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Emergency braking question

kirkbauer

Member
May 31, 2015
623
242
Atlanta, GA
So I think I had emergency braking kick in today. I was rubber necking and didn't notice traffic stopping in front of me. I hit the brakes hard and then heard a beeping. When the beeping happened I think the brake went in further than I could push it and the car stopped shockingly quick. Is this normal?

In other words can the vehicle brake harder on its own than I can?

I actually ended up stopping so quickly I had to accelerate a bit to avoid being rear ended. Very impressive for a 5000lb car.
 

Carspotter Daily

Tesla > ICE
Aug 12, 2015
84
21
Hamilton, Ontario, Canada
That's wierd... I had a collision earlier with the car in front of me and my car was a fair bit away from her. My ebs did kick in almost immediately-before i could press the brake pedal. Some people in the car ahead of the car infront of us decided they would stop in the middle of the highway. Before the lady in front of us could brake she had hit the kind polish people who had stopped for no apparent reason and our EBS had kicked in. We really felt the weight of the car as it made its best attempt to stop. Unfortuntely we couldn't stop in time and crashed into the lady in front of us. The EBS did as it is supposed to as far as i'm concerned, and i don't think the pedal went further than i could press + the car took a while to stop, as expected as it weighs that much more than a regular sedan.

That's my story

Thanks, Spencer
 

kirkbauer

Member
May 31, 2015
623
242
Atlanta, GA
I wonder if the vehicle, when doing emergency braking, could supplement the normal brakes with the parking brake and/or higher than usual regen, even if for just a brief moment?

On that note, what is it that limits the regen to only 60kW?
 

mikeash

Active Member
Oct 26, 2014
1,105
699
Fairfax, VA, USA
I wonder if the vehicle, when doing emergency braking, could supplement the normal brakes with the parking brake and/or higher than usual regen, even if for just a brief moment?

On that note, what is it that limits the regen to only 60kW?

The brakes are more than strong enough to cause the tires to break traction with the road. The challenge for stopping quickly isn't to apply more braking power, but it's to avoid applying too much braking power so you don't skid (which of course is what ABS handles for you).

Good question on the regen, I'd like to know too! We know the battery can take 120kW when at a sufficiently low SOC, so I wonder if it's just an artificial limit to maintain consistency across normal charge ranges.
 

green1

Active Member
Mar 25, 2014
4,548
1,123
Calgary, Alberta, Canada
Good question on the regen, I'd like to know too! We know the battery can take 120kW when at a sufficiently low SOC, so I wonder if it's just an artificial limit to maintain consistency across normal charge ranges.
Would you want your regen to work differently depending on state of charge? That sounds like a horrible driving experience, and one likely to lead to very unexpected results. based on supercharger taper logs posted to this forum, 60kW looks like a great compromise, and if anything is already a bit aggressive for a rate that can be used at virtually any SOC
 

kirkbauer

Member
May 31, 2015
623
242
Atlanta, GA
Would you want your regen to work differently depending on state of charge? That sounds like a horrible driving experience, and one likely to lead to very unexpected results. based on supercharger taper logs posted to this forum, 60kW looks like a great compromise, and if anything is already a bit aggressive for a rate that can be used at virtually any SOC

I was just thinking it could temporarily allow higher regen during very hard braking, if the battery can take it. This provides better stopping power and less brake wear, and gets a little juice back :)
 

green1

Active Member
Mar 25, 2014
4,548
1,123
Calgary, Alberta, Canada
I was just thinking it could temporarily allow higher regen during very hard braking, if the battery can take it. This provides better stopping power and less brake wear, and gets a little juice back :)
Emergency situations should be rare enough that we don't care if we get any electricity back, or about brake wear. The important part is stopping the vehicle as quickly and safely as possible. In that regard, tires are the weak link, not the brakes, no sense adding complication.
 

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