Pedal break issue

[Phillip L]

For the last week when I first drive my Model S 85 D the break pedal barely slows the car down. But the second and subsequent times it works normally. The weather has been about minus 5 or 6 degrees centigrade. This morning I was coming up to a traffic light and it turned amber, hit the breaks and no response, so I accelerated through the amber light. Tried the breaks just afterwards, worked fine. What gives?

 

[luckyj]

s/break/brake/g

 

[drklain]

If you initially depress the brake pedal, you are slowing down with regenerative braking (which may be limited based on battery state of charge and temperature). If regenerative braking is limited, you can see it on your dashboard display of energy utilization by a dashed yellow line in the lower part of the arc (indicating that part of regenerative braking is unavailable). If you depress the brake pedal further down, you activate the regular tire disc brakes which work just like any other car and will stop you just like any other car.

If you are depressing the pedal all the way down and the car isn't slamming to a stop because you just slammed on the brakes, something is wrong with your brake system and you need to get it in for service ASAP. From what you are describing, it doesn't sound like this is the case but rather you are not depressing the pedal down far enough to stop the car.

 

[ggr]

If you initially depress the brake pedal, you are slowing down with regenerative braking (which may be limited based on battery state of charge and temperature). If regenerative braking is limited, you can see it on your dashboard display of energy utilization by a dashed yellow line in the lower part of the arc (indicating that part of regenerative braking is unavailable). If you depress the brake pedal further down, you activate the regular tire disc brakes which work just like any other car and will stop you just like any other car.

If you are depressing the pedal all the way down and the car isn't slamming to a stop because you just slammed on the brakes, something is wrong with your brake system and you need to get it in for service ASAP. From what you are describing, it doesn't sound like this is the case but rather you are not depressing the pedal down far enough to stop the car.

That's not correct in a Tesla. All regeneration is done by the right pedal, and the left pedal controls only the brakes. Is it possible that there was a layer of ice on the disks? (That's a serious question... I haven't lived in that kind of environment.)

 

[Drlev]

Quite likely a layer of ice/moisture/rust on one of the brake components. First attempt at braking rubs it away.

 

[sakimano]

Quite likely a layer of ice/moisture/rust on one of the brake components. First attempt at braking rubs it away.

yup

driving on a highway in a snow storm on saturday, and when I exited my brakes were barely effective at all in stopping the car. A layer of moisture had built up and iced over. Giving the pedal a good push while at speed will clear that, which isn't ideal when you're trying to exit a highway. Fortunately regen braking took care of most of the slowing down.

My previous car, an Audi RS4, had a feature that would barely initiate the calipers on the brakes every 20 seconds or so if it sensed moisture on the rotors. Not enough to have you feel it, just enough to get the moisture off. Brilliant little piece of programming. Would be nice if Tesla initiated the same.

 

[drklain]

That's not correct in a Tesla. All regeneration is done by the right pedal, and the left pedal controls only the brakes. Is it possible that there was a layer of ice on the disks? (That's a serious question... I haven't lived in that kind of environment.)

Interesting. My understanding was that if you put regenerative braking setting to "low" instead of "full" (or whatever the setting is on the settings page) OR if you have creep mode set to on, that you did not get full regenerative braking by full release of the "throttle" pedal and needed to depress the brake pedal to get it. It was explained to me to being similar to what the regenerative braking modes were on a hybrid, but I honestly never looked closely, so I'm happy to be told I'm wrong and learn something new.

 

[trace]

yup

driving on a highway in a snow storm on saturday, and when I exited my brakes were barely effective at all in stopping the car. A layer of moisture had built up and iced over. Giving the pedal a good push while at speed will clear that, which isn't ideal when you're trying to exit a highway. Fortunately regen braking took care of most of the slowing down.

My previous car, an Audi RS4, had a feature that would barely initiate the calipers on the brakes every 20 seconds or so if it sensed moisture on the rotors. Not enough to have you feel it, just enough to get the moisture off. Brilliant little piece of programming. Would be nice if Tesla initiated the same.

Did this cause the brake pads to wear faster?

 

[sakimano]

Did this cause the brake pads to wear faster?

Don't think so, it's not much pressure if at all.

 

[fasteddie7]

I agree with something on the brake components. Always happens to me after a touchless car wash. The first application of the brake is much more forceful than subsequent ones.

 

[Phillip L]

i called the Service Department and the person who answered told me to pump the brake pedal a few times before moving the car. Worked well after work today. Brakes were fine. She said something about the cold weather having an effect.

 

[MP3Mike]

Interesting. My understanding was that if you put regenerative braking setting to "low" instead of "full" (or whatever the setting is on the settings page) OR if you have creep mode set to on, that you did not get full regenerative braking by full release of the "throttle" pedal and needed to depress the brake pedal to get it. It was explained to me to being similar to what the regenerative braking modes were on a hybrid, but I honestly never looked closely, so I'm happy to be told I'm wrong and learn something new.

If you set the regen to low I don't think you ever get the "full" regen, even when using the brakes.

 

[evp]

For the last week when I first drive my Model S 85 D the break pedal barely slows the car down. But the second and subsequent times it works normally. The weather has been about minus 5 or 6 degrees centigrade. This morning I was coming up to a traffic light and it turned amber, hit the breaks and no response, so I accelerated through the amber light. Tried the breaks just afterwards, worked fine. What gives?

I had the same experience driving across the country a few weeks ago. In the morning, temperature -9F, first two brake applications required full force and throw to have any effect. After that I drove for a quarter mile with the brakes lightly depressed (and the car whining at me for "both pedals depressed"); thereafter no problems.

 

[Phillip L]

yup

driving on a highway in a snow storm on saturday, and when I exited my brakes were barely effective at all in stopping the car. A layer of moisture had built up and iced over. Giving the pedal a good push while at speed will clear that, which isn't ideal when you're trying to exit a highway. Fortunately regen braking took care of most of the slowing down.
.

I think you may be right about the moisture. In fact, the day before I drove down to Toronto to pick up my family at the airport and drove back part way through that freezing rain. The next morning was when it happened the worst.