/inverter combination like in the Model S you may design any base frequency you like.

More details (in english) you'll find here, page 26 ff :
http://download.sew-eurodrive.com/downl ... 522913.pdf
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